My first floor heat is busted, husband replaced the thermostat, didn't help, called the oil company, emergency tech said the Taco zone valve is probably the problem. Went to look up some more info cause I used to work in HVAC and wanted to remind myself how the guts worked, and got a great smile out of your accent & realizing from the 508 on your truck that you're just a few towns over. Thanks for brightening up my crap night!
Our 3/4 pipe burst in the last cold snap here in WI....we were gone and the zone valve malfunctioned....no biggie, I have skills. Ordered all new Taco valves, control unit and will replace the copper with PEX. The boiler is around 10 yrs old and is the Burnham 204HNSL-BEI2....love it. I want to thank you for your videos...wish I would have taken this route as a profession...or at 51 I still may. Thanks Steve..!!!
Steven..... I especially appreciated the seemingly incidental comment you made at 4:38 about "putting a jumper across T-T" and that's what gets the boiler running. That said tons to me (a layman) and put many HVAC aspects into perspective. .....and in general, Thanks for your videos !
Only DC has negative & a positive. 60 Hertz changes direction 120 times a mintue. Halve of the time an AC wire is positive then the other halve negative. Wired a lot of these in years ago for a great plumber who could never figure them out. Great vid.Worked at a large candy company and they only used Regular solenoids valves on 120# of water pressure causing water hammer. Tried to talk them into Taco slow opening & closing valves.
Buddy your video just saved our butts today. I'm not much of a zone vale guy. The guy I was working with said he was! Couldn't figure out why the boiler wouldn't fire, we found your video and it saved the day!!
Tazco Zone Valve: Boiler control: sends 110v to transformer which becomes 24v Top wire: 24v from t-stat Middle wire: Common from transformer Bottom wire: goes back to the boiler control After t-stat is turned on, 90sec delay before top and middle wire are energized with 24v. After being energized, middle wire opens switch to bottom wire and the bottom wire goes back to boiler control. After being energized, and you have 24v on top and middle wire. Remove bottom wire and check for continuity (ohms). If there is no continuity, it is bad, middle and bottom wire are not closing switch. If there is continuity, it is good. Great video!
I had the opposite problem - circ would run non-stop 24/7 with zone valve closed. Had a sticky switch inside the zone valve. Vid helped trouble shoot that - much appreciated! Big thanks from Worcester County. Just in time for heating season - 38° here yesterday morning!
I've been in my house about 16 years...built new in 2006. I've gone through about 5 of these zone valves. Troubleshot and Replaced myself thanks to videos like this. At about $90.00 a pop this really adds up. It is always at the most inconvenient time too!! Wish they would have put circulator pumps at the beginning like steve said. Thanks for the Videos!
If you find that the value gets stuck in the on position you can take the head off, clean the plunger in the head and regrease it with a high temperature grease. I do this as normal maintenance every couple of years.
Thanks Steve, I really appreciate good people like yourself who take the time to share the knowledge on stuff like that. Very succinct video. 8 minutes that could save hours of work and tons of money.
Great video Steven. Thanks for explaining in detail and taking the time on your day off to make the video on the operation/troubleshooting of a Taco zone valve!
I just got out of school for hvac I took the heating world part of the industry I've been watching your videos for some time would like to say your videos are very informational and especially on the taco zone valve I'm out of tiverton Ri, noticed your company is in Dartmouth thought that was funny small world...keep up the awesome videos man
Steven - Thank you so much for this video. I've been chasing down a heating issue all weekend and this video helped me every step of the way - testing zone valves, changing power head, etc. In the end it was a dead thermostat. Warm and toasty now!
Thanks for the video Steve. I had one fail last night and wanted to know how to test them in the future. It looks like there are micro switches in the valve that detect piston position to enable wire #3. In your video you mentioned you need to remove the wire on number three to test. You should also be able to use your multimeter in voltage measure mode to determine if the unit switched on #3. Since voltage is potential, a value of 0V between #1 and #3 indicates a short. A voltage of 24VAC in this case indicates an open. With this method, a value of 24VAC between #1 and #2 indicates good input power. A value of 0V measured between 1# and #3 after 90 seconds indicates good feedback from terminal #3. Thank you again for this video!
its called and end switch all i know is how i found best to test them ..i am no expert just a working guy and thats what i do as far as your way i don't know ... best to follow my directions and you will make it work ..
If I am reading 24V between both 1&2 and 1&3 (after 90s), yet the zone is still not warming (while the other two zones ARE working in a single circulator, 3-zone system), where to look next? The t-stat is set to 68, but room is still in 50s and no heat coming from baseboard. Also don't hear circulator or boiler kicking on. Despite the voltage check (above). If I switch the "bad" zone to open and raise temp on another zone I do get heat cycling through the "bad" zone baseboards, but of course means it's no longer being controlled by its dedicated thermostat.
Thanks for the review on these things...I have three of them, spent some time studying them a few years back, but forgot everything by now....I woke up to no hot water on my Weil Mclain system with the hot water heater that is powered by hot water pipes from the gas boiler. The only way I could get hot water was to turn on the heat on the second floor, then manually open the Taco valve to the hot water heater/tank while the boiler was running/recirculating...I came back to the basement a little while later only to find the taco valve seemed to be smoking a bit. Shut the power off to the boiler at the switch by the boiler, but was confused when there was still 24 volts at the taco valve....Figured that out, the transformer was wired before the emergency switch at the boiler, so had to throw the breaker for the boiler to kill the 24volts. Fortunately, I had a spare Taco valve on hand...Measured the resistance between the top two posts of the good valve, was about 20 ohms. Measured the resistance of the smokey valve, infinity. Replaced the valve and all seems to work OK now. Now I just have to figure out why the expensive Weil Mclain tank seems to be weeping underneath....Sure wish Steve worked in Providence....
Steve This video and your video on the no heat call were very useful and to me inspiring! I have been struggling with one zone causing what seemed like a short cycling of the furnace and was frustrated by it. I have a two zone system and swapped the identical thermostats to rule that out. I did the trouble shooting with the volt meter and saw that sometimes it just dropped the 24 volts to the circulator way before the thermostat was satisfied. also the lever was really stiff and rough to move after the call for heat. Bottom line - after watching your videos i stopped by Lowe's today and got a replacement power head and in 15 minutes I was up and running. Problem solved!! You get credit for a successful service call even if I didn't pay you!!
Thanks Steve, you were the only one that had positive and negative in your diagrams or load and common. The new thermostats require power and ground to power the Wi-Fi, now I know which is positive and negative, is also important so doesn't clash with the internal boiler transformer.
Buddy Smith if you tie the two transformers together if the wires spark when you touch them together ,,switch the wires so there is no spark .then your good to go ..a electrion showed me that years ago.
Just an fyi, the term positive and negative is used in DC circuits. This is an AC circuit. Both go positive for a half a cycle then negative the other half. I would use the reference to the circuit as hot and neutral just to avoid confusion but I get where you are coming from trying to make it understandable in layman's terms for people. Thanks for taking the time to make the informative video Steven!
Hi Steven, nice video. Thanks for share it. As far I know this valve works with AC volt. I would say "live wire" instead of "positive", and "neutral' instead of "negative". Thanks again.
Thank you from Nome, Alaska. If you ever want to explore Nome Alaska you would be an excellent teacher to put on a class up here to have an expense paid trip to Alaska to teach some boiler skills 101.
Just a little more info: These zone valves work the same way most auto engine thermostats work. There is a wax like material surrounding a valve stem inside a wax filled tube. When heated, this wax expands and causes the valve stem to get pushed out of the tube and pushes open the valve seat. Taco calls it a heat motor. The heat in this case is supplied by an electrical coil around the tube which heats the wax material in the tube when energized by the tstat. (in a car the engine makes the heat). What is really interesting in this design is the heater in the valve is continually cycling on and off via a switch that senses the position of the valve stem. When the valve is full open the heater switches off. Then as the wax cools slightly the valve stem returns back into the wax tube (the wax contracts when cooled) closing the valve. As the valve closes slightly the heater switch is made again and reheats the wax continuing the on of cycle of the heater. This prevents overheating of the wax and failure of the valve. This "mechanical" wax part of the valve is the only real moving part and my guess is it is the most likely cause of valve failure. In fact you noted in your video at one point on how hot some bad zone valves felt in some cases. This would be clear evidence that the heater switch was never cycling on and off because the heat motor failed (the wax part not the heater part) and no stem movement was occurring causing no cycling of the heater and hence overheating of the unit. Whew! a lot of words!!! the Taco website has a good picture of the valve and a better description in many ways. www.taco-hvac.com/uploads/FileLibrary/100-3.pdf Great videos!
Michael Licitra well i change out a lot of zone valve heads ,they burning all the time ,or die . most of the time they just shit the bed .and not smoke up ..but they do keep my busy .so maybe they need to come up with a better design .
No, the valve power heads are only hot in the case of these because they are sitting atop of a valve body and copper piping with 200 plus f water flowing through it. They don't get hot from the mechanics of them. They are only 24 v and give off very little heat. This would be evident when you have them installed on a cold start system , before the water gets hot, they are room temperature or just a few degrees warmer maybe. And on a boiler that's not firing do to any reason, still room temp even though it's powered open. You are correct about the wax heating up to move the plunger though to an extent, but not fully correct with everything
I've learned so much from your video, and I'll reference this when I add my second zone in my basement I'm finishing. Thank you for you video, well done.
Hi Steve, My Zone Valve Was RED HOT And I had no heat to the first floor. If I Threw The Lever Down Then, And Only Then, Would The Circulator Pump Operate. However It Would Never Stop Running. The Boiler Heat Would Cycle Off, Obviously On A Safety. But The Circulation Pump Wouldn't. I Found That Even Using It That Way, In Over-ride, My Heating Bill Was Significantly Less. I had a zone valve but I'm like the shoe maker with no shoes. I Finally got around to installing it today. Your Input on that scenario would be appreciated. Great Explanation by the way.
HVACENGINEER Moran change the head rtwist and pull up to remove the head,but never touch #1 and # 2 wires together it will buck the transformer,when you have the head off make sure the plunger pushes down with pump plyers easy.
Steven, Thank you for this great video. It helps me to replace the valve head many times at home. This winter, I saw that between terminals 1 and 2, there are 48 volts. Please explain where the extra voltage of 24 volts is coming from to terminal -1? I just turned the whole system off this winter.
Stephen, Nice Job! you should include that the 90 second delay is also a slow open and slow close function designed into the taco to eliminate the "slamming" of H2O in the pipes when the valve opens and shuts.
In your diagram the tt terminals are connected directly to the common side of the 24 transformer. Do the TT terminals have 24 Volts? If that’s the case, how does the tt terminal 24 v not damage the 24 transformer - that would leave a hot wire connected directly to the common side of the transformer. I’m a long time fan of yours Steve. ThAnks for all the great videos!! I’m learning so much from you. You are a gem! 👍😎
How is the thermostat wired in the back with the red wire? So once you wire Red into red on the thermostat, is the output on the red too or on the white before going to the power head?
great video. thank you very much! explained alot. for some reason when my thermostat calls for heat everything seems to work as you daid except when my boiler hits the high limit both boiler and circulator stop. the circulator only seems to run when the burner is running so the unit short cycles on and off bouncing off the high limit and almost no heat is seen at the baseboards. when i manually move the zone valve lever however the system seems to work properly but is no longer controlled by the thermostat. is it possible that the end switch is being activated to allow the burner to fire without actually opening the zone valve?
This was a very good video. I had already checked voltage and with one zone calling for heat, the voltage will toggle every five seconds or so between 24-27VAC. If I turn on a second zone, the voltage at each Taco head toggles between 22-24.3VAC. Is this a control board issue that would turn on the circ pump?
Great video. I just changed one of these heads out and it’s working but the old/ existing head had a little jumper between terminal 1 and 2. Any thoughts on that? It’s a single zone with two valves.
T T inside the controller are terminals from another transformer. In essence you have the load terminal on the controller transformer (one of the T's) connected to the common terminal of the stand alone transformer. Isn't this a problem?
What is the function of the lever that has two positions: open and closed. I've seen all the zone valves stay open 24/7, and I've also seen all zone valves stay closed 24/7. Both ways showing 24v. And when the lever shows they are closed, scalding hot water is still passing through the pipe all the time.
Steve it look like you have one leg comming off of the common to the tt but you also have the same leg comming from the transformer going to the tt that doesn't work. There must be one leg from the pos and one leg fro the neg to the tt. Unless #3 on zone valve is a pos. Is this right ?
Is the arm supposed to go to the open position when energized, or it happens internally, and you're only supposed to manually put the arm to open if the electronics stops working? Thanks
+Martin Odonell yes, in my buildings I'm able to run up to 12 zones on one calculator. you just have to make sure your calculator is big enough to pump all that water when needed.
Steve, You have two negatives going to TT on your hand drawn flow diagram which is wrong. The positive from step down transformer should go direct to TT. When end switch on taco power head makes the contact, the negative should now go to TT to energize every thing since positive is already there direct from transformer. Right?
Question: There are 8 zone valves for 8 apartments. The valve I was checking only had 2 wires attached (1 & 2, no 3rd) . Is this correct? I am not a heating guy and the wiring for these valves is a rat's nest to me. We do have a company plumber but I want to know more, for myself. Thanks.
Hey Steven, I just bought a house that's over a hundred years old. It still has the gas connections for lighting. So I'm trying to retro-fit all this new technology: Networking, new wiring, PEX plumbing, radiant floor-heating, etc. I liked your idea about using circulator pumps instead of Zone valves. Can you help me out, or make a video on how you would go about this?
good explanation, understand now what its doing...., 2&3 is just a DRY set of contacts. Terminal 1 is R, Terminal 2 is C, terminal 3 will be C but only after the wax heater in the power head closes the end switch, then both 2&3 are common C. I understand why you call the low side of voltage + and - for the general public although you and I now its actually AC voltage. We try not to do that and just call The R terminal the HOT side instead, and the common side C,( or the return side) so the T T terminals just continue the C connection to complete the circuit to pull in the plunger coil on the furnace control Now most of these have what we called a grounded C terminal, and the 40VA transformer can usually handle 3 Tacos zone valves, because they claim usually never will all 3 be calling at the same time, and for a short while it can handle 3. When you start mixing in these voltages of the separate transformer I guess its alright as long as the R side stays separate, now looking back at it......, the common on the transformer and the burner control ( T T ) ARE actually the same if they are both grounded..right??? .
I was a little confused by the drawing at first but I think I understand it now. One of the T terminals on the control is supposed to be from positive then goes through the board to the other T terminal then to #3 on the zone valve and once the end switch makes connects #2 and #3 completing the circuit to the negative side of transformer. Is this correct?
This video is exactly what I was looking for... Now to take it a step further. I've installed a nest thermostat and it calls for a common wire. You mention Common wire on Number 2 zone valve. I'm assuming that I can attach a wire to this and run it up to the new thermostat and connect to common. Are my assumptions correct? Fantastic video, great explanation. Thank you
New subscriber here! 👋 Thank you, Steven, for this very informative video! I’m having an issue with this particular zone valve and you’ve explained it perfectly!! I will, definitely, recommend your channel to others. Looking forward to watching more videos! Thanks again!! ~Nadine
Great video. Does anybody know how can you test , with multimeter ,used , taco 555 valve with only disconnected powerhead . Should all terminals have continuity? Or just 1 and 2 and 2 and 3 ? Thank you .
Hi Steve this is the 2nd time you have helped me out, 1st time was my A/C unit outside and now the trouble shooting of my Taco Zone head, I replaced it and it works great. quikc question, I'm trying to install a wifii thermostat. I have the blue wire but unit won't work. I jumped wires Red to Yellow = 27 volts, Red to Green = 27 volts, Red to White =27 volts, RED to BLUE = Freaking 48 Volts . I followed that blue wire to my air handle and it is on a transformer on the 24 volt side. I'm so confussed any thoughts thanks
Hi Steven, I'm hoping you can help me out. I am hooking up a new programmable thermostat that requires c wire. I currently have the old mercury thermostat (2 wire). My question is can I connect a wire from terminal number 2 on the taco zone valve which is connected to the transformer common wire and run it to the thermostat for the c wire? there is a extra wire run with the thermostat wires that is not being used. I am 99 percent sure this will work but wanted to ask the expert to verify this before I attempt the job. Thank You, Don
I’m having an issue with mine. I have 4 zone valves I thought I had a bad circulator so I installed 007e no light and it would not work. I installed a new aquastate Honeywell L8148A1017 It’s a replacement for my L8148A1090.. I have the circulator running now but it only works when the burner is on. I’m pretty sure it used to run until the heat was satisfied. Do you have any idea or what I should look for? Thanks
merry christmas steven i have a zone that doesnt stop putting out heat replace the thermostat and same thing thing i moved the manual lever it feel like it has no resistance like the other ones i think its a bad valve does this make sense to you? i have a v8043e1012 valve looks old
Best video!!! Love the simplicity of it. Keep them coming. Quick question, if I the boiler didn't turn on because the end switch inside was broken, I can jumper switch 2 & 3 from screw to screw and it should turn on right? end switch is nothing more then something like a light switch?
Nielubie correct but if you jump 1 and 2 on zone head when calling for heat you will fry the transformer so be carefull .i usally disconnect 3 and doa ohms test detween 2 and 3 with wire disconected .thats the best way.and when the zone calls it takes 90 seconds to enengize 1 and 1/2 minites
I Steve I have a boiler with 2 zones 2 thermostat s the second zone was added last year to a addition now when first zone comes on every thing runs smoothly 2 zone comes on the hot water is going back up the return s from the first zone any idea what its happening here????
I have 2 zones in my house, 1 zone is baseboard heat and works perfectly fine, the other zone is several radiators and im getting very very little out. The thermostat never kicks the boiler on either. Also, the Taco valve is super hot though, like i can only touch it for literally 1 second. Guys have told me to bleed all the radiators, but my gut is saying the valve is the problem. Ive never used a multimeter, but i do have one. Any suggestions.
I have two zones 1 for up stairs and one downstairs. Right now I have no hot going to the down stairs zone. The pipe is hot up until the Taco for that zone and feels cool behind the taco valve. If I manually push the valve lever to open should that turn on the zone?
Hey Steve, If you have 3 from the zone valve going to T on the aquastat and the other T from the aquastat going to the transformer, will that buck the transformer? Doesn't T&T on the aquastat get 24 volts from the transformer in the aquastat?
the t t on the aquastat is both the common side of the transformer .you can never sent 24 volts to something unless there is a load like a light ect.. the t t is just a switch.if you touch the t t together the relay will click in its just a switch .you can never buck a transformer or it will fry
Steve, what do you suppose it means when the thermostat is not calling for heat, but the circulator still runs. And no voltage on any of the 3 wires. A new system too, just started doing this. And it's also intermittent.
there is something turning the cerculator or you have to find out what is doing it i would start by pulling off t stats maybe a pinched /bad wire in the wall .its hard to say over a email with out looking at job
I just serviced one of these where the end switch for the wax motor heating coil failed, and this caused the wax to superheat, I stupidly pulled it off hot and got showered in boiling hot wax, had to go to the ER because it got in my eyes. Doing better now but it burned the shit out of me, turn off the power and wait for it to fully cool down before servicing.
Steven- Thank you very much for the video. So, i have noticed that one of the zone valve control is VERY HOT, the pipe kind of warm. meanwhile, that zone(area) temperture is not going up. does that mean the head unit is dead? what's the life span on these?
+Wayne Lee usally if there hot it might be bad .you have to test it . also the bottom part might be stuck you have to check that with pump plyers to see if it moves freely
The idea of zone valves over pumps is zone valves are more efficient than pumps. 1. Less parts, if you have a 3 zone pump system you are going to need, a 3 zone relay, 3 circulator pumps, and 3 flo-checks. Your relay on the boiler itself now becomes only a burner relay, and the circulator becomes useless. With zone valves you need only need to add 3 zone valves and a transformer. No flo-checks no pumps, no flanges, etc. 2. Less space. Zone valves aren't large and don't need alot of room to work on, circulator pumps you'll need the room for removal/replacement. 3. Emergency repair, if a zone valve or a thermostat is not work, zone valves can be opened manually to give temporary heat as long as another thermostat is calling for heat. If a circulator zoned system has a bad circulator your only choice is to open that flo-check and hope the others circulator pumps have enough force to pull the water through that bad zone. 4. Ease of replacement. Most of the time a zone valve goes bad due to a faulty motor, you can easily replace just the zone valve head, without dropping water out of the boiler. This can be done with circulator pumps as long as there are isolation valve for that particular pump which is more cost to install. Zone valves >>> circulator pump zones.
I’m having a problem with my zone 2 it’s not working I bought the taco valve I changed the thermostat to begin but the taco valve i can open and close easily I was told I could probably have air in my lines help please..
I have a two zone setup (similar to what you've described) and I want to replace an old thermostat in one zone with a Honeywell wifi programmable one. There are only two wires running to the old thermostat (like what you show in your diagram) but the new thermo requires a third wire running from the "C" terminal. Where would I find that "C" terminal ?
Patrick B c =common on transformer the red wire =r h is the hot feed from transformer feeding the t stat so you will have 24 volts to run the t stat .some of them you can use batteries ,to run depends on t stat
+Eric Tyler no voltage is needed o t. t .on control just touch then together and in energizes . voltage will cause a direct short . its just a end switch so the 2 common legs is what you need . or just a jumper would work also .hope this makes sense
There is definitely a problem with the wiring. When you have a TT , one T sends out a current, and the other T checks if it receives it. In this diagram, you have another current interfering - the one from the transformer. Might work, but sloppy and could be a short. Ideally a 4 terminal zone valve would be appropriate, where the end switch terminals are hooked up to the TT; i.e. Independent from the current of the transformer. Btw: Love your videos. Watch them everyday.
Art W That's a point. TT activates the burner and circulator when you are using the internal transformer for power and a T-stat as a switch: power out and returns hot to a built-in relay coil and then to common internally in the boiler control. The Heat motor returns to the same common. With an external xfmr you need an isolation relay to keep the external xfmr from bucking the internal one (unless you get the polarity right). Also, contacts 1 and 3 "make" via the end switch from what I've seen (power from 1 splits internally in the valve as some diagrams show) . Then you get a complete circuit (contact 3 continues as "hot" and goes thru isolation relay coil -the load- and again joins the return side of the heat motor and on to the external xfmr. The external relay contacts then can go to TT and activate the boiler control like a T-stat.
Art W 2nd try. I used a generic diagram on my first try. Main idea is to keep the strong external xfmr separate from the one in the boiler control (B.C.). Steve L. is a sharp guy but he should have had terminal 3 wire as "+" using the hot side of T-T off the B.C. , then neutral out term. 2 to neutral T. That way the end switch of the Zone valve takes the place of the T-stat, but sticks with the B.C. as the power source- which does its thing when switch closes, ie burner on, circulator on. The external xfmr power goes thru the thermostat but only operates the zone valves (hot in at terminal 1, thru zone valve heater and out at term. 2 (shared neutral), then back to external xfmr neutral). So power sources stay isolated.
Yo i just gotta know how to turn to turn this thing down manually cause i live in an apartment and they aren't fixing my thermostat and its 80 degrees in my apartment. Just please tell me how to turn it down.
Thank you Steve for explaining it all better! I followed your other video to troubleshoot the zone valve. I followed your suggestion & completed the job. Everything worked great for two days. This morning my wife messaged me at work to say we don’t have heat on our second floor. (Mind you this was the exact same issue three days ago). So, I’m lucky, I bought two brand new zone control valves after I bought my house 17 years ago. Is it possible to have two zone control valves fail? I’ll install the third tonight. I’m keeping my fingers crossed that this will be the fix?
My first floor heat is busted, husband replaced the thermostat, didn't help, called the oil company, emergency tech said the Taco zone valve is probably the problem. Went to look up some more info cause I used to work in HVAC and wanted to remind myself how the guts worked, and got a great smile out of your accent & realizing from the 508 on your truck that you're just a few towns over. Thanks for brightening up my crap night!
If you have basic HVAC knowledge, this video is great 👍. I diagnosed the issue and will now be ordering a new valve / coil. Good job bud
Our 3/4 pipe burst in the last cold snap here in WI....we were gone and the zone valve malfunctioned....no biggie, I have skills. Ordered all new Taco valves, control unit and will replace the copper with PEX. The boiler is around 10 yrs old and is the Burnham 204HNSL-BEI2....love it. I want to thank you for your videos...wish I would have taken this route as a profession...or at 51 I still may. Thanks Steve..!!!
thanks tony for watching
Video still helping me 9 years later
Steven..... I especially appreciated the seemingly incidental comment you made at 4:38 about "putting a jumper across T-T" and that's what gets the boiler running. That said tons to me (a layman) and put many HVAC aspects into perspective. .....and in general, Thanks for your videos !
Only DC has negative & a positive. 60 Hertz changes direction 120 times a mintue. Halve of the time an AC wire is positive then the other halve negative. Wired a lot of these in years ago for a great plumber who could never figure them out. Great vid.Worked at a large candy company and they only used Regular solenoids valves on 120# of water pressure causing water hammer. Tried to talk them into Taco slow opening & closing valves.
Buddy your video just saved our butts today. I'm not much of a zone vale guy. The guy I was working with said he was! Couldn't figure out why the boiler wouldn't fire, we found your video and it saved the day!!
flippowill thanks for watching
Ran into this today, Thanks for the info Steve!
This is the best educational video posted explaining this zone valve operation.
Terrific video better more concise and simpler than anything that the manufacturers put out
Tazco Zone Valve:
Boiler control: sends 110v to transformer which becomes 24v
Top wire: 24v from t-stat
Middle wire: Common from transformer
Bottom wire: goes back to the boiler control
After t-stat is turned on, 90sec delay before top and middle wire are energized with 24v.
After being energized, middle wire opens switch to bottom wire and the bottom wire goes back to boiler control.
After being energized, and you have 24v on top and middle wire. Remove bottom wire and check for continuity (ohms). If there is no continuity, it is bad, middle and bottom wire are not closing switch. If there is continuity, it is good.
Great video!
Thanks Steve we only had 4 hours to cover hydronic in school and your videos are teaching me more about Diagnostic! keep up the good work
+george harris thanks for the comment
ran into that exact problem at work few weeks ago...valve was super hot and reading 24 volts but burner would not fire....i remembered this video..
I had the opposite problem - circ would run non-stop 24/7 with zone valve closed. Had a sticky switch inside the zone valve. Vid helped trouble shoot that - much appreciated! Big thanks from Worcester County. Just in time for heating season - 38° here yesterday morning!
+SS Smithsonite thanks for the comment
I've been in my house about 16 years...built new in 2006. I've gone through about 5 of these zone valves. Troubleshot and Replaced myself thanks to videos like this. At about $90.00 a pop this really adds up. It is always at the most inconvenient time too!! Wish they would have put circulator pumps at the beginning like steve said. Thanks for the Videos!
If you find that the value gets stuck in the on position you can take the head off, clean the plunger in the head and regrease it with a high temperature grease. I do this as normal maintenance every couple of years.
Thanks Steve, I really appreciate good people like yourself who take the time to share the knowledge on stuff like that.
Very succinct video. 8 minutes that could save hours of work and tons of money.
Great video Steven. Thanks for explaining in detail and taking the time on your day off to make the video on the operation/troubleshooting of a Taco zone valve!
sure glad i could help
I just got out of school for hvac I took the heating world part of the industry I've been watching your videos for some time would like to say your videos are very informational and especially on the taco zone valve I'm out of tiverton Ri, noticed your company is in Dartmouth thought that was funny small world...keep up the awesome videos man
The Oil guy thanks for watching .
Steven - Thank you so much for this video. I've been chasing down a heating issue all weekend and this video helped me every step of the way - testing zone valves, changing power head, etc. In the end it was a dead thermostat. Warm and toasty now!
+kellybaa glad i could help
Great video and dialog Steven! I was looking for how the taco valve works and now I know.
Thanks for the video Steve. I had one fail last night and wanted to know how to test them in the future. It looks like there are micro switches in the valve that detect piston position to enable wire #3. In your video you mentioned you need to remove the wire on number three to test. You should also be able to use your multimeter in voltage measure mode to determine if the unit switched on #3. Since voltage is potential, a value of 0V between #1 and #3 indicates a short. A voltage of 24VAC in this case indicates an open. With this method, a value of 24VAC between #1 and #2 indicates good input power. A value of 0V measured between 1# and #3 after 90 seconds indicates good feedback from terminal #3. Thank you again for this video!
its called and end switch all i know is how i found best to test them ..i am no expert just a working guy and thats what i do as far as your way i don't know ... best to follow my directions and you will make it work ..
Thanks for the break down of voltage readings.
If I am reading 24V between both 1&2 and 1&3 (after 90s), yet the zone is still not warming (while the other two zones ARE working in a single circulator, 3-zone system), where to look next? The t-stat is set to 68, but room is still in 50s and no heat coming from baseboard. Also don't hear circulator or boiler kicking on.
Despite the voltage check (above). If I switch the "bad" zone to open and raise temp on another zone I do get heat cycling through the "bad" zone baseboards, but of course means it's no longer being controlled by its dedicated thermostat.
Thanks for the review on these things...I have three of them, spent some time studying them a few years back, but forgot everything by now....I woke up to no hot water on my Weil Mclain system with the hot water heater that is powered by hot water pipes from the gas boiler. The only way I could get hot water was to turn on the heat on the second floor, then manually open the Taco valve to the hot water heater/tank while the boiler was running/recirculating...I came back to the basement a little while later only to find the taco valve seemed to be smoking a bit. Shut the power off to the boiler at the switch by the boiler, but was confused when there was still 24 volts at the taco valve....Figured that out, the transformer was wired before the emergency switch at the boiler, so had to throw the breaker for the boiler to kill the 24volts. Fortunately, I had a spare Taco valve on hand...Measured the resistance between the top two posts of the good valve, was about 20 ohms. Measured the resistance of the smokey valve, infinity. Replaced the valve and all seems to work OK now. Now I just have to figure out why the expensive Weil Mclain tank seems to be weeping underneath....Sure wish Steve worked in Providence....
Steve This video and your video on the no heat call were very useful and to me inspiring! I have been struggling with one zone causing what seemed like a short cycling of the furnace and was frustrated by it. I have a two zone system and swapped the identical thermostats to rule that out. I did the trouble shooting with the volt meter and saw that sometimes it just dropped the 24 volts to the circulator way before the thermostat was satisfied. also the lever was really stiff and rough to move after the call for heat. Bottom line - after watching your videos i stopped by Lowe's today and got a replacement power head and in 15 minutes I was up and running. Problem solved!! You get credit for a successful service call even if I didn't pay you!!
SirLonneth bbh
5:55 You have 24 volts AC negative or white going to the Boiler Control twice. Once directly from the transformer and again from the zone valve.
Thanks Steve, you were the only one that had positive and negative in your diagrams or load and common. The new thermostats require power and ground to power the Wi-Fi, now I know which is positive and negative, is also important so doesn't clash with the internal boiler transformer.
Buddy Smith if you tie the two transformers together if the wires spark when you touch them together ,,switch the wires so there is no spark .then your good to go ..a electrion showed me that years ago.
Just an fyi, the term positive and negative is used in DC circuits. This is an AC circuit. Both go positive for a half a cycle then negative the other half. I would use the reference to the circuit as hot and neutral just to avoid confusion but I get where you are coming from trying to make it understandable in layman's terms for people. Thanks for taking the time to make the informative video Steven!
Hi Steven, nice video. Thanks for share it. As far I know this valve works with AC volt. I would say "live wire" instead of "positive", and "neutral' instead of "negative". Thanks again.
Angel Alburquerque lol don't be so technical .
Steve its you again, thanks for your time.
Thanks steve, your presentation was very helpful. As the back up maint its nice to have the "instructor" so close.
Thanks for this precious information Steve! Got 2 zones perfectly wired up after seeing this video 🙌🏻thanks a lot man!
I appreciate you going over this! Always wondered how they worked. You da man steve.
Thank you. Still helpful after 5 years.
Thanks for the video. Got a commercial Runtal system working using the wire diagram.
Thank you from Nome, Alaska. If you ever want to explore Nome Alaska you would be an excellent teacher to put on a class up here to have an expense paid trip to Alaska to teach some boiler skills 101.
I work on these a lot and I still learn a lot from you thanks
we all can learn from one another i always say .you should post some videos ace
Just a little more info: These zone valves work the same way most auto engine thermostats work. There is a wax like material surrounding a valve stem inside a wax filled tube. When heated, this wax expands and causes the valve stem to get pushed out of the tube and pushes open the valve seat. Taco calls it a heat motor. The heat in this case is supplied by an electrical coil around the tube which heats the wax material in the tube when energized by the tstat. (in a car the engine makes the heat). What is really interesting in this design is the heater in the valve is continually cycling on and off via a switch that senses the position of the valve stem. When the valve is full open the heater switches off. Then as the wax cools slightly the valve stem returns back into the wax tube (the wax contracts when cooled) closing the valve. As the valve closes slightly the heater switch is made again and reheats the wax continuing the on of cycle of the heater. This prevents overheating of the wax and failure of the valve. This "mechanical" wax part of the valve is the only real moving part and my guess is it is the most likely cause of valve failure. In fact you noted in your video at one point on how hot some bad zone valves felt in some cases. This would be clear evidence that the heater switch was never cycling on and off because the heat motor failed (the wax part not the heater part) and no stem movement was occurring causing no cycling of the heater and hence overheating of the unit. Whew! a lot of words!!! the Taco website has a good picture of the valve and a better description in many ways. www.taco-hvac.com/uploads/FileLibrary/100-3.pdf Great videos!
Michael Licitra well i change out a lot of zone valve heads ,they burning all the time ,or die . most of the time they just shit the bed .and not smoke up ..but they do keep my busy .so maybe they need to come up with a better design .
No, the valve power heads are only hot in the case of these because they are sitting atop of a valve body and copper piping with 200 plus f water flowing through it. They don't get hot from the mechanics of them. They are only 24 v and give off very little heat. This would be evident when you have them installed on a cold start system , before the water gets hot, they are room temperature or just a few degrees warmer maybe. And on a boiler that's not firing do to any reason, still room temp even though it's powered open. You are correct about the wax heating up to move the plunger though to an extent, but not fully correct with everything
@@HVACRTECH-83 Nope.
I've learned so much from your video, and I'll reference this when I add my second zone in my basement I'm finishing. Thank you for you video, well done.
Hi Steve, My Zone Valve Was RED HOT And I had no heat to the first floor. If I Threw The Lever Down Then, And Only Then, Would The Circulator Pump Operate. However It Would Never Stop Running. The Boiler Heat Would Cycle Off, Obviously On A Safety. But The Circulation Pump Wouldn't. I Found That Even Using It That Way, In Over-ride, My Heating Bill Was Significantly Less. I had a zone valve but I'm like the shoe maker with no shoes. I Finally got around to installing it today. Your Input on that scenario would be appreciated. Great Explanation by the way.
HVACENGINEER Moran change the head rtwist and pull up to remove the head,but never touch #1 and # 2 wires together it will buck the transformer,when you have the head off make sure the plunger pushes down with pump plyers easy.
Steven,
Thank you for this great video. It helps me to replace the valve head many times at home. This winter, I saw that between terminals 1 and 2, there are 48 volts. Please explain where the extra voltage of 24 volts is coming from to terminal -1? I just turned the whole system off this winter.
Steve, thank you very much for posting this video, it helped me comprehend how this component works!
Stephen,
Nice Job! you should include that the 90 second delay is also a slow open and slow close function designed into the taco to eliminate the "slamming" of H2O in the pipes when the valve opens and shuts.
good point,, thanks for commenting
In your diagram the tt terminals are connected directly to the common side of the 24 transformer. Do the TT terminals have 24 Volts?
If that’s the case, how does the tt terminal 24 v not damage the 24 transformer - that would leave a hot wire connected directly to the common side of the transformer. I’m a long time fan of yours Steve. ThAnks for all the great videos!! I’m learning so much from you. You are a gem! 👍😎
Excellent job. Appreciate you taking the time to do a great job.
raymond sherman thanks for the comment
Thanks Steve, great, simplified tutorial
How is the thermostat wired in the back with the red wire? So once you wire Red into red on the thermostat, is the output on the red too or on the white before going to the power head?
great video. thank you very much! explained alot. for some reason when my thermostat calls for heat everything seems to work as you daid except when my boiler hits the high limit both boiler and circulator stop. the circulator only seems to run when the burner is running so the unit short cycles on and off bouncing off the high limit and almost no heat is seen at the baseboards. when i manually move the zone valve lever however the system seems to work properly but is no longer controlled by the thermostat. is it possible that the end switch is being activated to allow the burner to fire without actually opening the zone valve?
This was a very good video. I had already checked voltage and with one zone calling for heat, the voltage will toggle every five seconds or so between 24-27VAC. If I turn on a second zone, the voltage at each Taco head toggles between 22-24.3VAC.
Is this a control board issue that would turn on the circ pump?
Great video. I just changed one of these heads out and it’s working but the old/ existing head had a little jumper between terminal 1 and 2. Any thoughts on that? It’s a single zone with two valves.
Great job on this video, the continuity comment help me diagnose my issue.
thanks for watching & commenting
T T inside the controller are terminals from another transformer. In essence you have the load terminal on the controller transformer (one of the T's) connected to the common terminal of the stand alone transformer. Isn't this a problem?
Can you do a video on a White Rogers zone valve it seems that the WR has alot of terminals on it?
is there a bench test for the opening and closing of the valve it self?
What's a better unit this or the taco with the ball valve?
What is the function of the lever that has two positions: open and closed. I've seen all the zone valves stay open 24/7, and I've also seen all zone valves stay closed 24/7. Both ways showing 24v. And when the lever shows they are closed, scalding hot water is still passing through the pipe all the time.
Steve it look like you have one leg comming off of the common to the tt but you also have the same leg comming from the transformer going to the tt that doesn't work. There must be one leg from the pos and one leg fro the neg to the tt. Unless #3 on zone valve is a pos. Is this right ?
where does the other thermostat wire go? does it connect to terminal two on the valve?
Steve, your vids are a great help.
Is the arm supposed to go to the open position when energized, or it happens internally, and you're only supposed to manually put the arm to open if the electronics stops working? Thanks
I learn a lot with this video.
3 taco zona can work with one circulator ? thanks
+Martin Odonell yes, in my buildings I'm able to run up to 12 zones on one calculator. you just have to make sure your calculator is big enough to pump all that water when needed.
Steve, You have two negatives going to TT on your hand drawn flow diagram which is wrong. The positive from step down transformer should go direct to TT. When end switch on taco power head makes the contact, the negative should now go to TT to energize every thing since positive is already there direct from transformer. Right?
Thank you. This was perfectly explained.
hey steve if i have one zone not working and the other 2 valves are warm to the touch and one is cold is that likely the head?
Question: There are 8 zone valves for 8 apartments. The valve I was checking only had 2 wires attached (1 & 2, no 3rd) . Is this correct? I am not a heating guy and the wiring for these valves is a rat's nest to me. We do have a company plumber but I want to know more, for myself. Thanks.
Great video, very helpful thank you! Why do you think I would have 25 volts with boiler and all t stats off as well? Happy Thanksgiving from NH! 🦃
When you check 2 and 3 for continuity you have to check it when the system is off right?
So the common wire carries current and closes a switch?
Great short little video. Very helpful.
Hey Steven, I just bought a house that's over a hundred years old. It still has the gas connections for lighting. So I'm trying to retro-fit all this new technology: Networking, new wiring, PEX plumbing, radiant floor-heating, etc. I liked your idea about using circulator pumps instead of Zone valves. Can you help me out, or make a video on how you would go about this?
good explanation, understand now what its doing...., 2&3 is just a DRY set of contacts. Terminal 1 is R, Terminal 2 is C, terminal 3 will be C but only after the wax heater in the power head closes the end switch, then both 2&3 are common C.
I understand why you call the low side of voltage + and - for the general public although you and I now its actually AC voltage. We try not to do that and just call The R terminal the HOT side instead, and the common side C,( or the return side)
so the T T terminals just continue the C connection to complete the circuit to pull in the plunger coil on the furnace control
Now most of these have what we called a grounded C terminal, and the 40VA transformer can usually handle 3 Tacos zone valves, because they claim usually never will all 3 be calling at the same time, and for a short while it can handle 3. When you start mixing in these voltages of the separate transformer I guess its alright as long as the R side stays separate, now looking back at it......, the common on the transformer and the burner control ( T T ) ARE actually the same if they are both grounded..right???
.
can actually visualize this now much better, Thanks again..
Very helpful, thank you for taking the time to post this video.
Thank you for the video you make it easy to understand how this zone valve operates and the system as a whole.
I was a little confused by the drawing at first but I think I understand it now. One of the T terminals on the control is supposed to be from positive then goes through the board to the other T terminal then to #3 on the zone valve and once the end switch makes connects #2 and #3 completing the circuit to the negative side of transformer. Is this correct?
+jourmomma yes 2 negitives will go to t t on control
I’m confused ! Wait 24vac has positive and negative?
This video is exactly what I was looking for... Now to take it a step further. I've installed a nest thermostat and it calls for a common wire. You mention Common wire on Number 2 zone valve. I'm assuming that I can attach a wire to this and run it up to the new thermostat and connect to common. Are my assumptions correct? Fantastic video, great explanation. Thank you
New subscriber here! 👋
Thank you, Steven, for this very informative video! I’m having an issue with this particular zone valve and you’ve explained it perfectly!! I will, definitely, recommend your channel to others. Looking forward to watching more videos! Thanks again!! ~Nadine
Great video. Does anybody know how can you test , with multimeter ,used , taco 555 valve with only disconnected powerhead . Should all terminals have continuity? Or just 1 and 2 and 2 and 3 ? Thank you .
Hi Steve this is the 2nd time you have helped me out, 1st time was my A/C unit outside and now the trouble shooting of my Taco Zone head, I replaced it and it works great. quikc question, I'm trying to install a wifii thermostat. I have the blue wire but unit won't work. I jumped wires Red to Yellow = 27 volts, Red to Green = 27 volts, Red to White =27 volts, RED to BLUE = Freaking 48 Volts . I followed that blue wire to my air handle and it is on a transformer on the 24 volt side. I'm so confussed any thoughts thanks
Hi Steven, I'm hoping you can help me out. I am hooking up a new programmable thermostat that requires c wire. I currently have the old mercury thermostat (2 wire). My question is can I connect a wire from terminal number 2 on the taco zone valve which is connected to the transformer common wire and run it to the thermostat for the c wire? there is a extra wire run with the thermostat wires that is not being used. I am 99 percent sure this will work but wanted to ask the expert to verify this before I attempt the job. Thank You, Don
+Don Pomroy yes #2 terminal should be a constant neutral
I’m having an issue with mine. I have 4 zone valves I thought I had a bad circulator so I installed 007e no light and it would not work. I installed a new aquastate Honeywell L8148A1017 It’s a replacement for my L8148A1090.. I have the circulator running now but it only works when the burner is on. I’m pretty sure it used to run until the heat was satisfied. Do you have any idea or what I should look for? Thanks
What if I get no voltage to the 5 zone valves. I had to manually open the valves to get the house warm lastnight.
merry christmas steven i have a zone that doesnt stop putting out heat replace the thermostat and same thing thing i moved the manual lever it feel like it has no resistance like the other ones i think its a bad valve does this make sense to you? i have a v8043e1012 valve looks old
Best video!!! Love the simplicity of it. Keep them coming. Quick question, if I the boiler didn't turn on because the end switch inside was broken, I can jumper switch 2 & 3 from screw to screw and it should turn on right? end switch is nothing more then something like a light switch?
Nielubie correct but if you jump 1 and 2 on zone head when calling for heat you will fry the transformer so be carefull .i usally disconnect 3 and doa ohms test detween 2 and 3 with wire disconected .thats the best way.and when the zone calls it takes 90 seconds to enengize 1 and 1/2 minites
I Steve I have a boiler with 2 zones 2 thermostat s the second zone was added last year to a addition now when first zone comes on every thing runs smoothly 2 zone comes on the hot water is going back up the return s from the first zone any idea what its happening here????
I have 2 zones in my house, 1 zone is baseboard heat and works perfectly fine, the other zone is several radiators and im getting very very little out. The thermostat never kicks the boiler on either. Also, the Taco valve is super hot though, like i can only touch it for literally 1 second. Guys have told me to bleed all the radiators, but my gut is saying the valve is the problem. Ive never used a multimeter, but i do have one. Any suggestions.
Steven is it true the make zone valves for a steam system?
I have two zones 1 for up stairs and one downstairs. Right now I have no hot going to the down stairs zone. The pipe is hot up until the Taco for that zone and feels cool behind the taco valve. If I manually push the valve lever to open should that turn on the zone?
Hey Steve,
If you have 3 from the zone valve going to T on the aquastat and the other T from the aquastat going to the transformer, will that buck the transformer? Doesn't T&T on the aquastat get 24 volts from the transformer in the aquastat?
the t t on the aquastat is both the common side of the transformer .you can never sent 24 volts to something unless there is a load like a light ect.. the t t is just a switch.if you touch the t t together the relay will click in its just a switch .you can never buck a transformer or it will fry
steven lavimoniere
Thanks!
Steve, what do you suppose it means when the thermostat is not calling for heat, but the circulator still runs. And no voltage on any of the 3 wires. A new system too, just started doing this. And it's also intermittent.
there is something turning the cerculator or you have to find out what is doing it i would start by pulling off t stats maybe a pinched /bad wire in the wall .its hard to say over a email with out looking at job
Great description Steve
I just serviced one of these where the end switch for the wax motor heating coil failed, and this caused the wax to superheat, I stupidly pulled it off hot and got showered in boiling hot wax, had to go to the ER because it got in my eyes. Doing better now but it burned the shit out of me, turn off the power and wait for it to fully cool down before servicing.
Steven- Thank you very much for the video. So, i have noticed that one of the zone valve control is VERY HOT, the pipe kind of warm. meanwhile, that zone(area) temperture is not going up. does that mean the head unit is dead? what's the life span on these?
+Wayne Lee usally if there hot it might be bad .you have to test it . also the bottom part might be stuck you have to check that with pump plyers to see if it moves freely
To do this you just remove the head and try opening the valve with the plyers?
The idea of zone valves over pumps is zone valves are more efficient than pumps.
1. Less parts, if you have a 3 zone pump system you are going to need, a 3 zone relay, 3 circulator pumps, and 3 flo-checks. Your relay on the boiler itself now becomes only a burner relay, and the circulator becomes useless. With zone valves you need only need to add 3 zone valves and a transformer. No flo-checks no pumps, no flanges, etc.
2. Less space. Zone valves aren't large and don't need alot of room to work on, circulator pumps you'll need the room for removal/replacement.
3. Emergency repair, if a zone valve or a thermostat is not work, zone valves can be opened manually to give temporary heat as long as another thermostat is calling for heat. If a circulator zoned system has a bad circulator your only choice is to open that flo-check and hope the others circulator pumps have enough force to pull the water through that bad zone.
4. Ease of replacement. Most of the time a zone valve goes bad due to a faulty motor, you can easily replace just the zone valve head, without dropping water out of the boiler. This can be done with circulator pumps as long as there are isolation valve for that particular pump which is more cost to install.
Zone valves >>> circulator pump zones.
excellent video.i learnt the hard way.keep it up.
+Devinder Chana thanks for the comment
I’m having a problem with my zone 2 it’s not working I bought the taco valve I changed the thermostat to begin but the taco valve i can open and close easily I was told I could probably have air in my lines help please..
Sorry for delay. Thanks Steve, I Swapped it out. All Good!!
I have a two zone setup (similar to what you've described) and I want to replace an old thermostat in one zone with a Honeywell wifi programmable one. There are only two wires running to the old thermostat (like what you show in your diagram) but the new thermo requires a third wire running from the "C" terminal. Where would I find that "C" terminal ?
Patrick B c =common on transformer the red wire =r h is the hot feed from transformer feeding the t stat so you will have 24 volts to run the t stat .some of them you can use batteries ,to run depends on t stat
How does the system energize if both 'T's' on the boiler are common?
+Eric Tyler no voltage is needed o t. t .on control just touch then together and in energizes . voltage will cause a direct short . its just a end switch so the 2 common legs is what you need . or just a jumper would work also .hope this makes sense
+steven lavimoniere it is just a contact which is jumped by the end switch.
There is definitely a problem with the wiring. When you have a TT , one T sends out a current, and the other T checks if it receives it. In this diagram, you have another current interfering - the one from the transformer. Might work, but sloppy and could be a short.
Ideally a 4 terminal zone valve would be appropriate, where the end switch terminals are hooked up to the TT; i.e. Independent from the current of the transformer.
Btw: Love your videos. Watch them everyday.
Art W That's a point. TT activates the burner and circulator when you are using the internal transformer for power and a T-stat as a switch: power out and returns hot to a built-in relay coil and then to common internally in the boiler control. The Heat motor returns to the same common.
With an external xfmr you need an isolation relay to keep the external xfmr from bucking the internal one (unless you get the polarity right). Also, contacts 1 and 3 "make" via the end switch from what I've seen (power from 1 splits internally in the valve as some diagrams show) . Then you get a complete circuit (contact 3 continues as "hot" and goes thru isolation relay coil -the load- and again joins the return side of the heat motor and on to the external xfmr. The external relay contacts then can go to TT and activate the boiler control like a T-stat.
Art W 2nd try. I used a generic diagram on my first try. Main idea is to keep the strong external xfmr separate from the one in the boiler control (B.C.). Steve L. is a sharp guy but he should have had terminal 3 wire as "+" using the hot side of T-T off the B.C. , then neutral out term. 2 to neutral T. That way the end switch of the Zone valve takes the place of the T-stat, but sticks with the B.C. as the power source- which does its thing when switch closes, ie burner on, circulator on.
The external xfmr power goes thru the thermostat but only operates the zone valves (hot in at terminal 1, thru zone valve heater and out at term. 2 (shared neutral), then back to external xfmr neutral). So power sources stay isolated.
Where is the thermostat in your drawing?
Yo i just gotta know how to turn to turn this thing down manually cause i live in an apartment and they aren't fixing my thermostat and its 80 degrees in my apartment. Just please tell me how to turn it down.
Great explanation Steve thanks!
Thank you Steve for explaining it all better!
I followed your other video to troubleshoot the zone valve. I followed your suggestion & completed the job. Everything worked great for two days. This morning my wife messaged me at work to say we don’t have heat on our second floor. (Mind you this was the exact same issue three days ago). So, I’m lucky, I bought two brand new zone control valves after I bought my house 17 years ago. Is it possible to have two zone control valves fail? I’ll install the third tonight. I’m keeping my fingers crossed that this will be the fix?