HVAC Low voltage control wiring (Basics For Beginners)
ฝัง
- เผยแพร่เมื่อ 15 มิ.ย. 2024
- Follow the basic flow path of HVAC low voltage control wiring from the unit to the thermostat to the end results to see how it all works. Detailed drawing (Jpeg) here in description:
Image: ibb.co/9gL4X5V
#hvac
#hvactraining
#HVACwiring
I’m a new HVAC installer and have only been employed by a company despite not having any sort of schooling or knowledge about anything, After a month of practice I am able to do everything i need to help out my leads, but have been struggling to understand what each low voltage wire does and I feel significantly more comfortable with it after this video. It was very clear and helpful. Thanks man
This was THE best video on the topic. I have watched a lot that cover thermostat but I wanted to full picture which included the furnace controller card. This video was the best as I am an electrical engineer (not an HVAC expert or even an electrician) but I was going nuts not understanding how the 24 VAC closed the circuit. Nobody else explained it but this guy did! Now I feel confident rewiring my 50 year old house with labeled wiring for a tech or the next home owner. Thank you!
Nice. Glad it helped!
Your explanation was very clear. I worked part time with an electrician for six years. When I look inside my air handler it looks like a big jumble of wires. You made it very easy to understand. It’s just a bunch of different circuits. Great job! Best yet!
Mike, You are an excellent teacher. I am an electrical engineer but you made it a piece of cake to understand everything that is there to be learned about HVAC wiring in under 12 mins without any fluff or BS. I am surprised you just have 2.42K subscribers. More people can benefit from your top notch content. Thanks a bunch for putting this out
Thanks for the feedback. Really appreciate it!
Ditto!! Don’t need colors just the schematic and mike nails it!!
Jersey Mike , thankx. This was a perfect lesson that you made so easy to understand. You deserve a big thumb 👍 brother.
Hey man thanks for the upload I'm in my G2 class right now and I'm really struggling with the schematic and ladder diagrams. Thanks a bunch
This is by far the best overview of the low voltage wiring . By far! Thanks a bunch
Vrey good good bacl all
Just new coming in this world of HVAC. I can already tell the information on this video is going to keep me a step ahead of peers! Gem indeed!
Vrey good bacical
Great explanation, Mike!
Currently troubleshooting an issue. This is gonna make my life a lot easier.
Thank you kindly, sir.
Anytime. Thanks.
You made this simple and easy to understand! I have units with blue wire running to yellow and float switch wiring wired to the condenser instead of the 24v red etc….this cleared it all up and made my day! thank you sir!
One awesome explanation on "HVAC theory and operation" for us "newbies or DIYers" like nothing I've ever seen before on TH-cam......many thanks to "Jersey Mike's channel" here in providing real world experience and knowledge to this trade here.....much appreciated!!!!!!
Thank you, brother.
@@JerseyMikeHVAC Your very welcome!
Thanks so much, nice schematic drawing and very educational.
I've watched hundreds of videos this one by far is so far above and better than any of them it's unreal thank you so much I wish I would have found this video first thanks again
Thanks for the feedback, brother!
Really appreciate the videos and this one in particular! Really helps newer guys like me with a really straight forward explanation.
No problem.
Thanks man, a control wire had popped off my circuit board for the outdoor condenser and your video helped me to quickly put it back where it belonged on the common terminal. Also de-mystified the color code confusion overall👍👍
Thanks I just graduated from tech school and will be starting a new job I've been struggling with the low voltage part but this helped
This is good 👍 I got 5 years on really experienced with gas furnaces ( wiring is easy ) started with a new company that does a lot of air handlers an some times wiring is crazy specially when the last person splices a lot of different wires together
Super Basic but VERY Informative. Thanks much for the upload
Plain and straight forward explanation. Well demonstrated and detailed
Thank you
Thank you so much. I appreciate this content a lot.
your good! Real good teacher. thank you
I’m getting ready to start school for hvac. This was really helpful. Thank you !! I’m ready to start. Super nervous but ready to get my career going !
Glad it helps! Good luck!
Excellent video saved my ex gf $900 service call by reinforcing a reassuring my logic. Thanks!
Great explanation thank you Mike.
You are a great teacher. Respect for you my man
I appreciate that!
Thank you for the knowledge brother much appreciated
Best simplified explanation! Thank you for taking the time to make this video. Keep up the good work, and keep the videos coming! I would greatly appreciate it if you could make a video on how to hand fabricate a seamless drain pan, and how to wire a condensate pump into the alarm system so the float switch shuts down the unit if the drain pan gets wet.
I need a little clarity. Are you asking how to wire both a safety switch in a condensate pump and a float switch in a drain pan together into the control wiring to shut down cooling if either one is activated?
@@JerseyMikeHVAC safety switch in a condensate pump.
It would be the same as wiring a float switch as I described in the video.
One end wired to R terminal at the control board, other end running up to R terminal at tstat (to shut down everything). Or you can use Y terminals at the board and tstat instead (to shut down just cooling) If it's a 90% furnace that generates water you can even do the same with the W terminals (to shut down heating). Few different ways to do it.
@@JerseyMikeHVAC Thank you. I appreciate that you took the time to answer my question. Keep up the good work.
Great low voltage video , good job!
Plainly put. Good job!
Mike, I want to thank you very much I graduated from HVAC School back in 2020 and then pandemic first started so I never really got any on hands experience especially with the wiring however, thanks to your explanation of basic wiring. You opened up a whole new door for me. Thank you Marc Seraphin oh, Seraphins emergency air
You're welcome brother
Hey mate..for more learning..look up taddy HVAC . He has great video and is a great tech teacher..I'm a HVAC grad.and same story with me.i grad in 2019 and pan hot..so I been learning..he also has a subscription channel for more learning..best twenty bucks you will ever spend..I promise
Sir you’ve given me the perfect knowledge for the lab exam I have tomorrow on this topic. I’m going to do so well thanks to you 🙏
Most welcome. Did you pass?
@@JerseyMikeHVAC I did! Thanks again!
Very good explanation. Best I have heard so for
Brother, your diagrams look so good!
Thank you!
Print this chart and check both ends before you DIY to be sure the installation tech wired it this way, some use their own wiring preference to prevent home owners from working on it. Causes more damage THEY will benefit from in the end and being they are legal HVAC certified and homeowners are not a court will side with the tech. Like the video great wiring diagram layout to help.
Thanks for the big help 🙏
Finally. It finally makes sense. THANK YOU.
Youre welcome
Thank you so much for the amazing explanation!!!
You're welcome
Really helpful. Thank you👍
great explanation, thank you
Nicely though out tutorial..thanks mate
Informative, thank you.
Appreciate this, thank you
Jersey Mike's do you deliver......I had to....😮.... Great video Sir.... Thanks 🙏👍
Great explanation.
This video is amazing!!!!😊
awesome, thank you!
Thanks for sharing this videos really appreciate 💪🙏♥️🙏🙏
No problem 👍
Great video!!!
Great explanation ! 👍🏼
Thank you! 👍
Excellent explanation! Subscribed your channel
Thank you!
Great video
Gracias por compartir, I appreciate it
super helpful thank you.
You're welcome
Nice description man.
Thank you
Great education video! Liked and subbed!
Big thanks
Thank you sir You explained very nicely
You are welcome
awesome brother ty
Vry nicely thankyou my brethers
woke up to find out my heat never turned on, after watching some vids i found the low boltage fuse popped, replaced and still pops only on heat, trying to find out where the short is, this video is definitely the easiest to understand, within seconds of looking at the picture i was figuring out how it works. Thank You. hope i can fix my problem with the new knowledge.
No problem. Let me know if you find it.
@@JerseyMikeHVAC after 3 days of trying to figure it out i cant. no wires are exposed everything looks good. just blows fuse on heat, have been using ac fine. im trying to figure this out cause its for my mother and she cant afford to have a tech come out and look at it. ive learned a ton so far but cant fiigure it out.
@@wrench If it's just on the call for heat, it most likely has something to do with the wire between the W terminal on the thermostat and the W terminal inside of the furnace.
Do you have any extra wires available on that thermostat wire bundle? Maybe a blue wire unused? If so, disconnect the wire from both W terminals at the furnace and thermostat and reconnect the new wire to the W terminals at the stat and the furnace. See if that resolves the issue.
Great video! I'm going up on my prices!!!!
Excellant video!
Thanks!
I'm going to draw this out several times until I can do it by thinking it through
Great video man
Appreciate it
Best case of a so called union trained HVAC guy they called the filter king because it was the only job he couldn't screw up. He installed a maybe 5 ton AC unit in an office. He was so proud if himself he had the office manager watch him turn the unit in for the first time. Some how the filter king had the red wire going to the T stat connected to a 480 volt leg. Left a 4' high burn mark.on the wall.
"Some how the filter king had the red wire going to the T stat connected to a 480 volt leg"
Lol. I have SO many questions right now. I get on my guys for not doing a drain assembly just right. How is this guy not tied down to something right now?
@9:19 YOU CAN PLAY WITH THIS THING HOWEVER YOU WANT TO!
Very nice! 😊
Thank you! Cheers!
Whenever I get a new guy I like to sit down with him and ask him to draw me a ladder diagram including all voltages and terminal designations and ask him to explain the sequence of operation for a piece of equipment we are working on, it weeds out the guys who can walk the walk.
Would you be willing to teach them?
Good moring evrey bedy welcomed
I got light bulbs going off in my head right now
An Former Jersey man here. What a great video! Could you please help me out. I just installed a MrCool 36K hyper heat system. It is working fine, with the thermostat that came with the unit, (its only a 2 wire setup). Question is I would like to use my nest thermostat with the new unit. Would you please tell me how to connect the wires up. I don’t want to screw this up, by guessing it. Thank you so much, if you can help me.
thanks! new too hvac. install / changeout helper. this is gonna help me so much. smoke detector work the same as a float switch? how would u wire in a smoke detector in as well as a float switch. I can get the answers from work but the more I learn on my own the better I look (yes I should probably know this)
It would be better to learn that at work. Most companies stick with one or two particular brands and styles of accessories, where as there can be dozens of different types out on the market that may be wired differently from one another. Two different guys can also wire the same thing in different ways.
All accessory items come with instructions and wiring diagrams. A good way to learn is to grab these manuals after an install is done and keep them to read and for reference.
You don't have to memorize it all just figure out one wire at a time, what it does, where it goes, etc The next time that accessory item is being wired in, try to pick out that one wire. Once comfortable with that, move on to learn another wire, and so on.
Thanks man
Concise!
Hey Mike, love your videos. Got a question for you.
Have you ever used a decade resistance box to bypass a temp sensor temporarily?
If so, how would you wire that in as most temp sensors just go to a board or t stat
Can't say I ever have. In most cases I have just disconnected the wires from the stat or board. Had a combi boiler recently (Triangle Tube I believe), where I just changed the programming to deactivate the remote sensor, so didn't even have to disconnect the wires.
Don't believe temp sensors offer up much resistance anyway. Don't want to say with certainty, but alligator clips might even work.
@@JerseyMikeHVAC thanks mike!
Thanks 👍
Welcome 👍
Great Videos. I got into installing a NEST ans it was not as simple as they say. Gland I found your videos. BUT I dont have the answer. The Nest was installed as best I could it run a test and worked well on cool Then, after . UNTIL i installed the goggle app the display showed Cool but air was blowing hot? I reverted to the old thermostat all is working as it did before.
Sounds if breaking Y(yellow) wire would be good method with float switch?
Is this way u would wire?
Great explanation with video.
Breaking Y is perfectly acceptable, but I have a tendency to break R instead. The reason why is because on a straight cool system, all that breaking Y really does is shut down the outdoor unit. Blower will still run inside. And in many cases, customers don't realize their AC is not working when they can still hear it running. It takes hours for them to realize it. Then they're calling you at 5 pm and want you to come immediately. Breaking R shuts it all down and customers will catch it sooner.
Another reason I go with R is because sometimes I have other parts of the system generating water even when cooling mode is not activated, like a 90% condensing furnace, or a humidifier... breaking Y won't catch those leaks because those components aren't using Y signals to function.
The only time I see breaking Y as preferable is if the system is an 80% furnace with AC attached to it. In this case, if Y is broken, the heating can still be operational, where breaking R in this case would disable both heating and cooling. This is a bigger deal during those times of the year where both AC and heating may be used, where temperature swings from day to night can be drastic enough for heat and AC to be utilized on the same day.
Mike you would wire the Safety Switch from the Condensate Removal Pump to the yellow wire on your thermostat. Correct?
Yes you can do it like that, unless you have anything else that makes water going to that pump, like a 90% furnace or humidifier, then going to the red 24 v wire would be better.
Very nice sir Europe resturtant use fridge contrl wiring dg need to lern if posbile sir you are explain great how to check component its how to runing how to shurt that is work
You just solved mt issue .
What happens to w once it leads to the air handler but its what activates the PCB to run heat . So W always needs a wire if its for heat. Especially for a reversing vaule
In a heat pump system, W activates the backup heat, in most cases this is going to be heat strips, but could be a furnace or a boiler. This terminal should only turn on heat during defrost cycles or when the heat pump system cannot generate enough heat on its own to reach demand (such as during a big temp difference between room temp and set point).
@@JerseyMikeHVAC i see. Thank you
Hey Sir, I really appreciate your videos, as I'm new to the trade. But in this particular video isn't this the wiring set up for a furnace? I've installed air handlers and the boards aren't set up like this. This reminds me of wiring a furnace. I struggle with wiring an air handler the wires a usually blue and orange. Can you do a video on that kind of air handler? Thanks so much for your time!!
Are you installing heat pumps?
@@JerseyMikeHVAC no heat pump’s just air handler’s. Mostly trane units.
Is the 24v at the thermostat control ac or dc ? From there do I understand correctly that the thermostat control itself does nothing but open/close (relays i presume) the circuit between R and either W/Y/G ? It plays no part in the logics of the heating (or cooling) system such as preheat (running burner for a bit before the fan comes on) and cool down (burner shuts off a bit before the fan does) ?
It's 24v ac. And the rest is correct. Control boards in the units typically take on those roles. Some 2 stage thermostats can alter blower and fan speeds as well as signal 2 stage gas valves in furnaces some smart thermostats will try to increase efficiency by cutting the 24v signal to the control board in and out.
Can you make one wiring carrier with a infinity system
Love your drawing, can you draw a drawing with a heat pump. I have an issue where I have a heat strip that comes on and the system goes down, I don’t think my bleeder is moving enough air and it’s overheating, the three strip elements may be too much heat tripping the sensors
I recently did a few videos on heat strips and heat pump wiring, all fairly recent in my library with drawing of circuits in each.
So in heating mode would the IFM wire and Heating mode wire be jumped together
No, That's done internally in the control module. In this diagram you only need the white wire to provide 24 volts to the W terminal to activate heating mode and the IFM.
Let me ask you, can it also be said that if I understand the wiring first, everything else will fall into place and make sense about all the other major moving parts from a bigger picture perspective?
Yes, I would say that's very true. Every hvac system has a very particular sequence of operation, meaning all of the bigger picture pieces come in and out of play at very particular times. That entire sequence is controlled by the wiring.
So if you know the wiring, you'll learn the sequence. If you know the sequence, you'll learn what each bigger piece does and why it is in that part of the sequence. If you know what each piece does, you'll know how a system works all together and how to better diagnose problems when it isn't working properly.
@@JerseyMikeHVAC Perfect, wiring is where I'll start. Thank you so much! I'm subbed with bell notification, so keep the content coming!
I have an issue. I have an older Maytag electric furnace for a manufactured home. The 4 wires coming from what I believe would be the mother board to splice to the thermostat wires are red, white, green & gray. I have 5 wire thermostat wire. So the only wires being used. Are R/W/G. All of those wires are in their perspective connections on the wall thermostat. I cannot get the blower to come on manually. Also I took the green wire out and turned the heat on and it still turned on with the blower running. What is going on? I just want to be able to turn my blower on to recirc warm air from my pellet stove this fall.
An older unit like that may not have an actual control board, but rather a simple relay board. Normally the green wire activates the relay on the board to kick on the blower, but if that wire is bad, electric heat can still turn on the blower by powering the relay without a 24 volt signal on the green wire. It's a hard wired safety feature.
Another possibility is the relay itself is bad, and that little board with the relay on it will have to be replaced.
If you have an extra wire, use it to connect to the G terminal on the thermostat and connect the other end of that same wire to where the green wire is at or inside the furnace. Basically replace the green wire with one of the unused ones.
That may fix your problem. If not, the relay is likely bad. .
@@JerseyMikeHVAC looks like the relay. Tried an unused wire to the furnace green and still nothing. Thx for help!
Thank you very much for your video. My Green and Red wires has only 13.5Vac. So, the problem should be the control board air-handler, right?
Testing between red and green terminals should give you 24+ volts if the fan is off or 0 volts if the fan is on. Weak voltage sounds more like a weak/loose wire connection or damaged wire.
@@JerseyMikeHVAC Thank you for the response. On your hand draw diagram, is the control board the same as Solid State Time Delay?
@@HsingSun There may be a time delay relay on the control board, but the diagram in this video doesn't go to that depth into the circuitry.
@@JerseyMikeHVAC Thank you for the response. With the thermostat cover off, wires R & C is reading 5.6 volt, is it normal?
@@HsingSun You don't test R to C. You test R to ground to see if you have 24 volts at the R terminal. If you can't reach a ground point from the tstat, test the terminals you're trying to diagnose. If heating isn't working, for example, test R to W. You will have 0 volts if the thermostat is calling for heat and roughly 24 volts if it is off. Same for cooling (R to Y).
If you're still showing somewhere in between 0 and 24+ volts, you either have a bad fuse, a grounded wire (which will also blow the fuse) or a bad tstat.
What isnt working? Heating, cooling? What system do you have? Furnace, air handler, boiler, heat pump?
Do you need the connection from condenser to common in order to send 24 volts to thermostat via common? Or does it come from the air handler board?
Every circuit has to come back to common at some point. T-Stat gets 24v from air handler. T-stat sends out 24v signal to condensing unit either through air handler control board or directly from T-stat (depending how old the system is). From condensing unit 24v comes back on common to air handler to complete the circuit.
@JerseyMikeHVAC I'm needing to install an existing unused c wire. Would I just be able to connect c wire from air handler c connection to thermostat? Or would I need to do anything with the c wire from condenser as well to make c wire to thermostat work?
@@BaseballBigE you can take it straight from the air handler.
Like the pic.
I am wiring in a APCO Fresh Air system. Where would I want to wire it in to? I am assuming that I want it powered on at all times.
Off of the R and C terminals directly, or to the 24 volt side terminals of the transformer inside. Same thing, different spots.
@@JerseyMikeHVAC thank you so much. I just pulled the blower motor apart and it had so much moldy build up on it, so I cleaned it all up. I was thinking of mounting the APCO unit above the blower motor so that it hits the fan and condenser. Is this a good idea or bad? I have a York single phase packaged heat pump outdoor unit.
Got the Low Voltage down pat but you need some Training in the Portrait vs Landscape mode.
Question, what state are you doing HVAC work?
NJ
I have a tstat wire going to air handler and a second wire going from air handler to my oil boiler. So that wire has 24v entering the boiler. Add to that the boilers 24v, I am getting 50v on the zone valve...which fries the head. Seems like I am miswired? Tstat wire coming from air handler should have no voltage on it until the tstat kicks in and activates the boiler. Am I correct? Issues began after a new boiler was installed.
Is the boiler tied into W at the air handler?
It wasn't! Was tied to Common instead, hence the constant 24v. I rewired it ti W, now all is good! Thank You!!!! For both the knowledge and for replying quickly.
Is the wiring the same for residential and commercial?
Not really. There are similarities in the concept, but commercial tends to be a lot more complex.
What if it's a 2 wire system..red and white. It only works on heat and auto fan.
I installed a nest thermostat on the 2.
It tell me to run a c wire.
Is the c port on the thermostat itself putting out 24v? And grounds out at the control board?
How is the fan coming on when I only have Rh and white?
C terminal on the stat does not put out 24v. When a wire is connected from C at the stat to C at the control board, it just completes a dedicated circuit with the R terminal, and the Nest recharges off of that circuit. So R is your 24v FROM the transformer and C is the common BACK TO the transformer. Some smart thermostats are what is called "power stealing", which means the stat will charge off of the closed W circuit during calls for heat (or the closed Y circuit during calls for cooling), both of which eventually make their way back to common at the transformer. When a stat needs a common wire, it is not getting enough power to recharge off of the heating or cooling cycles, so needs its own charging circuit.
On newer control boards, a signal for heating or cooling (Y or W) will activate the blower motor without the need of a signal from G. You would only need a wire on the G terminals if you wanted to run the fan independently just for air recirculation.
@JerseyMikeHVAC thank you for responding.
I actually went and got the correct wires today and pulled it to the furnace.
Everything works as it should.
What if I don't have a control board? I'm trying to wire the thermostat for a mobile home packaged unit
Same here. Picked up a smart thermostat from the local power company, since they were on sale! Wired it up.
"C wire not detected."
After much Google searching and a few TH-cam videos later, I "just need to connect the C wire, to C port, on the control board."
Power off all the circuit breakers, open up the unit panel… and there is no control board.
On some older systems the common is actually the chassis of the unit itself. Common is ground. I would have to see the schematics of the unit to know for sure, but sometimes a clue is if you can trace a wire off of the 24 volt side of the transformer directly to a ground screw.
I installed a brand new 2 ton Heat Pump (Yes Goodman) and I set it up to cool the house. It worked for a few (3) days and then out of nowhere it stopped completely. I check the thermostat and not getting 24V at all. I push the button for the contactor and compressor start to work, but it did not engage the fan so is not pushing air thru the vents. Any Ideas where I should look at? Thanks. Daniel.
Check the fuse on the control board in the air handler. Might have a short somewhere in the wiring and popped it.
@@JerseyMikeHVAC this unit doesn't have a fuse on the control board or anywhere else. It's odd. Following your diagram I'm going to test each circuit. Cause the contactor doesn't 24V either.
@@JerseyMikeHVAC thanks
If it doesn't have a fuse I would tie one in. I've come across a few that didn't have one and did that to protect the transformer. Might want to see if that's giving you 24v too.
@@JerseyMikeHVAC I will. Thanks.
any idea what would make my goodman 3ton unit keep running after it reaches temp in house. I have replaced thermostat no change also had to replace fan board because it burnt up last week
Is it only the outdoor compressor continuously running, only the indoor blower running or both running after reaching temp?
@@JerseyMikeHVAC the compressor contactor as well as the blower motor outside stays running when i checked fan board i still have 24v on green keeping blower motor running i assume the temp inside house could be 78 and the cool setpoint will be reading 78 but it been running for 35 min since the 2 numbers matched thats not normal
never had any issue till last week smelt a burning smell and the fan board relay had burned up i replaced my board with an oem upgrade board and stuff started goin haywire never had this issue before
i have been an electrician for 30 yrs and iam kinda feeling lost
Take air temperature readings at the return grill and the closest supply run coming off of the unit. What are those 2 temperatures reading? It should be roughly a 20 degree difference. One possibility is that if that temp differential is considerably lower than that, it could be an airflow problem (dirt, or maybe ice build up) that is keeping the system running much longer cycles than usual, putting a lot more strain on the blower motor as a result. Let me know.
I need help figuring out why I have no power to my thermostat, when all the transformers are putting out 24 volts. It's in an apartment building and I've been scratching my head for days now. PLEASE HELP!!!
Is it just one thermostat not getting power? If so, I would first test for continuity on the 2 wires between the thermostat and its respective zone valve.
1. Kill the power on the boiler.
2.Disconnect both tstat wires from that particular thermostat at the zone valve it goes to and wire nut those 2 wires together.
3. Disconnect both wires at the tstat and test for continuity.
4. If your meter doesnt beep there's you're problem. One of those wires are pinched, chewed or grounded.
So where does the wiring to the capacitor come in to play?
Which one?