This is an endorsement for gas pressure switches. Don't tamper with or replace with generic brands. If something weird happens with the pressure in the combustion chamber the furnace won't fire. A good brand of CO detector is a must.
There is no guarantee the pressure switch will detect the failure but your point is well taken. If a fire or fatality happens and the pressure switch has been tampered with or is not a factory part, the tech that made the adjustment would find he is in great trouble. GFM
Great channel, thank you for what you do! It helped me remove my blower. Carrier 580MVP (2003), Code 13 FRS keeps popping. Filter was clean, replaced inducer motor, removed blower and checked the heat exchanger from below, looks in great shape, no corrosion or dust buildup. I rebuilt the PVC intake and exhaust last year but checked to make sure they are clean, it's a pretty short run to the outside. I will wipe off any dust on the blower and heat exchanger with a wet towel but there isn't much on them. I don't notice any visible flame roll out and the flame doesn't really change when the blower kicks on. I don't know what else to do, do you have any ideas?
The troubleshooting guide said to check: 24-vac across PL1-6 and Com and PL1-8 and Com, it was higher than that, like 25 or 26volts but i don't know if that is good or bad. I'm still teaching myself how to use this multimeter so tonight I will check continuity across limit switch LS and the FRS. Thanks four your help, I just don't trust the furnace companies around here. Tried to charge me $500 for a condensate pump last year and $1000 to replace pvc pipe concentric exhaust kit...
Absolutely nothing. All burners lit normally, no flame rollout, no CO, no pressure switch cutout, and no limit cutout. A rather scary situation as the crack is quite large and could, if it displaced a little, could cause a CO problem. GFM
If you want to try the flashlight trick (not the most effective way), place it in the supply plenum and darken the room. You may be able to see the light from inside the heat exchanger. GFM
cracks like this are exactly why we at our company do a visual inspection of every heat exchanger on every call we go out on. AHRI says if there's a crack, it should be replaced.
We pull blowers on every call, and on American Standard we also look through the coil access (when it's a down flow) because that's where we go to see the cracks. Right above the mouth of the heat exchanger on the side where it's crimped together, right up against the front of the furnace. We are finding cracks on 2 and 3 year old equipment, even if it has .5 total external static, or whatever static it requires.
So I see that you found this furnace in the junk pile. I wonder why it was discarded. In a normal routine furnace inspection would the technician go to extent that you did to find a cracked exchanger when there were no symptoms? I saw your other vid on cracked heat exchanger scams and wonder if maybe this was a case of a scam that turned out to be cracked after all.
You missed the point of the scam video. A service tech that condemns a furnace without doing a thorough check of the heat exchanger is only increasing his bottom line without any value to the customer. GFM
While i would red tag this unit i dont believe that it would cause CO related problems. If we take a furnace and run a combustion analysis chancing are good if it is firing properly we will have somewhere around 30ppm or less running....But lets use an extreme situation and say that this furnace is running 600ppm calculated by combustion analysis via flue. That value is the combination of several things in the exhaust but lets just act like there is only oxygen and carbon monoxide. we have roughly 25cfm being pulled through that flue by the inducer. 600ppm with 25cfm. now lets look at that furnace, based on burners we can assume its at least a 4 ton unit and in heat mode is moving 1000cfm. So lets do a little math, 600ppm divided by 25 cfm equals 24ppm per 1cfm. lets assume that the hole in that heat exchanger was huge and all the combustion air was mixing with the blower motor air. so that would be 600ppm divided by 1000cfm which equals 0.6ppm per cfm....unless I am looking at this wrong?
Your calculations may be correct. However, they are no guarantees here. This crack produced no CO at all and did not affect the flame. More than anything, this video is there to show heat exchanger integrity may be close to impossible to determine without a very thorough examination. GFM
I simply say this, not because of anything you said or this video. But because of all the companies i follow around using carbon monoxide scare tactics. In hopes that anybody viewing this video might understand that it is not as dangerous as many people like to say. I personally would still redtag unit, but there is plenty of really good techs out there that wouldnt because they understand the real threats are minimal...
I agree that many of the CO warnings are scams. In fact I did a video on heat exchanger scams. I have heard techs say that if the furnace is over 15 years old, it almost guaranteed it will produce fatal CO. I like to think I determined heat exchanger condition in light of its potential danger to the customer and not to my bottom line. GFM
the problem is that co accumulates in the body over time, so a small exposure over long periods can cause sickness/death, even more prevalent in infants and elderly.
yes indeed it can, but not that small of exposure is going to do anything. you will be very lucky to find a meter that will read anything coming out of a supply vent due to dilution from air. you may find a personal meter will go off after someone has been cooking or a water heating that is drafting into a home but very rarely a furnace. I was surprised to find out just recently that OSHA allows for 40ppm exposure in a work environment for a period of 8 hours a day! way more than i expected. When we are talking about a cracked HX emitting .05% CO into a house it isnt going to do anything to anybody.
grayfurnaceman wouldn't you be looking for increased oxygen in the flue gas not CO? Or are you saying the crack causes disruption in the air/fuel ratio causing CO? Similar to if you have very elevated levels of excess air.
I think I tested this one once, but never did a vid on it. You can get increased 02 but it has to be pretty bad unless you can check each tube. The dangerous ones are from disruptions in the flame which will make CO. I will probably do a video on combustion analysis of this furnace. GFM
Of course you can. The furnace is removed from the ductwork. The point of the video is that without removing the furnace from the ductwork, it is quite hard to find the crack. GFM
I like flash lights with a strobe function. The strobes really jumps out at you and Makes it easy to see
Could help.
GFM
this is why I wish...wish it was code to put a transition with an access door between the furnace and the coil
Would be nice.
GFM
dpeagles I agree with you! it would certainly be better.
They do it’s called a humidifier. Lol
Old Bard furnaces had this
hats off to you sir ! You definitely have the knowledge and skills to be a great HVAC technician!
Thanks for the support.
GFM
This is an endorsement for gas pressure switches. Don't tamper with or replace with generic brands. If something weird happens with the pressure in the combustion chamber the furnace won't fire. A good brand of CO detector is a must.
There is no guarantee the pressure switch will detect the failure but your point is well taken. If a fire or fatality happens and the pressure switch has been tampered with or is not a factory part, the tech that made the adjustment would find he is in great trouble.
GFM
Great channel, thank you for what you do! It helped me remove my blower. Carrier 580MVP (2003), Code 13 FRS keeps popping. Filter was clean, replaced inducer motor, removed blower and checked the heat exchanger from below, looks in great shape, no corrosion or dust buildup. I rebuilt the PVC intake and exhaust last year but checked to make sure they are clean, it's a pretty short run to the outside. I will wipe off any dust on the blower and heat exchanger with a wet towel but there isn't much on them. I don't notice any visible flame roll out and the flame doesn't really change when the blower kicks on. I don't know what else to do, do you have any ideas?
The troubleshooting guide said to check: 24-vac across PL1-6 and Com and PL1-8 and Com, it was higher than that, like 25 or 26volts but i don't know if that is good or bad. I'm still teaching myself how to use this multimeter so tonight I will check continuity across limit switch LS and the FRS. Thanks four your help, I just don't trust the furnace companies around here. Tried to charge me $500 for a condensate pump last year and $1000 to replace pvc pipe concentric exhaust kit...
So what were your symptoms?
Absolutely nothing. All burners lit normally, no flame rollout, no CO, no pressure switch cutout, and no limit cutout. A rather scary situation as the crack is quite large and could, if it displaced a little, could cause a CO problem.
GFM
most cracked heat exchangers will show no symptoms. most cameras are not adequate to inspect unless you have an infrared camera like the inspector
Gary where do I put the flashlight to see if there's any light coming through the heat exchanger
If you want to try the flashlight trick (not the most effective way), place it in the supply plenum and darken the room. You may be able to see the light from inside the heat exchanger.
GFM
grayfurnaceman thank you Gary for the information that did help a lot thank you I'm just trying to learn. Have a good one my friend
Does the O2 change on a combustion test when the blower comes on.
I will be doing a combustion test on this furnace soon.
GFM
Yes, a combustion test should always be done, if not you are only guessing.
Could you have pulled the blower and shown a light up thru the bottom and seen the crack?
Its a 90+ furnace.
GFM
So what led you to believe there was a crack in the first place
The furnace had been replaced and I saw it in the junk pile.
GFM
Oh ok that makes sense. I'm new to the trade so I'm still having trouble finding these little buggers
Sometimes very tough to find even for the experienced techs.
GFM
cracks like this are exactly why we at our company do a visual inspection of every heat exchanger on every call we go out on. AHRI says if there's a crack, it should be replaced.
The only sure way of finding this crack will be to remove the supply plenum. It is not visible from the burner tubes, even with a camera.
GFM
We pull blowers on every call, and on American Standard we also look through the coil access (when it's a down flow) because that's where we go to see the cracks. Right above the mouth of the heat exchanger on the side where it's crimped together, right up against the front of the furnace. We are finding cracks on 2 and 3 year old equipment, even if it has .5 total external static, or whatever static it requires.
So I see that you found this furnace in the junk pile. I wonder why it was discarded. In a normal routine furnace inspection would the technician go to extent that you did to find a cracked exchanger when there were no symptoms? I saw your other vid on cracked heat exchanger scams and wonder if maybe this was a case of a scam that turned out to be cracked after all.
You missed the point of the scam video.
A service tech that condemns a furnace without doing a thorough check of the heat exchanger is only increasing his bottom line without any value to the customer.
GFM
Great vid!!! Thank you Sir~~~~ 😄😄😄
This was the very first furnace I had to take apart
While i would red tag this unit i dont believe that it would cause CO related problems. If we take a furnace and run a combustion analysis chancing are good if it is firing properly we will have somewhere around 30ppm or less running....But lets use an extreme situation and say that this furnace is running 600ppm calculated by combustion analysis via flue. That value is the combination of several things in the exhaust but lets just act like there is only oxygen and carbon monoxide. we have roughly 25cfm being pulled through that flue by the inducer. 600ppm with 25cfm. now lets look at that furnace, based on burners we can assume its at least a 4 ton unit and in heat mode is moving 1000cfm. So lets do a little math, 600ppm divided by 25 cfm equals 24ppm per 1cfm. lets assume that the hole in that heat exchanger was huge and all the combustion air was mixing with the blower motor air. so that would be 600ppm divided by 1000cfm which equals 0.6ppm per cfm....unless I am looking at this wrong?
Your calculations may be correct. However, they are no guarantees here. This crack produced no CO at all and did not affect the flame. More than anything, this video is there to show heat exchanger integrity may be close to impossible to determine without a very thorough examination.
GFM
I simply say this, not because of anything you said or this video. But because of all the companies i follow around using carbon monoxide scare tactics. In hopes that anybody viewing this video might understand that it is not as dangerous as many people like to say. I personally would still redtag unit, but there is plenty of really good techs out there that wouldnt because they understand the real threats are minimal...
I agree that many of the CO warnings are scams. In fact I did a video on heat exchanger scams. I have heard techs say that if the furnace is over 15 years old, it almost guaranteed it will produce fatal CO. I like to think I determined heat exchanger condition in light of its potential danger to the customer and not to my bottom line.
GFM
the problem is that co accumulates in the body over time, so a small exposure over long periods can cause sickness/death, even more prevalent in infants and elderly.
yes indeed it can, but not that small of exposure is going to do anything. you will be very lucky to find a meter that will read anything coming out of a supply vent due to dilution from air. you may find a personal meter will go off after someone has been cooking or a water heating that is drafting into a home but very rarely a furnace. I was surprised to find out just recently that OSHA allows for 40ppm exposure in a work environment for a period of 8 hours a day! way more than i expected. When we are talking about a cracked HX emitting .05% CO into a house it isnt going to do anything to anybody.
good stuff, thanks ...
You would think that as the heat exchanger got hot that the crack would open up a bit.
Doesn't seem to.
GFM
Combustion analyzer?
Tried it. No CO.
GFM
dye test?
grayfurnaceman wouldn't you be looking for increased oxygen in the flue gas not CO? Or are you saying the crack causes disruption in the air/fuel ratio causing CO? Similar to if you have very elevated levels of excess air.
In order to use the dye test, you would have to remove the ductwork. If it is removed, you can see the crack.
GFM
I think I tested this one once, but never did a vid on it. You can get increased 02 but it has to be pretty bad unless you can check each tube. The dangerous ones are from disruptions in the flame which will make CO. I will probably do a video on combustion analysis of this furnace.
GFM
I use the inspector camera that has an infrared camera and can focus better than any snake camera.
That could work.
GFM
Part number ?
if not detected
so why do they make these heat exchangers that don't last that long and can give u carbon monoxide poisoning
This furnace is at least 20 years old
BRUH I CAN SEE IT
Of course you can. The furnace is removed from the ductwork. The point of the video is that without removing the furnace from the ductwork, it is quite hard to find the crack.
GFM
Cocomelon