Heil furnace troubleshooting help

[belvedere]

Hoping someone can help with our house furnace. It is a Heil 95% installed in Feb 2016.

A couple years ago, in the late fall, it would stop and restart, showing a Code 3 (pressure switch). The issue gradually got worse, so I called the guy who installed it. He found water in the combustion fan housing, so took it apart and cleaned everything out, and made some adjustments to the condensate drain as he thought it wasn't sloped correctly. It worked fine after that, but the outdoor temp also turned much colder the next day (that detail is relevant as I'll explain). Since that time, it has shown a consistent pattern: it will frequently stop (code 3) and restart, but only when the outdoor temp is above maybe 20-25F. Once it turns colder than that, the furnace will happily run without a hiccup. The change is instant: if it's 30F one day it will act up, then run fine the next day if the temp drops to 10F. The only thing I could think of is that it has something to do with humidity. I should also add that it does not draw combustion air from outside, but from the surrounding air (unfinished basement). Also, at one point I tried a new pressure switch assy, but that didn't help.

Any advice appreciated!

 

[rerod]

I'm only guessing drawing combustion air from inside is your problem. I installed furnaces for 17 years, years ago and always pulled combustion air from outside. But I'm reaching..

 

[couch67]

Hoping someone can help with our house furnace. It is a Heil 95% installed in Feb 2016.

A couple years ago, in the late fall, it would stop and restart, showing a Code 3 (pressure switch). The issue gradually got worse, so I called the guy who installed it. He found water in the combustion fan housing, so took it apart and cleaned everything out, and made some adjustments to the condensate drain as he thought it wasn't sloped correctly. It worked fine after that, but the outdoor temp also turned much colder the next day (that detail is relevant as I'll explain). Since that time, it has shown a consistent pattern: it will frequently stop (code 3) and restart, but only when the outdoor temp is above maybe 20-25F. Once it turns colder than that, the furnace will happily run without a hiccup. The change is instant: if it's 30F one day it will act up, then run fine the next day if the temp drops to 10F. The only thing I could think of is that it has something to do with humidity. I should also add that it does not draw combustion air from outside, but from the surrounding air (unfinished basement). Also, at one point I tried a new pressure switch assy, but that didn't help.

Any advice appreciated!

What a timely post. I've been dealing with pretty much the same issue, but with a different furnace. Its a Frigidaire (Nordyne) 95%.My furnace does pull air in from the outside. Problem started in the fall, and has been intermittent since then. Furnace repair crew who installed it originally about 9 years ago, have been by 5 or 6 times to diagnose. Have run every test possible, and have changed pressure switches, inducer fan, and control board.

The symptoms - when furnace cycle starts, the inducer fan spins up, then burners fire up. After 20 seconds or so, inducer fan switches to low speed, and then burners shut off and the cycle starts over. No fault indicators to tell what is wrong, but a few times I have seen where the inducer fan will run at high speed and then stop, and the fault code shows 'pressure switch open'. The furnace will continue to cycle in this fashion until something clears up and it runs a successful heating cycle.

I have noticed the same thing- I don't think it happens at all when when its very cold out, and is at its worst when its just below freezing outside. Happens the most in the morning, a few hours or so after the furnace has brought the house up to 'Daytime' temperature.

One thing I have recently discovered - when the furnace is in this failure mode, if I do the following steps (leave the furnace power on):

- unplug the tube that connects the pressure sensor tube at the condensate drain pan
- push a small 22 gauge wire into the ****** on the drain pan, just a few inches
- then remove the wire and and reinstall the pressure tube

After doing this, and waiting for the furnace to cycle again, it fires right up as if nothing is wrong. It might run without a hiccup for a few hours or a few days. I'm not sure what this could be doing, but I'm thinking condensation on the vertical wall inside the pan is dripping down and blocking the pressure port, which is very small (like < 1/8" ID). I think inserting the wire breaks the suction of the water blocking the pressure port. I want to test this a bit further, then call my furnace guys back in to see how to resolve this.

Sorry for the long post but hopefully this helps in some way.

 

[Perroflojo]

The condensate line all the way to the draft inducer needs to be kept clean. I would run the intake pipe to the outside.

The draft inducer has some ******* where they measure the capacity make sure the ******* are not clogged w/ stuff.

I do have a Heil Furnace but from 2004

 

[rerod]

I had a issue that was diffucult to diagnose when I first installed my carrier infinity. It kept locking out, but I forgot what the fault was.. I installed a second transformer in parallel of course, and lock outs stopped. Apparently, the supplied transformer's amperage wasnt enough for the board to perform reliably.

 

[fitter30]

Have you cleaned the condensate drain in the blower compartment?

 

[belvedere]

I'm only guessing drawing combustion air from inside is your problem. I installed furnaces for 17 years, years ago and always pulled combustion air from outside. But I'm reaching..

Thanks for the reply. The reason I don't think this is the problem, is because it ran the first 3-4 years with no issues.

What a timely post. I've been dealing with pretty much the same issue, but with a different furnace. I

One thing I have recently discovered - when the furnace is in this failure mode, if I do the following steps (leave the furnace power on):

- unplug the tube that connects the pressure sensor tube at the condensate drain pan
- push a small 22 gauge wire into the ****** on the drain pan, just a few inches
- then remove the wire and and reinstall the pressure tube

Sorry for the long post but hopefully this helps in some way.

Very interesting...thanks for posting the details of your similar issue. I'll have to take a closer look at mine when I have a little time, but I don't remember an actual drain pan (I could be wrong).

Our daytime temps had been in the 20s and 30s, so the furnace was acting up. Yesterday it got colder, and the furnace worked fine. Today it is warmer, and the problem is back! So strange how outside temps affect it so consistently, when no outside air is drawn into the furnace.

The condensate line all the way to the draft inducer needs to be kept clean. I would run the intake pipe to the outside.

The draft inducer has some ******* where they measure the capacity make sure the ******* are not clogged w/ stuff.

I do have a Heil Furnace but from 2004

Have you cleaned the condensate drain in the blower compartment?

Thanks for the replies, guys. I have cleaned it in the past, but not lately. See my message above to couch67: the problem consistently disappears when the outdoor temp drops below maybe 15F or so. So strange!

 

[DennisK59]

Remove the condensate drain off the inductor blower, I clean it with oven cleaner and Q-tips real well, reinstall the drain collector with a slight downhill slope, 5-10 degrees.

 

[couch67]

Very interesting...thanks for posting the details of your similar issue. I'll have to take a closer look at mine when I have a little time, but I don't remember an actual drain pan (I could be wrong).

Our daytime temps had been in the 20s and 30s, so the furnace was acting up. Yesterday it got colder, and the furnace worked fine. Today it is warmer, and the problem is back! So strange how outside temps affect it so consistently, when no outside air is drawn into the furnace.

Thanks for the replies, guys. I have cleaned it in the past, but not lately. See my message above to couch67: the problem consistently disappears when the outdoor temp drops below maybe 15F or so. So strange!

I learned the proper term for what I was calling a drain pan - its called a condensate collector box. On my furnace, its mounted to the face of the heat exchanger, and collects the condensation that is generated. Furnace guys replaced it this week (they confirmed there was a tech bulletin to replace it, but it was never done on my furnace). After replacing it, the inducer would not pull enough vacuum to continue the heat cycle. Turns out that part of the tech bulletin included repositioning the secondary heat exchanger (I think to increase the drain angle), and all the banging around turned a mostly-clogged heat exchanger into a very-clogged heat exchanger. Tech explained that this was the likely culprit the whole time. Not sure if the collector box was a red herring, or a confounding factor. I'm sure it had to be part of the problem since my temporary fix would get things running again.

So now we do not have a furnace, and heating with space heaters and our fireplace. Replacement is supposed to happen on Monday.

 

[jlrut]

Heil is Carrier. There is a TSB on this issue. Furnace needs a good pitch towards the front, updated control board and inducer assembly. The inducer has a modified port for the pressure switch. Water blocks the port and gets into the tubing. The fix in the control board is a 20 second delay to respond the pressure switch issues. Proceed with caution. I think they are a engineered disaster.

 

[belvedere]

I learned the proper term for what I was calling a drain pan - its called a condensate collector box. On my furnace, its mounted to the face of the heat exchanger, and collects the condensation that is generated. Furnace guys replaced it this week (they confirmed there was a tech bulletin to replace it, but it was never done on my furnace). After replacing it, the inducer would not pull enough vacuum to continue the heat cycle. Turns out that part of the tech bulletin included repositioning the secondary heat exchanger (I think to increase the drain angle), and all the banging around turned a mostly-clogged heat exchanger into a very-clogged heat exchanger. Tech explained that this was the likely culprit the whole time. Not sure if the collector box was a red herring, or a confounding factor. I'm sure it had to be part of the problem since my temporary fix would get things running again.

So now we do not have a furnace, and heating with space heaters and our fireplace. Replacement is supposed to happen on Monday.

Heil is Carrier. There is a TSB on this issue. Furnace needs a good pitch towards the front, updated control board and inducer assembly. The inducer has a modified port for the pressure switch. Water blocks the port and gets into the tubing. The fix in the control board is a 20 second delay to respond the pressure switch issues. Proceed with caution. I think they are a engineered disaster.

I'm not sure why I didn't see these replies when they were posted a year ago - my apologies, and thank you guys for the info!

couch67: I hope the furnace work went well and solved your issue!

jlrut: Do you know where I can find more info on this? Maybe a link? Thanks!

 

[jlrut]

I'm not sure why I didn't see these replies when they were posted a year ago - my apologies, and thank you guys for the info!

couch67: I hope the furnace work went well and solved your issue!

jlrut: Do you know where I can find more info on this? Maybe a link? Thanks!

https://hvac-talk.com/vbb/attachment.php?attachmentid=757521&d=1484536713

New Carrier & ICP 35" Condensing Furnace Pressure Switch Errors

New Carrier & ICP 35" Condensing Furnace Pressure Switch Errors

www.hvactechgroup.com

Some good info and discussion. These furnaces are failing like the previous generation heat exchangers. The updated control board has to have 20 seconds of continuous open pressure switch before it shuts down for a pressure switch failure and throw a code. Bad combo in my opinion. Poor quality heat exchanger with a built in safety delay. Like I said before, proceed with caution on any Carrier built equipment. Carrier has been a dumpster fire for decades.

 

[belvedere]

Some good info and discussion. These furnaces are failing like the previous generation heat exchangers. The updated control board has to have 20 seconds of continuous open pressure switch before it shuts down for a pressure switch failure and throw a code. Bad combo in my opinion. Poor quality heat exchanger with a built in safety delay. Like I said before, proceed with caution on any Carrier built equipment. Carrier has been a dumpster fire for decades.

Thanks so much for the info!

 

[MWPollard]

The ideas here helped me figure out my issue, and maybe it will help someone else.

On my Heil unit, there are two pressure sensors back-to-back. (Note that they aren't labeled. They are thin disks with one hose nozzle and a couple of wires.) When checking to make sure both hoses were clear, I found on the inner one, which had a thick square hose, the sensor had a reducer in the nozzle that is extremely small, such that a stick pin wouldn't fit. I removed the reducer, reattached the hoses, closed the other panel to re-power the unit, and it kicked right on.

Apparently the reducer was plugged, and it's too small to clean easily. This happened after having excessive condensation because the drain line froze and backed up, and the hose may have gotten water when it was only expecting air.

I found this thread when looking for tips to clear out the water. I spun the impeller by hand while holding a shop vac to the outlet. After some of the water came out, the vacuum was enough to spin the impeller. Once the unit kicked on, it threw water everywhere, though only outside the unit...

 

[fitter30]

The ideas here helped me figure out my issue, and maybe it will help someone else.

On my Heil unit, there are two pressure sensors back-to-back. (Note that they aren't labeled. They are thin disks with one hose nozzle and a couple of wires.) When checking to make sure both hoses were clear, I found on the inner one, which had a thick square hose, the sensor had a reducer in the nozzle that is extremely small, such that a stick pin wouldn't fit. I removed the reducer, reattached the hoses, closed the other panel to re-power the unit, and it kicked right on.

Apparently the reducer was plugged, and it's too small to clean easily. This happened after having excessive condensation because the drain line froze and backed up, and the hose may have gotten water when it was only expecting air.

I found this thread when looking for tips to clear out the water. I spun the impeller by hand while holding a shop vac to the outlet. After some of the water came out, the vacuum was enough to spin the impeller. Once the unit kicked on, it threw water everywhere, though only outside the unit...

The burner control shoould have a red light that flashes for operating and faults. Usually right on its label