Propane furnace freezing up

[MUD DAWG]

Man, talk about frustrating. Here I am woken up at 3 am by a freezing house again. Unfortunately the pressure switch didn't solve the issue.

When the furnace failed to fire, I checked voltage, and I got 27.x VAC going to the valve. I turned off and on the gas valve, and turned power back to the furnace, only to have it fire away again. This time I didn't even use a hair dryer. But the cabinet door was open, and I don't know if it was the room air pressure, or temperature that might've caused it to fire this time.

With the cabinet door closed, and air pipe from outdoors, I set thermostat down a few degrees. Waited 10 minutes, and raised the thermostat again, and the furnace fired again. But if it goes off for an hour, it won't fire back up again.

Friday's temps are supposed to drop to -22F, and this isn't helping. I'll have to just draw air from the basement in the meantime. I can't really see anything out of spec for the piping.

 

[bobbyjean]

mud dog- did not read all the replies on thread ...
what size are the intake/exhaust
temp rise across unit-
condensate line/trap -ok
what type of termination was used on exhaust -does it have a birdscreen
air filter's -clean...

 

[naturalgas]

Mud, if you have 24v at Gas valve it should be firing up. Sounds now like the gas valve is hanging up. I would let the installer know you had 27v at valve and it was not firing. He should change out gas valve. So it’s either a bad gas valve or propane delivery issue to valve. PM me I’ll give you my number to call me.


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[MUD DAWG]

mud dog- did not read all the replies on thread ...
what size are the intake/exhaust
temp rise across unit-
condensate line/trap -ok
what type of termination was used on exhaust -does it have a birdscreen
air filter's -clean...

Hi Bonbyjean.

- 2" PVC piping was used. Say 20 feet for intake, and 25 exhaust if I account down the bends.

- what temp rise across unit do you mean? The difference between the air drop and plenum going up?

- Condensate line and trap are free and clear.

- The exhaust termination has no screen at all, and aside from an icicle running down, it's free and clear

- Air filter is clean

 

[gungatim]

Sorry, to add, cut the intake and test drawing warmer air from inside. You could reattach after.

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I had to do that on mine, hack saw and duck taped back together (theydo make a rubber coupler sleeve) that's how I found out the previuous tech installed the wrong pressure valve, they are all adjusted differently.

 

[MUD DAWG]

Mud, if you have 24v at Gas valve it should be firing up. Sounds now like the gas valve is hanging up. I would let the installer know you had 27v at valve and it was not firing. He should change out gas valve. So it’s either a bad gas valve or propane delivery issue to valve. PM me I’ll give you my number to call me.


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NG. What else cause a propane delivery issue? I mentioned to the installer the gas valve might be sticking, but he doesn't think it is. But did say if the pressure was switch was proving, then no gas would get delivered.

Funny thing, this morning, I didn't need to heat it up with the hair dryer. After I checked the voltage, I just turned off and on the switch on the valve, reset power to furnace, and with the cabinet open, the furnace fired back up.

I'll send you a PM. Thank you for trying to help.

 

[MUD DAWG]

Here are some pictures. Maybe someone with a sharp eye can spot something the installer and I are missing.

BTW. I asked the Installer to call Trane tech support. I wonder if I can call them myself as well? Or is it better to just let the installer do it, specially if it's a warranty issue they need to deal with.

 

[OccupantRJ]

Blow through both those PVC pipes with the hair dryer to see if you get a melted ice surprise. What is creating that icicle?

 

[RAM2940]

Your installer needs to hook a manometer up to the pressure switches to see if the pressures are borderline to the pressure switch. When you start adding and subtracting lenghs of intake air pipe you start changing the pressure by small amounts. I went through a intermittant pressure switch issue on a American Standard it would fail at the pressure switch i went through adding and subtracting pipe but had manometer hooked up, watched pressures change , yours will get to the point of opening the gas valve. I Eventually found a crack in the heat exchanger, I think you have a sticking gas valve.

 

[66cj225]

Thinking gas pressure problem here. If you were outdoors, a gas man would turn on the supply and and hear what you got. If there's water in the tubing or a kink, the low pressure will make it a no go. A manometer installed (at the drip leg) would show gas pressure static and operating. What was the problem that caused the replacement heater?

 

[mooseracing]

Thinking gas pressure problem here.

Possible, check the wiring diagram but alot of the newer furnaces will throw a code for low gas.

As cold as it has been, I had to wrap the draft inducer housing and the run of condensate drip line in heat tape to keep my working. Mine kept throwing a flame rollout code though, when things were freezing.

 

[RAM2940]

You hook a manometer up to the pressure switches to see what the induced draft motor is pulling. Basically testing correct draw through heat exchanger. When you start adding and subtracting lenghs of pipe you slightly change the pressure across the heat exchanger.

 

[MUD DAWG]

Your installer needs to hook a manometer up to the pressure switches to see if the pressures are borderline to the pressure switch. When you start adding and subtracting lenghs of intake air pipe you start changing the pressure by small amounts. I went through a intermittant pressure switch issue on a American Standard it would fail at the pressure switch i went through adding and subtracting pipe but had manometer hooked up, watched pressures change , yours will get to the point of opening the gas valve. I Eventually found a crack in the heat exchanger, I think you have a sticking gas valve.

Thinking gas pressure problem here. If you were outdoors, a gas man would turn on the supply and and hear what you got. If there's water in the tubing or a kink, the low pressure will make it a no go. A manometer installed (at the drip leg) would show gas pressure static and operating. What was the problem that caused the replacement heater?

Yup, when the installer comes back, I'll definitely have him break out the manometer and measure everything. I'd do it myself, but I'm not a gas guy, and I'd rather not go where I shouldn't.

Member NaturalGas was kind enough to call me and he too thinks the gas pressure might be a little, or the gas valve is iffy. We're gonna focus our efforts there.

The reason this furnace was installed, is that I switched over from oil to propane heat.


Thanks for all the help guys, much appreciated. We really have to get this ghost out of the machine soon.

 

[gungatim]

I doubt gas valve is freezing up. It sounds like your pressure switch is not closing consistently on a call for heat .which will be controlled by moving air smoothly from inducer operation. You had said if you took intake air from inside it works fine,so your problem should be in the intake piping of Pfc.


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this. disconnect the hose from the pressure switch to the air intake plenum and see what you get. theres a good youtube video on these valves and how they vary considerably in their sensitivity over temp.

 

[66cj225]

You may not be a gas man but you are the owner (and victim). Your gas valve is not the first device in line here, the regulator at the tank is. If that regulator is not performing, neither will your burner. A quick remedy could be a 100 pounder (or whatever kilogram) with a different regulator to prove the point out but the manometer is a lot less work. Gas Co should prove to you that their equipment is working under load (and temperature).

 

[MUD DAWG]

You may not be a gas man but you are the owner (and victim). Your gas valve is not the first device in line here, the regulator at the tank is. If that regulator is not performing, neither will your burner. A quick remedy could be a 100 pounder (or whatever kilogram) with a different regulator to prove the point out but the manometer is a lot less work. Gas Co should prove to you that their equipment is working under load (and temperature).

The reason I'm discounting the gas supply issue, is that:

1) I don't see any ice up at the 2 regulators
2) I cracked open the union closest to the furnace, and I had gas flow
3) As long I draw warmer air from the basement, furnace will run tip top.

I'm thinking if it was a gas supply issue, I'd constantly be having the problem, regardless of where the furnace was in-taking air. But this isn't to say the pressure might be a little lower now, and isn't meeting the minimum when inside of the furnace is cold like that outside air. At some point, I'll call the gas company to measure again, but it sounds very likely a furnace problem.

 

[u3b3rg33k]

Take a look up inside your inlet pipe outdoors. make sure it's not closing up with frost. it can happen.

since both your intake and exhaust piping are next to each other, wind shouldn't be a factor - it shouldn't be pushing cold air down the pipe into the furnace while it's off (this is possible if for some reason they were installed too far apart/on opposite sides of the house).

I would like you to place a min-max thermometer in the furnace while the door is on for a while. if the inside of the cabinet stays above 32F, then freezing shouldn't be an issue. I would be surprised if the gas valve was dropping much below ambient temperature. there should only be airflow in the cabinet while the inducer fan is running, and it should basically go from the inlet pipe into the burner assembly.

Even if you have cold air feeding the furnace, the air sitting in the inlet pipe should be above outdoor temp as PVC isn't that good an insulator - so it should be warm until the furnace has been running.

 

[MUD DAWG]

Take a look up inside your inlet pipe outdoors. make sure it's not closing up with frost. it can happen.

since both your intake and exhaust piping are next to each other, wind shouldn't be a factor - it shouldn't be pushing cold air down the pipe into the furnace while it's off (this is possible if for some reason they were installed too far apart/on opposite sides of the house).

I would like you to place a min-max thermometer in the furnace while the door is on for a while. if the inside of the cabinet stays above 32F, then freezing shouldn't be an issue. I would be surprised if the gas valve was dropping much below ambient temperature. there should only be airflow in the cabinet while the inducer fan is running, and it should basically go from the inlet pipe into the burner assembly.

Even if you have cold air feeding the furnace, the air sitting in the inlet pipe should be above outdoor temp as PVC isn't that good an insulator - so it should be warm until the furnace has been running.

I can't find any ice build up inside the pipe on the outside, and on the inside, as soon as I open the cabinet, I feel fresh air come in. BUT....this is also with the furnace working right now. So I'll have to check again when the furnace doesn't want to fire.

I placed the a thermometer at the bottom of the cabinet. I also lowered the thermostat quite a bit as I want the house to cool down, like we're away for a while, and I don't want the furnace to run. I'm off to work until midnight or later, and it's supposed to be frigid again tonight, so hopefully I'll catch it in the act again. My wife and daughter aren't home, so it's a good time to test this stuff out.

 

[66cj225]

The reason I'm discounting the gas supply issue, is that:

1) I don't see any ice up at the 2 regulators
2) I cracked open the union closest to the furnace, and I had gas flow
3) As long I draw warmer air from the basement, furnace will run tip top.

You wouldn't see anything with a stuck or iced up regulator; it's inside at the needle or the needle guide path. Only on a gage would it be visible. Broken diaphram would be odor out the vent hole.
Having 'gas flow' doesn't mean you have rated BTU (or metric equiv) input.
Inside air is better than freezing. Just trying to help.

How much is the dryer used? There isn't a lot of space there.

 

[bobbyjean]

Here are some pictures. Maybe someone with a sharp eye can spot something the installer and I are missing.

BTW. I asked the Installer to call Trane tech support. I wonder if I can call them myself as well? Or is it better to just let the installer do it, specially if it's a warranty issue they need to deal with.

did you try to take apart exhaust pipe at draft inducer? i found a small bird (baby) in one once...was also told a bat could make it's way down there...may be worth a try
how about a 2 inch street 90 at exhaust at termination-thinking wind gusts/pressure switch issue..either way need birdscreen when you get it fixed up

 

[KANSASBOY]

Found this same code .
https://vimeo.com/196672153
The problems seems to have been resolved. Sturm Heating come to the house the next morning and was here when the furnace woke up from night setback mode. Of course, the furnace did not exhibit the bad behavior you saw in the video. The burner fired on the first try. The Tech removed the burner assembly to have a look. THE ENTIRE BACK SIDE OF THE BURNER NOZZLES WERE COVERED WITH RUST! Did I mention?...this is a brand new furnace. The channels that direct the flame from the first nozzle to the other nozzles were also rusty. The Tech told me he cleaned up the rust as best he could using a wire brush. Since then the furnace has never failed to fire. You're guess is as good as mine as to why the downstream side of the flame nozzles on the burner were corroded so badly that the burner would not ignite. It pretty much has to be a QC issue at the factory.

 

[MUD DAWG]

Good find Kansasboy. Mine wasn't that bad, but it's the same sequence. Everything comes on as they should, but no fire.


Well fellas, I officially have no idea what to make of this. I'm here typing, so I didn't freeze to death. Believe it or not, the last 2 days the furnace hasn't missed a beat. The outdoor pipe has been connected this whole time, and it has been ****** cold. With the wind, we had - 40 temps for nearly 2 days.

Last thing I did on the furnace, was throw a thermometer in the cabinet, I also took out the power to gas valve to measure voltage. I turned off and on the gas valve switch. I also disconnected one other pressure switch to test it out. And that's it. But somehow (fingers crossed), it seems like the ghost has left the building.

However, the technician in me knows better, and says problems don't just disappear for no reason, but I'll stay optimistic. I'll call back the install company and talk to a different tech or manager and see if they've seen this issue with Trane furnaces. I'll call Trane directly on Monday as well, let's see if they'll tell me anything.

You know, for the comfort and safety of my wife and daughter, I shelled out more money to go with a quality brand furnace, and a respected installer, and I hope this all doesn't turn out to be a waste.

BTW, did you know - 40 is when Celsius and Fahrenheit meet? And rumour has it, with temps so cold, politicians for once, have their hands in their own pockets.

 

[crazy wheel]

Good find Kansasboy. Mine wasn't that bad, but it's the same sequence. Everything comes on as they should, but no fire.


Well fellas, I officially have no idea what to make of this. I'm here typing, so I didn't freeze to death. Believe it or not, the last 2 days the furnace hasn't missed a beat. The outdoor pipe has been connected this whole time, and it has been ****** cold. With the wind, we had - 40 temps for nearly 2 days.

Last thing I did on the furnace, was throw a thermometer in the cabinet, I also took out the power to gas valve to measure voltage. I turned off and on the gas valve switch. I also disconnected one other pressure switch to test it out. And that's it. But somehow (fingers crossed), it seems like the ghost has left the building.

However, the technician in me knows better, and says problems don't just disappear for no reason, but I'll stay optimistic. I'll call back the install company and talk to a different tech or manager and see if they've seen this issue with Trane furnaces. I'll call Trane directly on Monday as well, let's see if they'll tell me anything.

You know, for the comfort and safety of my wife and daughter, I shelled out more money to go with a quality brand furnace, and a respected installer, and I hope this all doesn't turn out to be a waste.

BTW, did you know - 40 is when Celsius and Fahrenheit meet? And rumour has it, with temps so cold, politicians for once, have their hands in their own pockets.

Go ahead and have the burners checked. I worked on one furnace that the combustion air pipe was dripping condensation down and onto the burner that is located at the Hot Surface Ignitor. Burner crossover was rusted enough that it kept the furnace from lighting

 

[jdieter]

Mud Dawg, read entire thread and your problem sounds exactly what I'm experiencing. Unfortunately I'm 1200 miles from my house spending the winter in Florida. I've got a Lacrosse temp monitor with one sensor detecting room temp and another dropped a few inches in register. About the time we hit the extreme cold and wind chill my new LPG furnace house and duct temps dropped dramatically. We supplement the furnace with a wood stove and thinking their fill calculation was skewed from no wood heat called for a fill in case we were empty. Gas man said we were at 40% and he saw condensate out the furnace exhaust. Up to the bitter cold snap the temp reading were consistent, and I could tell when the furnace was on gas or the heat pump by the duct temperature. The duct temp has been as low as 50dgf and high as 120dgf(only take a sample once an hour) during this erratic period. You've given me a wealth of data to consider when I get back to Indiana. I want to make sure I understand the final diagnosis a corroded burner assembly? If so I would have thought QC would have caught that at the factory. I would think the root cause would be some path for excessive moisture to reach the burner after the install. The weather is finally warming up north so It'll be interesting to see if my temp readings go back to a normal cycle of around 120-130 in the duct and 60-65 room temp.