Propane furnace freezing up

[MUD DAWG]

I'm curious if someone can help with this problem please.

A few months ago I had a brand new high efficiency Trane S9V2 installed, and the propane conversion kit was installed on it. I also had a propane tank installed on the property. The propane tank is a rental, and they gave me a 2 year old tank. No issues with the tank from what I can tell, but I'm wondering if it didn't have a bit of moisture in it?

For the past 3 weeks, we've been in a long and steady deep freeze, and my furnace doesn't want to fire. Before that, no issues at all. As it stands now, if the furnace goes off for even an hour, it won't come back when heat is called. I get no trouble codes on the board, I have no loose connections, no ice build up on the regulators, or any of the vent pipes.

The only way I can get the furnace going again, is to open it and use a hair dryer to warm it up a little. I run the dryer over the burners, and propane supply mostly. A few minutes later, it resets and fires away no problem. The heating company doesn't have an answer, but they're coming back to replace a pressure switch that seems to be sticking, but it might not be the issue. One way we've been getting by the last few days, is to disconnect the air intake, and just have the furnace draw air from the basement, but I know that's creating other issues and not a long term solution obviously.

Clearly something is freezing up and blocking the propane. But I'm surprised a brand new and high end furnace is experiencing this already and can't deal with it.

Any thoughts? I'm going through the manual now and see if I can dig something up, and deal with the issue once and for all.

Thanks

 

[naturalgas]

Sounds to me that your inducer motor is holding some moisture and is freezing/ binding up with the severe cold from intake. If your basement is large enough it won’t hurt taking intake air from basement until this severe cold snap passes.That would also affect your pressure switch. Heat tape intake if not enough free air space in basement. If your getting propane to unit I don’t think that is your problem.


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[MUD DAWG]

Sounds to me that your inducer motor is holding some moisture and is freezing/ binding up with the severe cold from intake. If your basement is large enough it won’t hurt taking intake air from basement until this severe cold snap passes.That would also affect your pressure switch. Heat tape intake if not enough free air space in basement. If your getting propane to unit I don’t think that is your problem.


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Thank you for the quick reply. You are correct about the propane likely not the cause, especially since I don't have any buildup on the regulators, and I cracked open the union at the furnace, and I definitely have propane flowing. I thought maybe a bit of moisture in the propane might freezup up the injectors?

The basement is about 1200 sqft, and the furnace is only a 60,000 BTUs, so you're probably right, and I should be OK with inside air.

About the inducer motor holding moisture, how do I check, and what I can be done about it? The condensate drain is flowing well. Maybe I can get it to freezup again, and I can use a small inspection camera to check through one of those plug holes in the motor?

 

[naturalgas]

If condensate is flowing and it’s a new unit I wouldn’t worry much. It has to be the crazy cold. You could also hang a 100 watt bulb inside cover that will warm it up enough till temps get back to normal.


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[MUD DAWG]

If condensate is flowing and it’s a new unit I wouldn’t worry much. It has to be the crazy cold. You could also hang a 100 watt bulb inside cover that will warm it up enough till temps get back to normal.


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Funny, I was thinking of ways to put some heat into the furnace. I thought maybe a hair dryer on a timer blowing into the air intake, but yeah the light bulb would work too.

I'm gonna spend some time and see if I can find any buildup, or see if the angle of the drain or something isn't right. And yes, it's been ****** cold. I'm happy we've finally defeated global warming

 

[Bluevista]

I had a propane furnace that would have explosions in the combustion chamber when it fired from delayed ignition, no heat guys could/wanted to figure it out. It blew out the pilot several times, knocked burners loose, didn't do it all the time, only when it got real cold outside and the basement got chilly.
I later learned from talking to an engineer at the heating and cooling supply one day that it was something about the propane not turning to gas efficiently in the cold . I don't know the physics but he hit it right on the nose.

If all else fails it's something to think about.

 

[SgtHawkUSMC]

Gas no likey the cold. That's for sure. Try to light a butane lighter in -20 deg temps. Won't happen.
How short is the fresh air intake run? Maybe try lengthening the run so the air has time to warm a little before it enters the furnace? I'd be pissed that the installer doesn't have a good answer...

 

[Bretny]

Lol thats funny having to hear up a furnace to get it working. O the joys of gas/oil heat.

 

[MUD DAWG]

Gas no likey the cold. That's for sure. Try to light a butane lighter in -20 deg temps. Won't happen.
How short is the fresh air intake run? Maybe try lengthening the run so the air has time to warm a little before it enters the furnace? I'd be pissed that the installer doesn't have a good answer...

The intake and exhaust pipes seem to be within spec for lengths. But I might have to check and make sure the exhaust has enough of a pitch to drain back into the furnace.

The installer seems a little stumped at the moment, but I'm giving them the benefit of the doubt as there are a few variables. So far they're willing and helpful in trying to get to the bottom of it.

Lol thats funny having to hear up a furnace to get it working. O the joys of gas/oil heat.

Yup, it's like washing dishes before putting it in the dishwasher

I just converted from oil. I never had an issue, but I have heard of oil lines gelling up. My old tank had a little electric heater element in case.

 

[finn]

On one of mine the drain tube was pushed in too far, so in cold weather the inducer fan would dip into condensate that accumulated at the bottom of the housing, slowing the fan and tripping the pressure switch.

Pulled the drain tube out a half inch and has worked fine ever since.

By the way, some of the local installers won’t put in an outside air supply because of problems with fine, wind driven lake effect snow fouling the inlet piping. They would rather plumb basement air than make a no heat service call.

I have personal experience with a coarse hardware cloth screen plugging in bad weather.

 

[gungatim]

you sure your gas valve isn't sticking?

when it calls for heat, and you get the heating element to glow, do you hear the valve click and still get no gas flowing to light? it should do that 3 times before shut down.

if that happens you will get a code.

just follow the process, the fan first runs to clear the vents, then inducer motor runs, pressure sensor reads good, then you get ignition, flame sense, etc. any problem will throw the codes.

it's possible the propane conversion wasn't done accurately when the pressure was set, they may need to come back out and re-do it.

 

[braxton]

just a thought as you say problem only started when temperature got low, maybe your propane tank isnt large enough. i say this because propane has to vaporize off pool in top of tank. a horizontal tank maybe better here because it has more surface area to vaporize fuel enclosed is a link to onan t-o15 gaseous fuel manual that can explain this better than i ever could hope this helps

 

[MUD DAWG]

you sure your gas valve isn't sticking?

when it calls for heat, and you get the heating element to glow, do you hear the valve click and still get no gas flowing to light? it should do that 3 times before shut down.

if that happens you will get a code.

just follow the process, the fan first runs to clear the vents, then inducer motor runs, pressure sensor reads good, then you get ignition, flame sense, etc. any problem will throw the codes.

it's possible the propane conversion wasn't done accurately when the pressure was set, they may need to come back out and re-do it.

When heat is called, the fan will turn on and run freely, then the igniter will light, and nothing happens. I don't hear a click. What would cause the gas valve to stick?

After trying for 3 times, the board will show error code 2.1, which is the lockout after 3 tries. No other error codes ever come up.

I could have them check the propane conversion again. I know the installer measured the pressure for Heat 1 and Heat 2, and they were within spec. And seeing how it works correctly during warmer weathers, do you still think there could be an issue with the conversion?

Another question. Is it possible the propane supply pressure isn't high enough?

 

[MUD DAWG]

just a thought as you say problem only started when temperature got low, maybe your propane tank isnt large enough. i say this because propane has to vaporize off pool in top of tank. a horizontal tank maybe better here because it has more surface area to vaporize fuel enclosed is a link to onan t-o15 gaseous fuel manual that can explain this better than i ever could hope this helps

I have a 500 gallon torpedo tank, and the regulators are sized correctly, so unfortunately I don't think that's the problem.

 

[braxton]

do you have frost or ice around regulator at tank or on line? another thought could you take line loose and connect it to 1 or 2 burner tank top heater? that will check for sure if it is supply or furnace problem

 

[braxton]

my bad was typing while you posted your reply, sorry just trying to help

 

[theoldwizard1]

Gas no likey the cold. That's for sure. Try to light a butane lighter in -20 deg temps. Won't happen.

Butane is not propane ! Butane will not vaporize below about 30F. Propane is good down to like -40F, but the pressure from the tank does drop a lot.

What most home get delivered in summer is a mixture of propane and butane. If you have not had a delivery in 6 months, what is in the tank probably contains some butane.

My gut says this is NOT a gas issue. A special gauge is required to chek to pressure at the gas valve.

When the thermostat calls for heat, does the draft inducer fan kick on ? If NOT, then the control board is not getting the signal or as stated previously there is a problem with the inducer motor or the wiring going to it.

 

[gungatim]

When heat is called, the fan will turn on and run freely, then the igniter will light, and nothing happens. I don't hear a click. What would cause the gas valve to stick?

After trying for 3 times, the board will show error code 2.1, which is the lockout after 3 tries. No other error codes ever come up.

I could have them check the propane conversion again. I know the installer measured the pressure for Heat 1 and Heat 2, and they were within spec. And seeing how it works correctly during warmer weathers, do you still think there could be an issue with the conversion?

Another question. Is it possible the propane supply pressure isn't high enough?

check if you are getting 24v to the valve solenoid when the igniter glows. there is usually a separate fuse on the board for the gas valve but if blown it should set a code. you could have some moisture in the line freezing up in the valve, or just a weak valve. try tapping on it when it attempts to fire.

do be careful, obviously your working with the panel open around gas and electricity, if not comfortable call a pro. (though I've had professional's work on mine who didn't have a clue, putting wrong pressure valves on, disconnecting hoses, etc. and still not fixing it, which is why I learned to fix my own furnace from now on).

 

[theoldwizard1]

When heat is called, the fan will turn on and run freely, then the igniter will light, and nothing happens. I don't hear a click. What would cause the gas valve to stick?

On most gas appliances, the gas valves come in pairs. It does sound like one is sticking. **** HAPPENS.

You can check the resistance of each solenoid (ohms) but they are usually replaced in pairs.

 

[MUD DAWG]

When the thermostat calls for heat, does the draft inducer fan kick on ? If NOT, then the control board is not getting the signal or as stated previously there is a problem with the inducer motor or the wiring going to it.

Yeah the fan kicks on like it should, and continues to run for a while after the igniter goes out. I also don't hear a gurgling sound, so that kind of eliminates major water puddling.

check if you are getting 24v to the valve solenoid when the igniter glows. there is usually a separate fuse on the board for the gas valve but if blown it should set a code. you could have some moisture in the line freezing up in the valve, or just a weak valve. try tapping on it when it attempts to fire.

I don't think it's a blown fuse, as it shouldn't fire when warmer. Initially I thought it was a stuck pressure switch, so I disconnected the pressure switch, blew into it, and when it was trying to fire, I tapped it a few times, but that didn't do the trick.

The hair dryer heat, is absolutely the solution (along with not drying outside air). So that totally leads me to believe something is freezing up.

 

[MUD DAWG]

On most gas appliances, the gas valves come in pairs. It does sound like one is sticking. **** HAPPENS.

You can check the resistance of each solenoid (ohms) but they are usually replaced in pairs.

Yeah I'll check it out. Thanks.

And to the point of safety concerns raised by Gungatim. It's always good to repeat it, and bare in mind. I'm a refrigeration tech, so furnaces aren't my field, but still know the dos and don'ts.

The furnace is still under warranty, and hopefully the installers will get it all done, but it doesn't hurt for me to try to diagnose and give them as much info as possible, and for me to get to know the machine so I'm not stuck in the middle of a freezing night.

 

[1953mercury]

Do you have a damper on your outside air inlet? If not that may be causing your freeze up issue. Mike

 

[MUD DAWG]

Do you have a damper on your outside air inlet? If not that may be causing your freeze up issue. Mike

Are they supposed to have a damper? I'm pretty sure they don't even want screens on them anymore.

 

[SgtHawkUSMC]

Butane is not propane ! Butane will not vaporize below about 30F. Propane is good down to like -40F, but the pressure from the tank does drop a lot.

What most home get delivered in summer is a mixture of propane and butane. If you have not had a delivery in 6 months, what is in the tank probably contains some butane.

Thanks! I didn't know butane wasn't propane! Sorry for the exclamation points. I thought we were yelling...
My point was that it's a gas. I didn't know they mixed butane in with propane, but that actual helps my point. It was just a thought for something to think about. Several people have mentioned that it could be the crazy cold causing this. I suggested lengthening the intake pipe to warm the air a little before getting to the fire box.
I'm glad to hear the installer isn't being a tool about it. That would be pretty sad if they were. I'm sure he'll get it sorted out. Good luck.

 

[TTTTTT]

Went down to -33C. A few nights ago. No issues with our propane forced air. Our fresh air intake is not from outside though from right off the furnace located in the basement. Possibly the air being drawn in from outside side is too cold causing a temporary freeze up. I know generally this shouldn't be an issue.

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[TTTTTT]

Went down to -33C. A few nights ago. No issues with our propane forced air. Our fresh air intake is not from outside though from right off the furnace located in the basement. Possibly the air being drawn in from outside side is too cold causing a temporary freeze up. I know generally this shouldn't be an issue.

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

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[Dagny]

how cold is your basement? don't put lights or blow dryers. It sounds like your furnace man will get it.

The furnaces I sell have a small pressure switch on the lp gas line that shuts the furnace down when the gas pressure gets to low. Could you post a picture?

 

[MUD DAWG]

how cold is your basement? don't put lights or blow dryers. It sounds like your furnace man will get it.

The furnaces I sell have a small pressure switch on the lp gas line that shuts the furnace down when the gas pressure gets to low. Could you post a picture?

A picture of the furnace or pressure switches? I know they're Honeywell switches, I believe 2 are 40 WC, and the 1 in question is 20 WC.

The basement is a little colder than upstairs as we don't use it. The furnace room is pretty big and the furnace has lots of room around it. I also have the dehumidifier running down there.

I've heard some HVAC installers prefers indoors air as much as possible, but in my case, I know that creates a negative vacuum, which will put pressure on every nook and cranny, and it'll draw more cold air into the basement. If the furnace was located in a less air tight place, then I can see the advantage of using warmer air.

 

[MUD DAWG]

A little update.

I hooked up to outside air again, and let the furnace sit for a couple of hours before calling for heat. Sure enough it froze again. This time I listened around, and the gas valve definitely didn't click. I used the hair dryer and reset the board. A couple of minutes later I heard a definitive click from the gas valve and it fired.

So question is what's causing the valve to stick? I'll recreate this for the installer when he returns. I'm happy to hopefully have narrowed this down further.

 

[u3b3rg33k]

A little update.

I hooked up to outside air again, and let the furnace sit for a couple of hours before calling for heat. Sure enough it froze again. This time I listened around, and the gas valve definitely didn't click. I used the hair dryer and reset the board. A couple of minutes later I heard a definitive click from the gas valve and it fired.

So question is what's causing the valve to stick? I'll recreate this for the installer when he returns. I'm happy to hopefully have narrowed this down further.

Seems to me the residual heat from the last call should be more than adequate to keep the furnace warm enough. is your gas valve at or below 32F inside your furnace? that would seem to be an issue.

It's quite possible for something to be sticking and not be literally frozen. heating with a hair dryer will cause thermal expansion - quite possibly un-sticking it.

 

[MUD DAWG]

Seems to me the residual heat from the last call should be more than adequate to keep the furnace warm enough. is your gas valve at or below 32F inside your furnace? that would seem to be an issue.

It's quite possible for something to be sticking and not be literally frozen. heating with a hair dryer will cause thermal expansion - quite possibly un-sticking it.

I don't know for sure, but I'd say the gas valve is very likely below 32. It's very close to the outside air pipe. And this issue only happens with outside air drawn in. Basment air will let it run without missing a beat. And about a month ago, before this deep freeze, outside air was fine as well.

 

[naturalgas]

Something is in intake blocking air flow or it’s undersized or to long. Each 90 degree elbow equals 7 feet


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[MUD DAWG]

Something is in intake blocking air flow or it’s undersized or to long. Each 90 degree elbow equals 7 feet


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How would a restricted air flow freeze the gas valve? And what confuses me is that why it worked well on the warmer days.

 

[u3b3rg33k]

I don't know for sure, but I'd say the gas valve is very likely below 32. It's very close to the outside air pipe. And this issue only happens with outside air drawn in. Basment air will let it run without missing a beat. And about a month ago, before this deep freeze, outside air was fine as well.

can you throw a min/max thermometer in the cabinet? and your valve shouldn't be freezing assuming you have dry propane... assuming.

also, which inlet position did you choose for the intake air? perhaps relocating the entry point into the furnace cabinet is an option? if the inlet air dumps directly on the valve and you can make it not dump directly on the valve.

it would seem to me that residual heat would leave the cabinet warm and heat the valve up, but I currently have an 80% unit so mine has so much waste heat it's laughable.

 

[MUD DAWG]

can you throw a min/max thermometer in the cabinet? and your valve shouldn't be freezing assuming you have dry propane... assuming.

also, which inlet position did you choose for the intake air? perhaps relocating the entry point into the furnace cabinet is an option? if the inlet air dumps directly on the valve and you can make it not dump directly on the valve.

it would seem to me that residual heat would leave the cabinet warm and heat the valve up, but I currently have an 80% unit so mine has so much waste heat it's laughable.

I could ask the installer about relocating the inlet. As you can see from the picture, it dumps the air right on top of the burners, and all the metal is connected to the valve. But then again, it's a very air tight cabinet, so the entire cabinet will get cold equally. I can see a benefit to relocating the inlet if moisture drops were an issue, but I think cold air alone, it won't matter.

The inlet is 12 feet of piping, 3 - 45 degree elbows, and 1 - 90 outside the house. It seems reasonable to me, and they definitely took the shortest route possible. I'll double check the install manual for maximum lengths.

Maybe there's a little bit of moisture in the propane, and maybe next year it'll go away, but I still want to be sure of it now. I'll have the installer check the gas valve. I didn't want to get into it, until he comes back. At least I'm lucky and the issue is inside the house and I don't have to keep going out to warm up the regulators or valves outside.

 

[u3b3rg33k]

With that setup "all" of the air will be flowing straight from the pipe into the burners when it's running - it shouldn't be flowing over the gas valve to get there. probably not point to relocating the inlet. I would think the gas valve would see heat from the firewall, but maybe not? got a contact temp gauge you can play with in there?

 

[naturalgas]

How would a restricted air flow freeze the gas valve? And what confuses me is that why it worked well on the warmer days.

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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[MUD DAWG]

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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Service guy just left. He replaced that one pressure switch that seemed a little sticky, so fingers crossed.

What do you think it is about the intake piping that could be causing an issue. The run is relatively short with few restrictions.

 

[naturalgas]

Ok so maybe a bad brand new pressure switch. Strong winds,storms can affect the intake piping. The installation manual that came with unit will tell you the guidelines for piping. If it fails again a volt meter will tell you if the gas valve is getting 24volts or not. Hopefully it was just the PS.


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[MUD DAWG]

Ok so maybe a bad brand new pressure switch. Strong winds,storms can affect the intake piping. The installation manual that came with unit will tell you the guidelines for piping. If it fails again a volt meter will tell you if the gas valve is getting 24volts or not. Hopefully it was just the PS.


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I'll check the voltage next time it happens. Thanks.