Gas furnace not catching up to set point (on thermostat)

[Margaret]

Hi all,

Anyone have an idea why my gas furnace can’t catch up to set point (I.e. temperature set on thermostat)?  It blows out warm air, but struggles, and ultimately, the ambient temperature gets colder and colder.  
 

I should add that I had a distinct leak.  I smelled gas, and the furnace worked as long as I had gas in the tank, but after about four or five days, the furnace would sputter (and have trouble catching up), the stove would die, and I would have to refill my tanks.  I also got brand new tanks, just in case.
 

The RV repair guy claims to have fixed the leak (I will know in a few days) by replacing the hoses in the nose where the propane tanks are located, but now the furnace, though it blows warm air, is unable to catch up to thermostat.  It gets colder and colder inside.

I told the repair guy, and he said he would be back to fix it, but well, you know how that goes. He isn’t answering the phone or his texts.  I realize he is swamped with work orders, and his truck has mechanical issues, but that means I have to rely on space heaters that are expensive, and that also don’t adequately heat the space.

 

Thanks, Margaret 

[John E Davies]

Is there hot air coming out of the exhaust port? It should be too hot to hold your hand over it for more than a second or two.

Do your other propane appliances work OK now, after the repairs?

If they all are still screwed up, you still have a gas supply issue, it could be the regulator has failed, the pressure adjustment is wrong, a blockage (wasp nest in the air vent opening) , all sorts of possibilities. 

IF the others work right, there is a problem in the furnace itself. It is 40,000 btus, it should never struggle unless you have the windows open and it is crazy cold outside. How cold are the night temperatures?

Have you looked at the air ducts? Are they all attached properly, not torn, crushed, eaten by rodents?

Have you tried setting the thermostat to full hot? Does that change anything?

YOU need to go through some basic troubleshooting, to narrow down where the problem lies. Unfortunately the RV techs are swamped and have been for years. You may have to rely on electric heaters, if they are inadequate you need better ones. Open up cabinets and access hatches overnight. Good luck, this sucks….

I replaced my ancient box heater with this little heater, it works wonderfully well in place of the furnace. But I haven’t tried it below freezing yet.

Dreo Space Heaters for Indoor Use, Atom One Portable Heater with 70°Oscillation, 1500W PTC Electric Heater with Thermostat, Fast Safety Heat, Remote, 1-12h Timer, Upgraded Small Heater for Office Home

John Davies

Spokane WA

[Mike and Carol]

Hopefully, you don’t smell gas anymore.  I can’t add anything to what John suggests above.  I would be sure to check to make sure the ducting is connected and you aren’t just heating up in space between the hulls.  Mike

[Margaret]

19 hours ago, John E Davies said:

Is there hot air coming out of the exhaust port? It should be too hot to hold your hand over it for more than a second or two.

Do your other propane appliances work OK now, after the repairs?

If they all are still screwed up, you still have a gas supply issue, it could be the regulator has failed, the pressure adjustment is wrong, a blockage (wasp nest in the air vent opening) , all sorts of possibilities. 

IF the others work right, there is a problem in the furnace itself. It is 40,000 btus, it should never struggle unless you have the windows open and it is crazy cold outside. How cold are the night temperatures?

Have you looked at the air ducts? Are they all attached properly, not torn, crushed, eaten by rodents?

Have you tried setting the thermostat to full hot? Does that change anything?

YOU need to go through some basic troubleshooting, to narrow down where the problem lies. Unfortunately the RV techs are swamped and have been for years. You may have to rely on electric heaters, if they are inadequate you need better ones. Open up cabinets and access hatches overnight. Good luck, this sucks….

I replaced my ancient box heater with this little heater, it works wonderfully well in place of the furnace. But I haven’t tried it below freezing yet.

Dreo Space Heaters for Indoor Use, Atom One Portable Heater with 70°Oscillation, 1500W PTC Electric Heater with Thermostat, Fast Safety Heat, Remote, 1-12h Timer, Upgraded Small Heater for Office Home

John Davies

Spokane WA

Hi John!

Thank you for the reply.  I do believe there is hot air coming out of the exhaust, but I will check again in the morning, and see how hot it is.

My gas stove works, yes, but I'm not sure if the hot water is on gas or electric.  As for the fridge, I would have to kill the electricity to see if it reverts to gas.

Regulator, pressure adjustment, blockage from insects.  I will try to remember those.

40k BTUs is a lot, but yes, it is indeed cold.  It isn't that cold tonight, but temps have been in the 20s, and have gone as low as 26.  I think I tried using the heater when temps were in the 30s , and it still wasn't reaching set point.  I am confused, because I thought this was a four-season trailer?  When I had a single-hull Casita, it kept me warm down to zero F, and likely would have kept me warm at Sub-Zero temps.

I have looked at the ducts, and they seem fine, but I will examine them more carefully.  I have not tried full hot, but I have tried significantly higher temps, and the thing just struggled even more, and was unable to keep up.

Yes, it does kind of suck, bc honestly, I have had so many issues with this particular hull.  I have had leaking windows, a leaky hull, an A/C that malfunctioned, etc.

I was using a Lasko Ceramic heater; I am now using a Vornado.  But this will be expensive for me.  Electricity is not included here.  In addition, I'm not sure if electric heaters are as good at keeping the pipes from freezing?

 

Thank you, John

[Margaret]

18 hours ago, Mike and Carol said:

Hopefully, you don’t smell gas anymore.  I can’t add anything to what John suggests above.  I would be sure to check to make sure the ducting is connected and you aren’t just heating up in space between the hulls.  Mike

Hi Mike,

How do I check this?  I assume I look in the same compartment where plumbing is located?

 

Thank you!  

Margarwt

 

 

[Mike and Carol]

5 hours ago, Margaret said:

How do I check this?  I assume I look in the same compartment where plumbing is located?

Look under the curb side bed.  The silver ducting should be connected to the furnace and to the vents into the trailer.

[John E Davies]

Electricity for a space heater is a better choice than propane IF the outside temps aren’t too cold. That is why do many people use the heaters when plugged in. Yes, it doesn’t get under the floor, that is why you need to open up access hatches, pantry and closet doors, and the bathroom door, to let it circulate better. But pipes can freeze if the furnace isn’t working.

A 1500 watt heater is roughly 5000 btus. The furnace is 40,000. So that is why it must work properly in bitter cold temperatures IF you also want to keep water in the plumbing. Do you know how to winterize your Ollie?

FYI electricity in Spokane is $0.10 per kilowatt hour. So a 1500 watt heater costs $0.15 every hour that it runs. If it runs roughly 30% of the time, that is about $1.00 per day. You also have to figure in the cost of propane in your area, and whether the hassle of dragging two big tanks to get refilled is worth it. I personally find refilling to be an unrewarding use of my time and energy. Especially if I have to burn a lot of gasoline to get there.

John Davies

Spokane WA

[John E Davies]

What is your elevation where you are now?

John Davies

Spokane WA

[Margaret]

12 hours ago, Mike and Carol said:

Look under the curb side bed.  The silver ducting should be connected to the furnace and to the vents into the trailer.

Well, that doesn’t sound difficult.  I will do so, and report back!  Thanks, Mike!

[Margaret]

11 hours ago, John E Davies said:

What is your elevation where you are now?

John Davies

Spokane WA

Oh boy.  Aye, there’s the rub, or might be.  I am at 8,000 ft.  John.   I’ve heard that elevation can be a problem in an Oliver, Which doesn’t really make sense to me, because one of the primary things people do with campers is to go camping up in the mountains, with places like Colorado being a big draw, no? So why wouldn’t they make furnaces that could handle elevation? If it’s the propane, I purchased my tanks locally.

[Margaret]

On 10/25/2022 at 6:19 AM, Mike and Carol said:

Hopefully, you don’t smell gas anymore.  I can’t add anything to what John suggests above.  I would be sure to check to make sure the ducting is connected and you aren’t just heating up in space between the hulls.  Mike

No longer smelling gas.  

[Mike and Carol]

21 minutes ago, Margaret said:

Oh boy.  Aye, there’s the rub, or might be.  I am at 8,000 ft.  John.   I’ve heard that elevation can be a problem in an Oliver, Which doesn’t really make sense to me, because one of the primary things people do with campers is to go camping up in the mountains, with places like Colorado being a big draw, no? So why wouldn’t they make furnaces that could handle elevation? If it’s the propane, I purchased my tanks locally.

We dry camped at 9,100+ feet near RMNP this summer.  Furnace, stove top, hot water all worked fine.  So did the Weber and Blackstone.  I know some folks have had issues, it just doesn’t seem consistent.

[Margaret]

11 hours ago, John E Davies said:

Electricity for a space heater is a better choice than propane IF the outside temps aren’t too cold. That is why do many people use the heaters when plugged in. Yes, it doesn’t get under the floor, that is why you need to open up access hatches, pantry and closet doors, and the bathroom door, to let it circulate better. But pipes can freeze if the furnace isn’t working.

A 1500 watt heater is roughly 5000 btus. The furnace is 40,000. So that is why it must work properly in bitter cold temperatures IF you also want to keep water in the plumbing. Do you know how to winterize your Ollie?

FYI electricity in Spokane is $0.10 per kilowatt hour. So a 1500 watt heater costs $0.15 every hour that it runs. If it runs roughly 30% of the time, that is about $1.00 per day. You also have to figure in the cost of propane in your area, and whether the hassle of dragging two big tanks to get refilled is worth it. I personally find refilling to be an unrewarding use of my time and energy. Especially if I have to burn a lot of gasoline to get there.

John Davies

Spokane WA

Hi John,

 

Hi John,

 

So the temperatures are in the 30s and 40s during the day, but much colder at night. The nighttime temperatures can qualify as bitter cold. I am hoping that skirting the camper, which I have not yet done, might help. I could also put a very small, low wattage space heater underneath. My pipes haven’t frozen so far. The lowest temperatures have so far been in the mid- to low 20s at night.  However, as Winter proceeds, the temperatures at night can go as low as -10 or -15.  Last year, the lowest temperature was -20. I hope You Floridians don’t read this, because I know you’re going to have a heart attack, ha ha! Fortunately, I am used to subzero temps.

as far as winterizing, I purchased a heated water hose, wrapped a pipe cable around my sewer hose and insulated it, and I dump a little RV antifreeze into my black water and gray water tanks before I go to bed. My plan is to skirt the camper, and to place a very low wattage heater on a low setting underneath the skirting. Said heater will be propped up with bricks or what have you to prevent tipping over.   I could also use one of those chicken House lightbulbs.

 

Thank you , John

 

Margaret

 

I could also use one of those chicken house lightbulbs.

Thank you for the reminder to open up the kitchen drawers, the hatches, closets, and bathroom door.

 

Margaret

 

[Margaret]

2 minutes ago, Mike and Carol said:

We dry camped at 9,100+ feet near RMNP this summer.  Furnace, stove top, hot water all worked fine.  So did the Weber and Blackstone.  I know some folks have had issues, it just doesn’t seem consistent.

Hi Mike,

 

Hi Mike,

 

Doesn’t that depend on the individual furnace?

[Mike and Carol]

1 minute ago, Margaret said:

Doesn’t that depend on the individual furnace?

It would seem to me that if Oliver uses a Suburban furnace that they would all act about the same.  But, it doesn’t seem to be the case for some reason.  You may be right that it depends on the individual furnace.

[Trainman]

Not sure this would be your problem, but if you get a small bug blocking the jet on the furnace, or a bug nest in the jet tube back to the burner it can cause very erratic operation of the furnace, or any gas appliance. Usually if this happens your flame does tend to go out and it will try to restart. If and  when it burns it will have a popping sound outside at the furnace where you can hear it. This is probably not your problem, but it's just something to keep in mind when you have gas flow problems. This could also cause a gas smell as your unit is trying to relight and the gas flow is being interrupted.

trainman

[ScubaRx]

On 10/26/2022 at 8:48 PM, Mike and Carol said:

It would seem to me that if Oliver uses a Suburban furnace that they would all act about the same.  But, it doesn’t seem to be the case for some reason.  You may be right that it depends on the individual furnace.

We were boondocking deep in the red rock country south of Sedona several years ago with some other Oliver owners. The morning after the first night, I got up and hit the switch to turn on our Suburban water heater. It went through its regular startup, I heard the igniter clicking, then the whoosh of the burner lighting, it running for a maybe 15-20 seconds and then shutting down. It did this the obligatory 3 times before giving up and not trying again until I re-initiated the startup procedure.

Somewhere during all this, I heard our friend's water heater doing exactly the same thing. I went outside and found him pondering why both of them seemed to be having the exact same problem. We discussed this for a minute or two then remembered "something" that was done the night before. (This all happened several years ago and my memory fails me as to WHY this "something" was done...) But, my friend had licked the tip of his forefinger and wiped it across the gas orifice on both of our water heaters. Deciding that action was the only common denominator, each of us removed the orifice from our heaters and carefully ran a tiny copper wire through it. Nothing visible came out but after replacing the orifice's, each heater started right up and ran normally.

Admittedly, I did go around the world to say that it literally takes "nothing" to interrupt the proper flow of gas.

[Steve and MA]

On 10/24/2022 at 11:52 PM, Margaret said:

Hi all,

Anyone have an idea why my gas furnace can’t catch up to set point (I.e. temperature set on thermostat)?  It blows out warm air, but struggles, and ultimately, the ambient temperature gets colder and colder.  
 

I should add that I had a distinct leak.  I smelled gas, and the furnace worked as long as I had gas in the tank, but after about four or five days, the furnace would sputter (and have trouble catching up), the stove would die, and I would have to refill my tanks.  I also got brand new tanks, just in case.
 

The RV repair guy claims to have fixed the leak (I will know in a few days) by replacing the hoses in the nose where the propane tanks are located, but now the furnace, though it blows warm air, is unable to catch up to thermostat.  It gets colder and colder inside.

I told the repair guy, and he said he would be back to fix it, but well, you know how that goes. He isn’t answering the phone or his texts.  I realize he is swamped with work orders, and his truck has mechanical issues, but that means I have to rely on space heaters that are expensive, and that also don’t adequately heat the space.

 

Thanks, Margaret 

How cold was it outside?  When you replaced/refilled the propane tank was it completely empty?  Just a thought, but if the furnace performed adequately on a full tank but sputtered before it was empty, then it could be that the tank is losing pressure as the propane vaporizes.  Vaporization causes liquid propane to drop below ambient temperature.  The liquid propane temperature would fall more on a tank near empty than when full.  The colder the liquid propane, the lower its vapor pressure.  It could be that as a tank's liquid volume falls, the propane can't vaporize fast enough to keep up with the demand of the furnace.  

I'm not an engineer, so I could be misinterpreting the information on this web page. Propane Information – Flame Engineering It suggests to me that 10 lb of propane (a half-full 20 lb tank) would vaporize 38,000 btu of propane at 20° F.  That seems marginal for a 40,000 btu furnace.  

Real world experience:  Last February we went on a weekend trip in Junction TX.  Nighttime temperatures were in the mid 20's.  I only had the valve open on one of my 30 lb tanks. Around 3 or 4 AM it was getting cold in the trailer; the furnace had stopped running.  I switched tanks and was able to restart the furnace.  Later, when I had the tank refilled, it only took 26 lbs to fill it.  Either the rating is off, or there was still 4 lbs in the tank. It seems reasonable to me that the liquid in the tank had become too cold to vaporize, at least not fast enough to run the furnace.

We're planning to visit our daughter in Durango CO for Thanksgiving and expect to encounter nighttime temperatures in the 20s, or even teens.  We'll see how well the furnace does at 6500' in freezing temperatures.

Steve

[Mike and Carol]

2 hours ago, Steve and MA said:

We're planning to visit our daughter in Durango CO for Thanksgiving and expect to encounter nighttime temperatures in the 20s, or even teens.  We'll see how well the furnace does at 6500' in freezing temperatures.

Our son and family live in Durango.  We visited for a week in January two years ago.  Night time temperatures in the middle teens.  Furnace did fine.  We were not winterized and we had no freeze issues.  Mike