Furnace Failure

Jaytalk · 12-23-2018, 04:01 PM

Recently went camping up in the mountains above 7000 feet. For some reason, the furnace heater would not start and consistently stay on. It must’ve been in the low 30s at night. Luckily was plugged into shore power and had a little space heater. So, I could not really test how well the heat was held in the rig using the propane furnace. It was pretty chilly, but we survive the night. Interestingly the furnace started working normally again once we got out of the mountains. I did turn on the tank heaters, and had no problem with the plumbing. I think we would’ve been fine if the furnace heater has been working. We have a Greyhawk 29 MVP. Anyone have any ideas as to why this happened?

**norty1** · 12-23-2018, 06:07 PM

Look up the specs on the heater and the resulting problems with using propane at altitudes.

Jaytalk · 12-26-2018, 01:14 AM

Quote:

Originally Posted by norty1

Look up the specs on the heater and the resulting problems with using propane at altitudes.

Are you aware of any problems that you can speak about?

**norty1** · 12-26-2018, 07:56 AM

Quote:

Originally Posted by Jaytalk

Are you aware of any problems that you can speak about?

When propane burns, it is mixed with ambient air. At high altitudes the ambient air contains less oxygen. This causes changes in the efficiency of the appliance using propane. Some say it does not affect them while others have problems.

Google propane at high altitudes and you will get an ear full.

Jaytalk · 12-26-2018, 11:47 PM

Thanks for the response. I certainly invite others to comment as well.

o2silverado · 12-27-2018, 09:05 AM

Combustion appliances need to be set for the altitude that they will operate in. Generally they are factory set for sea level to 3500 to be trouble free. Once you start to climb above 3500 the air gets thinner and thinner. Less oxygen means a lean air to fuel mixture and a poor flame = issues with a flame sensor keeping a furnace lit. If you are consistently camping at this altitude I suggest setting your furnace up for this.

2edgesword · 12-27-2018, 09:17 AM

Here is an article that discusses the issue in general:

https://www.achrnews.com/articles/13...e-applications

Jaytalk · 12-27-2018, 07:42 PM

Quote:

Originally Posted by o2silverado

Combustion appliances need to be set for the altitude that they will operate in. Generally they are factory set for sea level to 3500 to be trouble free. Once you start to climb above 3500 the air gets thinner and thinner. Less oxygen means a lean air to fuel mixture and a poor flame = issues with a flame sensor keeping a furnace lit. If you are consistently camping at this altitude I suggest setting your furnace up for this.

Thanks for the advice, but I’m not sure how to adjust the furnace for a high altitude usage. Do you know how that’s done?

o2silverado · 12-27-2018, 09:23 PM

To obtain a clean burn at that altitude your going to need a orphice change in the furnace. I do not have access to that info personally. I would give the furnace manufacturer a call and they should be able to get you the proper orphice size. It really isn't a fix that can be done on the fly. Once the correct orphice is in place you will need to fine tune the air/fuel ratio at elevation.

cabinetmaker · 12-27-2018, 10:03 PM

Hi Jaytalk! Sorry to hear of your furnace problem. I don't think it is the altitude. We have the same motorhome and same furnace as you and we were at 9000 feet this past summer and ours worked fine.

We have had many trailers and motorhomes over the years and never had any problems at high altitude. The furnaces are made to work in all kinds of places...maybe not as efficient but it will work.

I believe your problem might be a supply problem. If the propane regulator is not set correctly or working properly it can cause this problem. Works great at low altitude but not at high altitude. Some regulators are adjustable. You will need to have a flow meter test done to be sure you have the proper gas flow. It needs to be around 11 water column inches which is right flow for your RV appliances.

Propane with too much moisture can also cause this. Where did you buy propane last? Some RV parks sell propane but be careful because they might not sell much and it sits around and goes bad.

If your furnace works at sea level but not high altitude then I would doubt the furnace is the problem. I would suspect the supply. How did the hot water heater do at altitude? Refrigerator? Stove? Could be these appliances are not as sensitive to flow as the furnace. Anyway, before tearing into the furnace I would look at this. Regulators go bad but luckily are easy and cheap to change.

Jaytalk · 12-27-2018, 11:19 PM

Quote:

Originally Posted by cabinetmaker

Hi Jaytalk! Sorry to hear of your furnace problem. I don't think it is the altitude. We have the same motorhome and same furnace as you and we were at 9000 feet this past summer and ours worked fine.

We have had many trailers and motorhomes over the years and never had any problems at high altitude. The furnaces are made to work in all kinds of places...maybe not as efficient but it will work.

I believe your problem might be a supply problem. If the propane regulator is not set correctly or working properly it can cause this problem. Works great at low altitude but not at high altitude. Some regulators are adjustable. You will need to have a flow meter test done to be sure you have the proper gas flow. It needs to be around 11 water column inches which is right flow for your RV appliances.

Propane with too much moisture can also cause this. Where did you buy propane last? Some RV parks sell propane but be careful because they might not sell much and it sets around and goes bad.

If your furnace works at sea level but not high altitude then I would doubt the furnace is the problem. I would suspect the supply. How did the hot water heater do at altitude? Refrigerator? Stove? Could be these appliances are not as sensitive to flow as the furnace. Anyway, before tearing into the furnace I would look at this. Regulators go bad but luckily are easy and cheap to change.

Cabinetmaker, thanks for your reply! I was wondering when you were going to come on in and comment.

I’ll check into the regulator problem as a possible solution. I was really surprised because, I thought the furnace would work at any altitude as well. The refrigerator and the stove worked fine. We were hooked up to electricity so I never used the gas water heater. Again, thanks for your comments.

**norty1** · 12-28-2018, 08:08 AM

A flow problem makes sense. I would think that the furnace which is likely the largest consumer of LP after the hw heater would be most likely to show a flow problem. That would be a good place to start. I'm not sure how the altitude would restrict that but I'm no expert.

I know in gas generators that the fuel/air mixture is affected by altitude and can affect the output.

jd99336 · 12-28-2018, 11:03 AM

I had a similar problem in my 2016 Greyhawk while in Bryce Canyon a couple of years ago. Could not get service until I got home. The dealer had a lot of different thoughts and "fixes" but I had experienced problems with poorly aligned thermo-couples over the years in other RV's and that is what it felt like to me. Even with the newer start systems (spark versus pilot flame) there is a thermo couple placed over a small flame port that tells the system there is fire present which opens the main gas valve. If the thermo couple is not reaching sufficient temps to generate the small current to the valve, the system will go through the start, but then shut down in order to prevent unburned propane accidents (either gassing you in your sleep or building up and exploding). It is the same on a gas hot water heater in your home and likely on a home gas furnace.

Symptom - Furnace would start, but shut down after a few seconds. It would repeat the cycle over and over. During the warmer part of the day (40-50 degrees) it would eventually come on and stay, but then repeat the process at the next cycle. In the colder temps, it would never reach the "stay on" mode. Like you, I had a space heater and was on shore power.

The dealer fired it up on a nice 60-70 degree day and let it run at max temp for a couple of hours and said, "cannot duplicate". I told them I was pretty sure it was the thermo-couple (some argued circuit board), so after it cooled down for a couple of hours, I took them out and it would not start again until 4 or 5 attempts. The tech re-aligned the thermocouple and it has ran fine ever since.

I was not able to see where the thermo couple is in my unit, so can't advise you how to fix it, but I have operated my furnace up to 8,000 feet without an issue, so you may want to have that checked if your symptoms are similar.

JudyB · 01-02-2019, 02:14 PM

X2 on that. Had same with our Redhawk at 8000ft and above....dealer fixed it via thermo coupler and no problems since. These are made in ID and set for lower altitudes. Dealer can fix. Just tell him problems with high altitudes.

MikeeDee1 · 01-02-2019, 02:42 PM

Ther is a sensor, that has killed the gas in one of my Rvs. I couldn’t get heat or hot water. I think I had to ventilate my camper for it to reset. Just a thought and from experience.

Thanks,

Mike

Tinkman · 01-02-2019, 05:57 PM

I've had this same problem with my water heater. I've found that if I open the access door to increase ventilation it seems to help.

o2silverado · 01-02-2019, 06:11 PM

Quote:

Originally Posted by Tinkman

I've had this same problem with my water heater. I've found that if I open the access door to increase ventilation it seems to help.

Have you tried to adjust the air mixture on the burner tube. People should not assume that these appliances are always set up properly. These are things that can lead to catastrophic failures if left untreated.

EagleOne · 01-03-2019, 03:50 PM

We also camp at altitude (Colorado) and have not had an issue with the air mixture. We did however have a problem that looked like a thermostat issue (neither the heater, fan or the AC would turn on. After a three week wait to get the rig in the shop and a three week wait to have the rig looked at, the problem was a loose ground on the furnace. Once this was corrected, all of the systems worked fine.

baehrelw · 01-05-2019, 06:58 PM

We had the same problem. We were traveling with 2 other couples both with Jayco and they did not have the problem. We contacted our dealer in Michigan and they never heard of the issue. We contacted a local rv and they were not cooperative. We contacted the furnace mfg and they advised that the unit has a altitude limit of 6000ft. We messed around and adjusted the igniter closer to the gas and the problem was resolved.

Sunflake · 01-07-2019, 08:10 PM

I’ve been doing HVAC for a living for 16 years. The propane tank heaters are a good idea because as you use propane or have a pressure drop in the tanks. Which is why they get cold when being used. My guess is they need the correct orifices for high altitude. High altitude equals less air making it very hard for correct combustion. Without the proper air/fuel ratio the burners in your furnace won’t stay lit. Make sure the propane pressure to the furnace is at 11”wc. After that it’s air and an igniter.

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