Should the furnace operate below 35 degrees

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EMan508

EMan508

Well-known member
Joined
Jan 2, 2012
Posts
146
Location
Lake Havasu City, AZ
I've been dry camping in some cold places lately.  My heatpump doesn't operate below 35 degrees which I think is normal. The odd thing is that my propane furnace works fine above 35 degrees and as soon as the temps go below 35 it blows cold air and goes into the lockout mode.  If I turn it off and back on again it usually will just go back into lockout mode.  I do not hear the flame ignite when the outside temp is below 35 degrees.

I suspect that the furnace needs to be cleaned and tuned. Is there a way to see/adjust the flame without pulling the entire furnace?  I see no access from outside/under the RV for the flame.

Has anyone here removed the furnace on a Winnebago Adventurer 35U? I have the manual and have performed all the steps to remove it but it doesn't want to budge.

I have applied electronic contact cleaner to the thermostat switches. No difference in its operation.

-Eric


Edit by John:  changed message icon to Topic Solved
 
Sounds to me like you have a gas flow problem.  Where was the tank last filled?  Down south it could be filled with Butane, which freezes about there.  Next time place a 60 watt light close enough to regulator to warm it up.  And see if you can get gas flow enough to light the furnace.
 
The only fill up I've had was in NY near Niagara Falls (Grand Island). I never heard of people selling butane as propane - another thing to look out for.

If the regulator is freezing up shouldn't the refrigerator also fail and beep that it has failed? Mine beeps (refrig) if AC is unavailable and the propane won't ignite.

-Eric
 
^^my guess as well (donn's response)^^

I would have a propane dealer check out your pressure, you could have a bad regulator.

EMan508 said:
If the regulator is freezing up shouldn't the refrigerator also fail and beep that it has failed? ..
Click to expand...

The furnace is going to use a whole bunch more gas than the fridge.
 
Make sure that your thermostat is set on the "gas" setting, not the "electric" setting.  Also, check your gauge on the tank. Sometime the panel doesn't give a true reading on how full the tank is.
Good Luck,
Indiana Journey
 
Even if the thermostat is set to electric, if the temperature differential is more than 6 degrees, the gas furnace should start. I would try it in the gas position though.
 
Your heat pump is acting normally in not being able to draw enough heat from the surrounding air at lower temperatures. Most consider the cutoff point in the thirties. These heat pumps are not like the home versions which can draw heat at much lower temperatures.

Your furnace should start automagically once the thermostat determines that the heat pump is no longer able to change the temperature by a certain amount after a certain time period. (More exact numbers and a better description are available in the thermostat manual available from RPC/Coleman).  It does not require the switch to be on gas at that point.  BUT.... if you determine that the magic number is approaching it might be a good idea to put the thermostat on gas and avoid any indecision between the heat pump and furnace.

Does the furnace start and just fail to light or not start at all??

By putting the thermostat on Gas  and raising the set temperature at least 5?, does the furnace start and heat?? If not then you have the usual suspects for a furnace not starting and working and the problem likely has nothing to do with the thermostat and heat pump interaction.
 
You aren't actually buying propane - instead it is LPG (Liquified Petroleum Gases) and there is no single formula for LPG gas. Southern gas suppliers blend in more butane than northern ones because warmer weather needs the higher vaporization temperature of butane for efficient use while colder weather requires less butane and more propane in the mix to work well below about 40 degrees. On the plus side, butane has more energy per gallon than propane, so you burn less LPG when it contains a high percentage of butane vs propane.

Northern gas suppliers may also blend in butane during the warm summer months, so it may be worth your while to top off your LP tanks with fresh propane LPG from a large supplier, so that you can be sure to get "winter blend" LPG.
 
It's possible that there may not be enough LPG in the tank to operate the furnace at the ambient temperature.
The vaporization rate of LPG changes with temperature, fill level of the tank and rate of consumption. It is possible to have enough in a tank at a given ambient temperature to operate a water heater or refrigerator and and not a furnace.
See HERE for some charts illustrating the effect.

I copied the following which may help explain it from a thread a few years ago:

"But there is one more factor: propane takes 760 BTU per gallon to evaporate. Using propane causes some of the propane to evaporate, chilling the cylinder and the remaining propane. Since the propane is colder than the environment, it begins to pull heat from the environment. The temperature will drop until the incoming heat matches the heat being used to boil the propane. Obviously the amount of the temperature drop depends on how fast the propane is being used. What may not be immediately obvious is that the amount of the temperature drop depends on how full the cylinder is, since the cylinder wall doesn't carry heat very well from the space above the liquid to the liquid. Ever notice the frost on a cylinder? It is only near the liquid level, and not above."
 
I had the same problem with mine and it was because my propane pipe to my furnace had a low point in it before it reached the furnace and there must have been a little moisture there that would freeze when the temp dropped. I put regular pipe insulation around that area of the pipe and I haven't had that problem again in the last 5 years.
 
I have the same exact problem...  My thermostat is on Electric Heat, then when the temp outside drops, I hear the gas furnace fire up, then shuts off and locks out.  I then will switch to Gas Heat, and the gas unit heats up. 

I also noticed that on really cold nights, I can turn the Gas Heat on, it will heat up and then never turn back on (guessing it locks out)..then by the time I notice, I get up, turn off the thermostat and back to Gas Heat and it stays on...

I've called RVP and they say that sometimes a propane tank can accumulate oil and this oil gets trapped in the rubber hose that comes out of the regulator, so they suggested to remove the line and see if oil comes out.  They said that the oil solidifies in the line and won't let propane pass through.

Has anyone tried this??
 
Good point about water in a propane line freezing. Could also be in the regulator. Since the flowing propane actually chills its surroundings, it would freeze before the ambient reaches 32.
 
Several years ago I had a gas furnace issue that would act like this, would not heat when temperatures dropped. The issue was the battery voltage dropped and the gas valve would not operate properly when it got cold enough. You might check your batteries and associated wiring.
Good Luck,
 
The fridge might not use enough gas to indicate flow, but the stove should.
Light all the burners on high and see what happens.
Also the quickest and safest way to heat up your regulator is hot water.
Pour hot water over the regulator and the tank and see if the furnace works.
Is your hot water heater working?  They also use lots of propane.
If you find that heat solves your problem, try to find a way to heat the tank compartment.

When my friends and I go up north sledding, we stay in a log cabin that has no heat or electricity.
When we use the BBQ or deep fryer outside we often put the 20lb tank in a large tub of warm water and cover it up.  If we don't, it is a constant battle to keep the flame going.  Mind you, this might be at 20 (or 30) below.
 
Sorry I didn't write back sooner but I had very poor internet at the Grand Canyon.

I'm in Lake Havasu City now (70 degrees) and the furnace fan turns on and the flame never fires up then locks up (I set the room temp to 80 for the test).  Eliminates the freezing pipe theory and butane problem.  I have turned on all three stove burners to high without a problem. It is getting worse as it used to work above 35 degrees.

I really think this 10 year furnace needs to be pulled out and cleaned/tuned.  This is the place to do it myself as I'm plugged in for winter now and the propane can be turned off (and not affect the frig).

Have any of you pulled and cleaned the furnace before?  I have the manual and that makes it sound very easy to pull out but I would like to hear from others if they have done it.

2003 Adventurer 35U
 
I've had a similar problem as the OP last year. When the temperature dropped below or near freezing the furnace just would not ignite. This only happened on one occasion. The next day the temperature rose and it worked again. Since that time I have used it in temperatures as low as 23? F with no problems. During the time that the furnace didn't work ... all the other propane appliance seemed to work fine.

I'm guessing that this is a problem inherent with living in the colder temperatures.

Below is a copy of the information from my manual that may help to explain the problem. Since this time I always tried to make sure the tank never goes below half during the cold weather.

Regulator Freeze-up

Regulator freeze-ups are caused by the presence of moisture in fuel. This moisture will pass through the cylinder valve and into the regulator where it can freeze. Fuel producers, tank and bottle manufacturers, and propane gas dealers take every precaution to reduce moisture, but sometimes only a fraction of an ounce entering the tank can cause problems. To help avoid the possibility of freeze-up, always keep tank control valve closed when not in use, even when tank is empty, to prevent moisture from collecting on the inside.
If regulator freeze-up should occur, you may attempt to thaw the regulator using a light bulb. DO NOT USE AN OPEN FLAME OR HEAT LAMP.
If moisture begins to cause problems, have your propane gas dealer inject a small amount of dry methyl alcohol in your tank (approximately one ounce to 20 pounds or one pint to 100 gallons) to help guard against regulator freeze- ups.

PROPANE VAPORIZATION IN COLD WEATHER

Propane gas vaporization increases and decreases in direct relation to ambient temperature. In other words, the lower the temperature, the slower the liquid propane will vaporize into a usable gas for appliances.
This means that in extremely cold weather when a large volume of gas is being used by the furnace for heating, it is possible to experience a loss of gas pressure.
At first, this problem may appear to be caused by an empty tank or a regulator freeze-up, but is actually caused by failure of the liquid gas to vaporize as fast as it is needed by the furnace.
The demand for propane to produce heat increases to the point where the gas cannot vaporize fast enough to keep the furnace going. The only solution to this problem is to reduce gas usage where possible.

Adjusting the temperature on the gas/electric refrigerator may be a first step. Using less hot water will also help, as well as refraining from using the gas cooktop. A final step is to lower the thermostat setting to reduce gas usage by the furnace.
 
While I had a friend visiting we pulled out the furnace and cleaned it the best we could without an air-compressor.  It really didn't seem very dirty but some sand did come out.  After we put it back together it seemed to work fine for a few weeks then it got down to freezing again and it would fail overnight. 

After it failed again I opened up the main access cover and ohm'd out the sail switch.  Sure enough that $9 switch was stuck in the closed position (internally, the lever would move freely externally and even make the click sound depressing the button). This is pretty much a sealed switch but I managed to get contact cleaner into it and my problem instantly went away.  I have since replaced the switch and I'm living the life of a king in warmth all night long now!

Thank you for all the help and suggestions!

Eric
 
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