RV Fact or Fiction? To keep RV windows from sweating, use an electric space heater instead of the RV propane furnace as propane heaters emit lots of moisture.
*Paraphrased/condensed from this source.
Fiction. RV propane furnaces do not add moisture to the interior of an RV.
It is true that a considerable amount of moisture (1.64 pounds of water per gallon of propane) is generated during the combustion of propane. However, since the combustion in an RV furnace takes place in a sealed combustion chamber vented to the outside, none of that moisture enters the interior of the RV.*
“At the root level, a forced air furnace draws in fresh air from outside the vehicle, mixes it with propane and burns it in a sealed combustion chamber.” Per the late Gary Bunzer, the RV Doctor.
The hot air you feel emitted from the heat ducts/registers is air that was drawn in from the interior of your RV, circulated around the exterior of the combustion chamber and pushed out through the heat ducts/registers. This is no different than the air being drawn into the back of a portable electric heater, heated by electric elements, and blown out the front.
Click here if you would like to learn more concerning propane heat and moisture problems in the interior of the RV like condensation forming on windows.
So why do many RVers believe that using an electric space heater rather than the propane furnace in their RV minimizes condensation?
Here are my observations
We have all experienced condensation forming quickly on the inside of single-pane RV windows after turning on the RV furnace on a cool, rainy day. However, if you turn on a portable electric heater instead of the RV furnace, the condensation doesn’t immediately form.
One kilowatt hour (kwh) of electricity is equal to 3,412 BTU/hour. Therefore a 1,500-watt (1.5 kwh) electric space heater, a favorite of RVers, will produce 5,118 BTUs in an hour (3,412 BTU/hour X 1.5 kwh = 5,118 BTUs). Compare that to a 30,000 BTU propane RV furnace operating around 70% efficiency.** In one hour that 30,000 BTU furnace will blow approximately 21,000 BTUs of heat into your RV. That is more than four times the amount of heat (BTUs) as the 1,500-watt electric space heater. Since condensation forms when warm, moist air comes in contact with a cold surface, like a window, it only stands to reason the faster the air is heated in your RV the faster the condensation appears. This leads people to believe in the myth that electric heaters are better than an RV gas furnace regarding controlling condensation.
*If your furnace is adding moisture to the interior of your RV, you have a compromised combustion chamber that needs to be repaired immediately. It is not only allowing moisture into the interior but potentially deadly carbon monoxide as well. Not to mention it is also a fire hazard as flames could escape the confines of the combustion chamber.
**RV propane furnaces are nowhere near as efficient as the newer gas furnaces found in most residences. Roughly 30 percent or more of the heat produced during the combustion process fails to be transferred through the combustion chamber into the interior of RV. The uncaptured heat is then exhausted outside through the exterior furnace vent of your RV.
Now, some questions for you:
- Is there a recurring half-truth you keep seeing online that you would like to see addressed?
- Were you taught something by other RVers that turned out to be bad advice?
- Have you recently read something that left you wondering, “Is that true?”
- Do you know something to be true, but none of your RVing friends believe you?
Please share your comments using the comment box below and we will do our best to provide the facts in a future entry.