Review of modern RV Heating Systems for those willing to extend the RV-in season beyond the short summer time or exploring colder climate zones….
For many of us, RV-ing is associated with summer activities, so eventually one of our major concerns is cooling.
However, given the fact that these days RV-ing became the “Life Style” rather than short summer vacation adventure, the subject of heating also starts to be an important issue.
Let’s make it clear from the beginning – the right RV heating system depends on how, where and when you would like to enjoy your vacations. I guess the following assumptions are valid for majority of RV-ers:
These greatly simplify heating solutions because the mentioned above conditions imply ambient temperatures above the freezing level. In other words the adequate heating system should be ready to alleviate the impact of chilly weather conditions (let’s say down to low 40’s). As we all know, humid cold weather will have serious impact on our level of comfort and enjoyment when on the road.
The beauty of the extended RV-in season: from the Spring till late Autumn...
Obviously if these are our goals, we do not need a 4-season RV with full thermal insulation, enclosed and heated underbelly and water tanks. To make it clear - there is nothing wrong with having good thermal insulation. In fact all-seasons RV will definitely improve not only heating but also cooling efficiency and so lower the daily cost. It can also save us from headaches when unexpected early Spring or late Fall freezing takes us (and RV’s water tanks and pipes) by surprise. However, it all comes at the higher initial cost and has to be economically justified. The bottom line is – the 4-season RVs are more expensive, so you may never recover the extra cost if not planning winter RV-ing.
Heating Systems for chilly weather conditions
Example of the Heat Strip (Dometic)
Heat Strips are small resistance coils converting electrical energy into heat (these are probably the most familiar to us heating elements). They are placed in front of the fan blower in the AC unit so basically they have nothing to do with the AC itself. They just make use of AC ‘s fan and hot air distribution system (either ducts or distribution box).
The Heat Strips have many advantages but their help in “fighting” cold weather is very limited.
But the cons are also numerous:
Bottom line: They are inexpensive, easy to install (provided you already have an AC in your RV), safe, but can make change only in ambient temperatures above 50’s (depending on installed power and size of your RV).
Dometic rooftop AC/Heat-Pump unit (Cooling 15k BTU/Heating 9.6k BTU)
Heat pump makes an integral part of an Air Conditioner, so it cannot be considered as an “add-on” to the existing AC unit. In simple words the Heat Pump is the AC itself but working in reverse direction. The cooling operation consists in evacuating heat (and moisture) from the climate controlled area and dumping it outside in the air. The heating operation transfers the heat in the opposite direction (evacuates the heat from the outside and releases it inside of the climate-controlled zone).
It’s obvious but let’s highlight the facts:
The AC unit can more or less effectively suck the heat from the warm area and bring its temperature down (provided the area is small enough for a given AC cooling power). To do so, the AC must dump the evacuated heat into the outside air. However if the outside temperature hits triple digits (what can quickly happen when roof-mounted AC’s heat-exchange coil is exposed to summer’s sun) the heat dumping process becomes very inefficient if not impossible. As the result, the cooling process stops (in fact, the AC components may be damaged)
And the opposite is also true - the Heat Pump can increase the interior temperature in the small controlled area by dumping the heat captured outside. But there is a limitation here – when the outside temperature is low (let’s say lower than 40 degF), there is no much “heat” accumulated in the outside air and the process of “harvesting” it becomes energy inefficient. In other words the electrical energy used to reverse the direction of the heat flow (outside-in) will be higher than the amount of energy contained in the transferred heat. The bottom line is – in such conditions the traditional resistance-based electrical heater will be more efficient and less costly to operate. Note that similarly as in the cooling mode, the heat-pump may be damaged if operated in temperatures outside of the specified range.
Because the heat-pump exchanger will never get red-hot, it can be rated at higher powers compared to Heat-Strips without the risk of damaging remaining parts of the AC module. That’s why heat-pumps can act as traditional heaters, warming up RV’s interior to comfortable temperatures (well, under condition that the exterior temperature is higher than low 40’s (check specs for a specific unit).
Most AC units are roof-mounted so they do not take any interior storage space (compared to “under-bench” units). But there is also an extra benefit - ceiling placement is optimal from the point of view of the cooling process. The cold air is heavier than the warm one so it naturally drifts down giving place to the warm air. This natural “convection” induced air mixing process contributes to uniformity of the interior temperature.
However, the rooftop location of the heating unit is not optimal. The warm air naturally accumulates near the ceiling while colder one near the floor. That results in let’s call it “vertical” temperature gradient and “hurts” where it pains the most (feet level).
Well, there is no paradise, by the same mechanism, floor-level under bench AC units are far from optimal when it comes to cooling, but very good when it comes to heating.
Of course, the ducted systems and the blowers can change the picture by mixing air at the inconvenience of extra noise from fans and “windy” environment.
Summarizing: The AC/Heat-Pump module is an elegant, practical and good-enough heating solution when grid or generator is available. While you cannot use it in freezing temperatures, it will certainly guarantee comfortable living in chilly weather (more-or-less from Spring till Fall).
These traditional combustion /forced-air furnaces are most common sources of heat in RVs. In many aspects they look and operate like “miniature” versions of familiar gas /forced-air residential furnaces. Thanks to the DSI device (Direct Spark Ignition) they are running fully automatically controlled by wall thermostat. Similarly as their bigger residential cousins, they need electricity for control electronics and blowers. The safety mechanism includes several sensors and propane valve that can cut-off gas supply when needed or necessary.
Dometic 35k BTU Propane Furnace is a compact, lightweight heater boasting a quiet operation...
The main differences compared to residential furnaces:
Lasko Ceramic Tower Space Heater
Portable Electric Heaters (Space Heaters)
Small, portable heaters can warm the “local” area according to the needs (be it bath before you decide to take a shower, bedroom before getting-up, living area to enjoy evening entertainment …..). They are popular solution for small RVs without a primary heating system and typically used “just in case” of chilly weather conditions (it can happen even in warm climate zones).
Often they are also used as a secondary heat source when the primary one (like Heat Strip or Heat Pump) cannot meet your needs.
Market offers variety of models with typical power range of 1kW -to- 1.5kW (for reference 1.5 kW is equivalent to approximately 5,200 BTU). Most popular types of space heaters are:
Note: The Positive Thermal Coefficient (PTC) Ceramic increases its electrical resistance with temperature. The effect is much stronger than in metals causing significant increase of resistance. This in turn limits the electrical current and dissipated electrical power (so the heat).
Olympian Catalytic Wave-3 Safety Heater
Portable Propane Heaters (Space Heaters)
Similarly to electrical space heaters, they are used to warm-up “local” areas inside of an RV and/or eventually outside on the patio. The main difference compared to electric heaters is the source of energy – in this case LPG. The outcome is clear – you can be warm and comfortable in out-of-grid environment. They warm the air by radiation so they are truly noiseless!
However this “freedom” of movement to the area known as out of civilization comes at the price. The propane heaters require “professional installation” (connection to the RV’s interior propane system), they use oxygen and generate “waste” gases (so they need good ventilation as well as CO and propane detectors!).
Well, many models can be fed by an “integrated” (throw-away) 1 to 2lbs LPG bottle. While it makes them fully portable and eliminates the need for professional installation, it puts an extra stress on you and on alarms system. Keep in mind that traditionally all LPG tanks are mounted outside of an RV, so the most vulnerable connection (the one used when replacing the bottle) in the case of leak is well ventilated. It’s still a dangerous situation however things are deadly serious when the leaking joint is inside of the RV. To increase the safety most propane space heaters (especially these for indoor use) are equipped with safety features like for example, Overheat Sensor, Oxygen Depletion Sensor (ODS) and Accidental Tip-Off Sensor – all of them shutting-off the gas valve (It is assumed that the CO and Propane detectors are part of RV’s mandatory features and it is your duty to make sure that they are operational).
All propane gas heaters have piezo-ignition system (time when you needed the box of matches is long gone).
The most popular types of propane heaters are:
Note: Buying the propane heater for your RV, you MUST make sure that it is the model designed for INDOOR use!.
Well, these are most popular RV heating systems that will make your trip enjoyable during chilly weather conditions with temperatures above 40's. However, if you are planing winter trips you may consider more complex and much more efficient heating systems.
See details at: --> Hydronic Heating Systems for RVs
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