Brrrrr! Getting to Know Your RV Heating System

HydronicTrailers and motorhomes are built to be comfortable, even when the temperatures drop. This extends the camping calendar and allows people to enjoy the quieter off-season campground atmosphere. Also, this can result in more availability and reduced prices. So let’s look at just what keeps the living quarters at a comfortable temperature during those cold nights.

Check out the following heating systems and determine which one is right for you. It may influence your next RV purchase.

Furnace or Hydronic

Today’s RVs come with either an RV furnace or a hydronic heating system. The furnace is basically a consolidated propane fired burner equipped with circulation and vent fans. It is controlled by an adjustable wall thermostat, just like home. When heat is called for, an electronic igniter lights the burner. When the heat chamber reaches a certain temperature the fan(s) are thermostatically started. The RV furnace is very reliable with limited maintenance requirements.

The hydronic heat system serves a dual purpose: interior heating and heating the hot water circuit. These multi-tasking units are diesel or propane fired. They also have the ability to operate on AC shore power. The electric element(s) and burner heat a closed circuit filled with boiler antifreeze. The heated antifreeze solution is then pumped to several air movers which are strategically installed in several locations within the living area. The air movers use small radiators with fans to transfer the heat as needed. The hot water circuit is heated via a heat exchanger configuration and is capable of supplying continuous hot water. While there are yearly maintenance requirements, this method of heating delivers the upmost of comfort providing consistent temperatures inside and uninterrupted hot water.

Both the RV furnace and the hydronic system are designed also to feed warm air into the basement. This feature protects the pipes, tanks and related plumbing from freezing, in many cases, even in extremely cold conditions.

AC Reverse Cycle Heat Pumps

In addition to having one of the fore mentioned RV heating systems, many units come with optional AC reverse cycle heat pumps. These are capable of also heating the entire living area. However, these only work when temperatures are at least several degrees above freezing. Below that temperature the heat pumps become inefficient. Most, if not all, so equipped RV’s are configured to change automatically from “Heat Pump” mode to “Furnace” or visa-versa should this temperature be reached. So it is possible to go to bed with the heat pumps operating, wake up to the furnace working, and observe the heat pumps once again restart as the morning warms up. Pretty tricky!

So, keep your heating system working well and enjoy the pleasures of off-season camping.

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  1. Peter you left out the Hybrid Electric Heating System “CheapHeat” that hooks to existing RV gas furnaces and gives the consumer the chose to select eater gas or electric as a heating source when collect to power at the RV park.
    RV Comfort Systems, a Washington based firm has successfully engineered an electrical heating option, an add-on assembly to any RV propane furnace, so today’s RVer can simply choose propane or electricity to heat the interior of the coach. Called the CheapHeat™ System, this unit is mounted directly downstream of the existing gas furnace and employs tungsten heating coils
    powered by 120 or 240-volts AC to provide the heat. The 12-volt fan motor on the furnace then pushes the heated air throughout the distribution ducting in the coach. It can be configured into three different wattage ratings, 1,800, 3,750 and 5,000 watts, depending on the shoreline cord limitations. According to the manufacturer, the electrical heat source is 100% efficient; all heat produced is forced through the ducts since the heating core itself is mounted in the direct flow of the distribution system. Compared to the burning of propane for comfort heating, which is approximately 60% efficient, the all-electric CheapHeat™ option is a viable option for serious coach owners to consider.
    In addition to the heating coil assembly, the other main component of the system is the solid-state controller. The controller is the very heart of the CheapHeat™ system. It communicates directly with the existing wall thermostat and the fan motor so all the user has to do is simply select Electric or Gas on a conveniently installed wall switch. This well designed and sturdy controller is engineered and applicable to both 30-amp and 50-amp shore power configurations. It coordinates all the functions of the existing propane furnace with the added electrical heating coil assembly. Considering actual load demands, all internal wiring components and connectors are purposely oversized by at least 30%. And every component part in the CheapHeat™ controller is UL® Listed and mounted in an industrial grade NEMA-1 UL® Listed/certified metal box.

    The coil assembly is safeguarded against failure by redundant methods making the CheapHeat™ unit totally safe and permanently installed, which is certainly not the case when RVers use portable space heaters for instance. Aside from overkill on the sizing of the components in the controller, a bi-metal high limit safety switch wired into the coil assembly protects it from any over-temperature situation. Additionally a failsafe device called a fusible links is included for the common “leg” of the coils, (see photo). Which acts as an in-line circuit breaker protects against any over-current and/or over heat problems. With redundant integral safety measures, plus the fact that no carbon monoxide is produced using electric heat, the CheapHeat™ System is deemed quite safe and viable. The only connection between the CheapHeat™ and the existing propane furnace is a simple wiretap on the fan motor conductor. The existing furnace circuit board and all associated relays of the propane furnace are simply bypassed when using electric heat.

    Tests have shown that the CheapHeat™ unit successfully heats the motorhome in less operating time, meaning the furnace blower assembly works less to heat the same space as burning propane. Here’s why.

    All propane-fired forced air furnaces require a pre-purge and post-purge cycling of the blower assembly to remove any trace of unburned propane and other gases that might yet exist in the sealed combustion chamber. Some pre-purge cycles can approach a full minute, while post-purge cycles can run up to about 90 seconds each. And if the furnace is equipped with a three-try circuit board, the run-time on the fan motor increases yet again. With the switch placed to electric mode, the fan motor only operates when heat is being produced. I receive emails every season from disgruntled RVers who experience this pre and post-purge cycling and cannot understand why the furnace is blowing cold air. Unless a fault exists, it’s just the nature of propane burning furnaces. For every heating cycle, there is a full 2.5 minutes of runtime with no flame or heat being produced.

    Because of 40% energy loss through the flue along with the pre and post-purge cycles, the realized heat output into the coach with a 40,000 BTU propane furnace, for example, is reduced to about 18,000 BTU an hour when measured at the discharge registers. The CheapHeat™ system, meanwhile, produces a true, one-to-one BTU per hour heat output at the registers. Another factor to think about; it’s not uncommon for the propane furnace to purposely overshoot the temperature setting of the thermostat to compensate for the purging cycles. The elimination of this pre and post-purge cycling is a welcome relief to RVers, because it simply adds to a higher comfort level for the occupants. The CH50-DH50 is comparable to a 40,000 BTU propane furnace (it does, however, require 50-amp shore power service).

    The CH50-DH37 is akin to a 30,000 BTU propane furnace and also requires 50-amp service. The smaller CH50-DH18 is equivalent to a 20,000 BTU propane furnace but only requires 30-amp electrical service. If your existing gas furnace does not have adequate space for the Add-On unit directly behind it, or you’d really like a furnace positioned on a partition wall in the galley, for example, perhaps the stand-alone CheapHeat™ heater is something to consider.

    For additional information regarding the complete line of CheapHeat™ products, visit;

  2. Peter Mercer

    Peter Mercer

    Thanks Larry, great information. I only have a limited space per post making it difficult to encompass everything. So I only covered the most common units. Thanks for your very detailed comment. It is appreciated by all.

  3. Anonymous

    My heater is not heating my unit. I do know that the heating coil for the fridge has gone out. Is there any correlation here??? I am FREEZING!!! The heater is on 99!