HYBRID RV GAS ELECTRIC FURNACE KIT
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.
Article and Photos Provided by CheapHeat™
