Sure would be nice to do this in the GMC
SOURCES FOR POSSIBLE PARTS
In my experience you do not need a huge
amount of BTU's when using a hydronic system, because the heater can be
burning moost of the time without being a nusance like air heating. No
noise, no wind.
The tank is small because the whole
system is waterfilled and circulating. The tank is only for expantion.
You could compare it to a On demand hot water system. That is why a
water heater is not a good alternative. No need to reinvent the wheel,
that has already been done a few hundred times.
I'm sure there are other manufacturers,
but I know these two will give you a good product. If you need
help, just ask .Marc
Heater register by Red Dot Corp. in Washington found by Eric
I received the 24VDC Red Dot Corp. Auxiliary Heater yesterday.
They wouldn’t take my low-ball offers, so I paid the $39.99
asking price plus $9.21 shipping. I am glad I ordered it and will get
another for the rear, or for future propane/hydronic heating.
No documentation is provided with the product. Construction is of
high quality, suitable for use in a GMC Motorhome. The casing is a
heavy plastic. The blower is the dual squirrel cage type, and the core
is copper with aluminum fins. There are three wires terminating in an
automotive type plug,, which I quickly decided to cut off and replaced
with crimp-on bullet connectors. The three wires provide two blower
speeds. All my tests were conducted on the high speed.
Red dot’s spec for current is 7.7A @ 13.6VDC. That spec
is for the 12V unit. While this is a 24V unit, I gambled that it would
provide adequate airflow running off the unregulated alternator output
that the dash air blower runs off of when on high. I haven’t
measured this voltage, but expect to see 16-18VDC when I do. The
blower moves a lot of air at 24V voltage (2.2A) and is pretty noisy. On
12VDC it draws the expected 1A and still moves air. It ought to move
plenty of air at 16V. I won’t install this right away, but
look forward to the additional winter heat it will provide while on the
Overall, this is a quality unit available at a great price. All
the others I’ve been able to find are at least $90. If
you’re thinking of adding an auxiliary heater, I’d
recommend getting one of these while their available. I’ll
post results and pictures when I get around to the project.
Red Dot has re-listed the unit. Here’s the link.
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