From: John De Armond
Subject: Re: Freezing nights in a 5er
Date: Fri, 10 Mar 2000 14:40:23 EST
Newsgroups: rec.outdoors.rv-travel

Steve Wolf wrote:
> 
> Re:  Using electric heaters
> 
> Neon John <johngdNOSPAM@bellsouth.net> wrote in message
> news:38C842B7.B802D396@bellsouth.net...
> > instead of the propane I have to lug around.  My project of the week
> > is to install the internals of this heater in a cabinet to get it
> > out of the floor and to integrate it into the thermostat control
> > system.
> 
> Damn it.  Just what I need, another project.  This makes so much sense that
> I, too, will be building all of mine in.

Yup.  Those ceramic heaters are really nifty.  I hadn't paid much
attention to how they work until I took mine apart to get the
heating block out.  the heat is generated by a positive temperature
coefficient thermistor ceramic matrix layered between aluminum
fins.  The stuff is intrinsically self-regulating.  Block the air
flow, the stuff heats up some, its resistance goes up and the heat
production drops proportionally.  Super safe.  OTOH, force MORE air
through it and it really pops out the heat.

> I would suggest separate thermostats.  The kids like it warmer (in the front)
> than the wife and I like it in the back.

Well, in my little 20 ft Class C, that would be overkill since wifey
and I could lock arms and touch walls front to back :-)  Any kid in
the rig would be defined as unattended and in accordance with our
restaurant policy, subject to being skinned and BBQed.  Besides,
I've gotten kinda spoiled at home with the electronic auto crossover
thermostat.  I can have the bedroom air conditioned to a comfy 60
degrees at night and then have it automatically heat up to 70 as the
wakeup call.  I want that in the RV too.  What I plan on doing is
using a multi-stage crossover thermostat that will stage in the
electric heat first and then fire the furnace if more heat is
needed.  The White-Rogers unit I use in my restaurant does that
seamlessly, only with the fuel sources reversed.  The nice thing is,
in the W-R, the staging doesn't require an additional deviation from
setpoint like an old mechanical one does.  If the first stage isn't
causing the temperature trend to head in the right direction after a
few minutes, the next stage is brought on immediately.  In the RV,
that means that when I unplug from shore power, the thermostat will
seamlessly and without my intervention transition over to propane
heat.  Slick, eh?   

The white-rogers 'stat can be jumpered to run on internal batteries
and not require 24 VAC from the system so it will work fine on RV
systems.  I'm rewiring my Coleman rooftop  unit when I have it off
next week to replace the gasket.  The "fan" contacts on the stat
will control the fan and the "compressor" contacts will control the
compressor just like at home.  I really don't like the fan running
all the time, the way it's wired now, and the built-in thermostat
has way too much deadband for my tastes.  Already have the little
relay box made, just need to get to the roof unit.

> 
> I already have thermostats on them.  Info on:
> http://www.wolfelectric.com/family/motorhome

I really like your site.  Especially that little footnote at the
bottom of each article.