Date:         Sat, 21 Jul 2007 21:58:53 -0700
Reply-To:     Michael Elliott <camping.elliott@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Michael Elliott <camping.elliott@GMAIL.COM>
Subject:      Re: Where is The Heat Going?
Comments: To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
In-Reply-To:  <000501c7cc01$5415b1d0$0301a8c0@MASTERPC>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Dennis Haynes typed:
> http://gasrefrigeration.net/dom_techdata/MAN_SM.PDF
> http://www.fiberglassrv.com/manuals/dometic-service-man.pdf


[snip]

> FWIW the wattage of both the 12 volt and 120 volt heaters is 85. The
> BTU input on gas has to be fairly close as too much heat will also stop the
> unit from working and damage it.

It makes sense that the amount of heat from the flame that is applied to
the working bits of the refrigerator has to be close to that provided by
the electric heating elements, so we can assume that the flame puts out
at least 290 btu/hr (equivalent to 85 watt hours). But it seems to me
that the heat of the exhaust gases coming out the flue represents waste
heat that is in addition to the 290 btu/hr that the working bits are
using. Since the exhaust flue and the combustion chamber radiate some
heat, my guess is that the heat behind the refrigerator will be greater
with the flame than with the electric heating elements. I could be wrong
about that, but I'll bet a bottle of good IPA on it.

Anyways, the original question was whether the Norcold generates as much
waste heat as the Dometic. The fact that once both reefers have cooled
their foods the Dometic dissipates 85W/hr steady-state while the more
efficient Norcold comes in at about 15W/hr (or less, depending on
ambient temperature) suggests that the Norcold dissipates at least 5
times less heat. After all, the power going into the refrigerators has
to come out as heat, and maybe in the case of the Norcold, a wee bit of
compressor noise.

I'm surprised that there isn't a propane consumption rate spec for the
RM 182 floating around.

--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR