Date:         Tue, 17 Oct 2000 19:08:07 EDT
Reply-To:     Ssittservl@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         S Sittservl <Ssittservl@AOL.COM>
Subject:      For Carver P4 owners: P4 performance questions
Content-Type: text/plain; charset="US-ASCII"

Carver P4 owners:

I'm not convinced my Carver P4 furnace is heating as well as it should.
Can other P4 owners tell me if these results are similar to what
they're getting?

(1) Fan speed.
If I set the heater to "fan only (no heat)", and turn the thermostat
(fan speed) dial all the way up, the fan goes really, really fast
and blows a lot of air.

But, when I set the heater to "high heat", and turn the thermostat
all the way up, the fan only goes, at most, about half that speed -
even on a 40 degree day with the doors open, no matter how long
I run the heater.  I would think a higher fan speed would heat the
van better.

On "low heat", the fan speed varies between "pathetic" and "is this
thing on?".


(2) More on fan speed
Fan speed seems to vary almost at random.  I understand the
slow-speed-startup-until-it-gets-warm idea, but even after that,
the fan will speed up and slow down at various times, without any
obvious relationship to van temperature that I can determine.


(3) Heating capability
With the pop top down, and the windows closed, on a 37 degree night,
with the thermostat all the way up, and the furnace on "high heat",
the furnace maintained a temperature of 75 degrees inside the van,
running constantly, without stopping, with the fan running at its
highest "heat" speed the whole time.  It managed this for about
8 or 9 hours before draining my battery.

That's more than warm enough, or course.  But, it corresponds
to only about half way up the thermostat dial - a lot lower
than it was set to.  I would have expected it to be able to
maintain room temperature without running constantly.  (I expected
it to cyle on and off.)  I also thought it would get the van hotter
when set to maximum.

Sometimes, the heater seems to do less well, even at the same
exterior temperature, and can only maintain about 69 degrees
running constantly on high.

When set to "low heat", even with the thermostat on maximum, the
van stays pretty close to the outside temperature.  "Low heat"
doesn't seem to be useful.


(4) Heating efficiency
If I turn the 5200 BTU/hr Westfalia stove on full (both burners) on
a 40 degree day, the van's interior temperature will be about
80 degrees in 10 minutes.  But if I turn the 7500 BTU/Hr P4 on full
on the same day, I might make it to 70 degrees after an hour.  That
seems like a lot more gas for a lot less heat.


(5) Subjective experience
The furnace doesn't seem to be able to keep the van comfortably warm
(say, 72 degrees) on a moderately cold (around 40 degree) night unless
it's running pretty much constantly, on high, and the the pop top is
down.


So, how does my experience compare with other P4 owners'?

Some background:
My original P4 installation is described on my web page at
"http://members.aol.com/ssittservl/Westfalia".  Since that time,
I've added a ducted cold air return, and replaced the flue blower/
proving fan and control board with replacements sent by Carver (free).
The blower/fan and control board were replaced at Carver's
suggestion - I'd been getting a "flue blocked" error from the
heater, but the flue clearly wasn't blocked.  Their tech.
support said the problem might be the "proving fan" (which makes
sure the flue air is flowing freely) or the control board.
I replaced the control board and the problem remained; I
replaced the blower/fan, and the problem went away.   (This
blower/fan only handles combustion air - a separate blower/fan
handles the heated "room" air.)

Thanks for any help.

                               -Steven Sittser