Interesting observation by Richard about the drip tray.

Jim

On Wed, Jul 31, 2019 at 10:36 AM Alistair Bell <albell@shaw.ca> wrote:

> That’s true, and the back of the fridge fan moving air out back there
> doesn’t do anything to reduce the thermal mass of the cabinets, and the
> fridge has limited thickness insulation.
>
> It’s not a huge improvement, I’ve run a series of tests I published here
> on the list some years ago. Haven’t seen muchother data similarly
> comparing. And my data is pretty useless really as I had no control van to
> compare.
>
> And believe me, I have a lot of unpublished data where I tested different
> fans and fan on temp control changes ( programmable t stat).
>
> I do think that insulation around the exhaust pipe from where it exits the
> insulated shroud on the fridge, up to the external flue vent, works to
> reduce the radiant heat from the pipe.
>
> Perhaps the easiest and best bang for buck mod is to set up a Mylar coated
> space blanket on the outside of the van , magnets holding top of blanket to
> van just below the gutter, and rocks or pegs holding bottom of blanket to
> ground. Blanket angled a bit to keep it away from side of van. This
> dramatically reduces heat in the van from the sun, right on the area
> adjacent to the fridge.
>
> Alistair
>
> On Jul 31, 2019, at 8:02 AM, Jim. Felder <jim.felder@gmail.com> wrote:
>
> Overall, the comments about the water vent hot air evacuation schemes are
> probably the right idea for cooling. But if so, then it probably makes
> sense not to stop at just using the small hole of the water outlet but to
> use a window fan to evacuate air from the entire vehicle. I have had a
> pancake fan mounted in the window above the kitchen. It could be bigger and
> should be bigger. But it does help get rid of the high temps when the van
> gets hot. Best strategy seems to be to avoid the sun, but we don't always
> get a choice in that. A bigger fan to pull lots of air out would help the
> occupants and the fridge.
>
> Jim
>
> On Tue, Jul 30, 2019 at 10:05 PM Alistair Bell <albell@shaw.ca> wrote:
>
>> Like the others, I did the external vent thing many years ago on my
>> previous van. I do think it worked to reduce back of fridge temps.
>>
>> Caveat, it’s hard to determine the amount of the effect, none of us have
>> set up side by side vans , with and without, etc etc , to do real tests.
>>
>> Same fridge is now in my westy converted Syncro. But I don’t have the
>> external water hook up port to use as a fan vent. And I have done lots of
>> fooling around with mods on the fridge in its new home. Different and
>> multiple fans etc.
>>  And I have insulated the exhaust pipe from fridge , the stainless
>> corrugated pipe, with Fiberglas exhaust wrap.
>>
>> I think that helps reduce the temps back there.
>>
>> The incremental improvements in getting the heat away from the back of
>> the fridge does not hugely improve things, but I think it does help.
>>
>> Alistair
>>
>> > On Jul 30, 2019, at 6:22 PM, David Beierl <dbeierl@gmail.com> wrote:
>> >
>> > ---------- Forwarded message ---------
>> > From: David Beierl <dbeierl@attglobal.net>
>> > Date: Tue, Jul 30, 2019 at 9:21 PM
>> > Subject: Re: Dometic Fan
>> > To: David Boan <dboan@outlook.com>
>> > Cc: vanagonlist a <vanagon@gerry.vanagon.com>
>> >
>> >
>> >
>> >
>> >> On Tue, Jul 30, 2019 at 9:08 PM David Boan <dboan@outlook.com> wrote:
>> >>
>> >> I wonder what "working well" means with a dometic fridge, so I gathered
>> >> some numbers. ...
>> >>
>> >> Running on 12v from the house battery, engine not running, for one
>> hour,
>> >> the temp of the cooling fins inside the fridge is 49 (measured with an
>> >> infra-red sensor).  The outside temp, both in my garage and inside the
>> van,
>> >> is 98.  The temp on the outside of the fridge door is 96 (an
>> indication of
>> >> marginal cooling loss?).
>> >>
>> >> During that hour, the house battery went from 12.5 volts to 12.3
>> volts.  I
>> >> do not have resistance or amp data to know if this is reasonable.  I
>> >> anticipate running this from my solar panel, which will keep the
>> battery
>> >> charged during the day, but obviously not at night.  I am curious to
>> >> calculate how much the battery will be drawn down after 12 hours.
>> >>
>> >
>> > The fridge on DC will draw 7.5 amps continuous, with no thermostat.
>> >
>> >
>> >>
>> >> I then switched to 120v.    Understanding the fridge was already cool,
>> I
>> >> wanted to see if 120v would get it cooler.  After an hour the same spot
>> >> (cooling fins) were 40.  The outside temp was 97.
>> >>
>> >
>> > Run it for 24 hours on 120 VAC with thermostat turned to max to get your
>> > benchmark.  These fridges can't move much heat, so everything happens
>> > slowly with them.
>> >
>> > It's been a long time, but I think box temp (not fin temp) 40F below
>> > ambient is doing pretty well.  Someone will correct me on that.  Keeping
>> > the van ventilated with the skylight for a chimney effect and shading
>> the
>> > fridge side from the sun will help.
>> >
>> > In reasonable weather they can make ice in the little toy ice trays.
>> > Slowly.
>> >
>> > One of the things that will kill performance is if the fins inside lose
>> > intimate contact with the cooling tube.  May help to pull the fin
>> assembly
>> > off, clean the old heat sink compound off both surfaces, and reinstall
>> with
>> > a *THIN* I mean Really Thin layer of compound.  Ideally you want only
>> > enough to fill the irregularities in the apparently smooth surface,
>> because
>> > heat sink compound is actually not a very good conductor.
>> >
>> > In theory operation is equally effective on all three modes.  In
>> practice
>> > DC tends to perform less well unless the wiring is absolutely tip top,
>> > because a half volt drop at 12V is a much greater percentage than at
>> 120V.
>> > Gas normally works as well as AC.  Again, there is not thermostat on DC.
>> >
>> > Yrs,
>> > d
>>
>