Date: Wed, 31 Jul 2019 12:41:55 -0500
Reply-To: Jeff Palmer <w.jeff.palmer@ICLOUD.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Jeff Palmer <w.jeff.palmer@ICLOUD.COM>
Subject: Re: Dometic Fan
In-Reply-To: <CAFnDXk2eXqeNmGV2u+HEeUCTYOx=VamP-p1HcXmKHA3wGNN9ww@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
What drip tray and who is Richard?! Is that comment in this thread or are my progressives acting up again.
Sent from my iPhone
> On Jul 31, 2019, at 10:51 AM, Jim. Felder <jim.felder@gmail.com> wrote:
>
> 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 And believe me, I have a lot of unpublished data where I tested different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
>>>
>>
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