

| Subject: | Re: Dometic Fan |
| From: | Jeff Palmer |
| Date: | Wed, 31 Jul 2019 12:41:55 -0500 |
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 And believe me, I have a lot of unpublished data where I tested different 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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