Attention!!! Maybe some of these mods don’t work. Doing some tests now to confirm. Yes this is embarrassing 🙂
I’m going to try my best to not run down any rat holes in this post, for there are many when it comes to the fridge. I’ll try to stick to the mods that I recently made. Over this last winter I’ve had a couple of westy propane fridges in the workshop, in for some D&C ( that’s dusting and cleaning, not the other). With one of them, I tried out some ideas. First was to insulate the section of corrugated stainless exhaust pipe that really pumps out heat into the van. Just a couple of wraps of Fiberglas tape, exhaust pipe tape.
The next mod was a couple of aluminum plates clamped to the fridge cooling fins to help channel cooling air. I know others have made an enclosing shroud back there, I tried that about twenty years ago and I wasn’t very successful in getting a good fit. This time I reckoned that the plates would maybe do 80% of the job with 100% less effort.
In addition to the plates, I added a bank of three small, very quiet and low current draw, squirrel cage fans.
Here’s the test mule with the mods. At this time there was only one wrap of insulation on the exhaust pipe and I added a programable temperature controller and probe to control the bank of fans.
I bench tested this with propane, 120 V ac, and 12 V dc. I fiddled with a programable temp controller and finally decided that even though it was sort of fun to be able to adjust the fan set point and adjust the dead zone ( in effect, adjustable hysteresis) , it really wasn’t needed.
Also found that on propane, the exhaust pipe still gets hot. Not skin scorchingly hot as it was un-wrapped, but still a heat source. Decided to double wrap.
This weekend I duplicated the set up onto my own fridge. I had added a second fan to this fridge some time ago, and I had replaced the stock fan motor with a slightly larger unit. This was working ok, the second fan was fairly quite. Skirting round a tempting rat hole here when I say that I think the stock fan blade works as well as anything in that placement.
I removed that computer fan and installed the bank of three squirrel cage fans. The fans are wired in parallel to the stock fan. And added the plates.
Plates are held on by hooked ends, the straight ends threaded and nutted.
The fans are mounted to a bit of 1″ wide, 1/8″ thick aluminum. Little bit of a dog leg and screwed at one end, the other end cable tied to fridge tubing. It’s in there quite securely, no movement, no rattles.
Double wrap of insulation on the exhaust pipe.
I don’t think the insulation will have any adverse effect on the exhaust tubing. I think the stainless will take the additional heat.
A couple of tips on reinstalling the fridge. One thing I did some years ago was to re-thread the intake/exhaust flange for M4 bolts. The original sized holes had stripped out. The socket headed cap screws are nicer to use.
When you’re trying to line the fridge up to install the sheet metal screws inside the cupboards, a slim awl or a pin as shown is a great help.
And the propane connection to the fridge can be a little frustrating to attach. The line up might be off and the access is awkward. A short wrench is invaluable, this old family heirloom is what I use.
You know, I’m not an expert on these fridges but I’ve found that if all the components are working, the electrical connections good, and the combustion chamber ( and gas jet) is clean, then the fridge lights up easily. Believe me, I’ve struggled with the fridge at times, but I think those days are long gone.
Addendum, later that day…
Dgbeatty commented that I should look to the finned heat exchangers inside the fridge and re-do the thermal paste. That bugged me, I should have thought of that when I had the fridge out. I replied that I had tried to remove the fins years before but had no luck, they were stuck enough that I worried about breaking something. But I tried again and this time they came off.
That old thermal paste came off with WD40, then a rub with isopropyl alcohol.
Of course I don’t have a tub of thermal paste to re-apply, so I did what any redneck would do, I used anti-sieze. I don’t think that’s as daft as it seems. The MSDS for this anti-sieze states it contains 5-10% (by weight) aluminum powder.
And all back together. Replaced the the little CPU fan I had wired up to the top of the fins ( idea is to circulate the cold air, don’t use it that often) with one of the little squirrel cage fans. At the side of the fins. What the heck, it’s going to move some air.
#1 by dgbeatty on June 19, 2017 - 2:23 pm
I found that the interior fin unit needs to be removed, cleaned and reinstalled with fresh heat transfer compound. The original compound had dried many years again and was no longer effective at aiding in the transfer from the tubing to the fins. It made a good improvement in the overall performance.
#2 by albell on June 19, 2017 - 3:04 pm
Yes, good point. Some years ago I made a half hearted attempt at pulling the finnned unit. Didn’t come away with he amount of force I wanted to use. So I let it be. I probably should try again. Mind you I do get frost/ice on the fins. And I do get a good delta C, well as good as I’ve seen published elsewhere.
#3 by John B on June 19, 2017 - 10:57 pm
Will you be able to tell if your mods have really helped? I ask as I would love to go back to a 3 way fridge if I can get good efficiency. Tired of grovelling with compressor fridges/freezers and batteries and solar panels and charging circuits and running around camp like a twit with a volt and amp meter! Trips seem focussed on volts and amps and current draw and fear of flat batteries and not worth the pain anymore!
In Southern Africa also dealing with high summer temps that don’t help keeping the beer correctly chilled!
#4 by albell on June 19, 2017 - 11:14 pm
Yeah well …. good question . I’ve got some data gathered way back when with the same fridge but in a different van. I don’t mean the same type of fridge, I mean the same fridge! But in that van I had the westy city water inlet port gutted and a small fan added. This helped get the heat out from back to the fridge.
Anyhoo, that data is here
With our dometic fridges I think we are doing pretty good with a temp diff of 22C ( delta T , fridge and van). If only we could insulate the fridge better, but there is no room for that.
For us, up here in BC, on the coast, the fridge works pretty well. But anywhere hotter then…
#5 by oldfussbudget on June 29, 2017 - 2:47 pm
What I was taught about making up flare fittings is that you *must* align them ahead of time so that they thread up easily with the fingers, only use a wrench for final tightening. To do otherwise risks misalignment and leaks.
#6 by albell on June 29, 2017 - 4:09 pm
Right you are david. Mind you you can’t get the fitting started on the threads unless the copper is aligned. Well that’s my experience .
#7 by oldfussbudget on June 29, 2017 - 5:49 pm
I’ve gotten the one on the fridge started but had to use a wrench to tighten it. And it leaked. That’s when I bowed my head to what i’d been taught and frigged with it until it spun on by hand.
#8 by albell on June 29, 2017 - 6:15 pm
I’m not responsible for monkeys with wrenches torquing up bad fits
#9 by oldfussbudget on June 29, 2017 - 6:32 pm
#10 by oldfussbudget on June 29, 2017 - 6:33 pm
That’s a sweet little baby monkey wrench though.