We're working on Dave Lundgren's '89 Westy refrigerator, and I have to admit to being stalled for the moment. I'm hoping someone can show me the flaw in my logic. Here's the scoop: Dave told us the unit wouldn't cool beyond 10 deg F. below ambient while operating on propane, but made ice on house current. He cleaned the flue, checked flame everything seemed normal. Enter Valley Wagonworks. First we verified his observations - he was right on. Next we removed the unit, disassembled the burner box, cleaned the orifice and tube, used a boroscope to check the flue for obstructions, blew everything out with compressed air, put the orifice and burner back together enough to light and observe the flame before putting the burner box back together. We set it up to run on propane outside the van using a barbecue propane tank and new regulator at measured output (using a Dwyer 18-0-18 slack-tube manometer; Grainger, $54.00) of 11" WC. The burner always lights, the flame is proper height and color, never goes out. We reassembled the burner box and verified that propane flame was lit and heating - we got 386 degrees F. at top of exhaust stack. We then proceeded to make comparison temperature measurements at three places (ambient temp around top of fridge, temperature of absorber inside fridge, top of boiler tube). Measurements were taken over 2 days after operating unit for 14 hours (overnight) and then in mid-afternoon first on 110V then on propane. The readings are below. AMBIENT BOILER TUBE ABSORBER AC AM 91 289 29(ICE!) PM 112 298 51 DC AM 86 301 59 PM 110 295 85
The $64,000 question, of course, is WHY DOESN'T THE THING COOL AT THE SAME RATE WITH PROPANE WHEN THE AMMONIA-WATER BOILER IS APPARENTLY BEING HEATED JUST AS WELL OR BETTER WITH PROPANE??? I've thought about the temp control valve, but if my understanding is correct, that just regulates the propane flame height to trim it down thereby lowering boiling rate of the ammonia-water solution in the boiler. Since we have plenty of heat at the top of the boiler I'm guessing this is not an issue. Other notes: The van has not sat for long periods of time (correct me Dave, if I'm wrong about this) with the fridge in disuse, has worked properly (made ice in the desert using propane) until just recently. What am I missing? Coby Smolens Valley Wagonworks VW Bus and Vanagon Specialists "Intimately (but perhaps not intimately enough) acquainted with VW Vans since 1959" 1535 SF Drake Blvd, San Anselmo, CA 94960 415-457-5628 |
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