too much ventilation for fridge??

[Rick G]

Hi. I have a Dometic RM 211 fridge, the original in my 1980 Trillium 4500. Last summer I was trying to get it working better in hot weather and solve a problem. Right now it is in storage, but spring will be here soon-ish, so I am starting to think about it again.

It had been working fairly well but not great on hot days. Last summer I played around with the vents and installed baffles and a fan for much better ventilation, which improved the performance measurably when parked. It works well on all of gas, 110V and 12V, at least when parked.

The other issue was that the fridge propane flame would blow out while driving. I had that same issue in my previous Boler with a different brand fridge and solved it by partially covering the bottom air vent while driving to cut down on the wind. However, nothing worked for this fridge. I tried furnace filters, baffles, blocking part or all of the bottom vent, a Plexiglas panel inside to direct air elsewhere, but nothing worked. The Dometic design with the flame on the right means that it is always in path of the wind when driving. My other fridge had the flame on the left, making it much easier to keep out of the wind for a typical driver’s side installation.

Anyway, after installing the improved venting in the fridge, the problem remained. Every time I drove more than about 50 km/hour, the flame would blow out. I have cleaned and checked every part of the propane system and it is all in good shape.

So, finally at my wife’s suggestion I used a garden leaf blower to simulate the wind while the trailer was parked in our driveway. The flame remained on while the wind was directed at the bottom vent, but immediately blew out when directed at the top vent. The top vent is the exhaust, so this was unexpected. After more research I found that the wind was blowing down the chimney and blowing out the flame, even though the fridge had the original 90 degree corner cap on the top of the chimney which is supposed to prevent that.

So, then I tried building sheet metal boxes around the chimney flue cap and extending the cap to prevent the wind from reaching the flame while still allowing the chimney to work. That had some slight success. Then I installed an additional sheet metal baffle around the chimney flue cap to prevent the wind from directly reaching the chimney. That finally worked, and now I can drive at highway speeds without blowing out the flame.

Unfortunately, that did not solve my ultimate problem. Now, although the flame is on, the fridge does not cool while driving. The heater and absorption coils on the back of the fridge remain dead cold even after a few hours of driving, even though the flame remains on. I have also run it on 12V (which works well when parked) and it does not cool on 12V either while driving. The coils at the back remain cold while driving on 12V or gas.

So, finally, my question for which I hope someone can provide assistance. Is it possible to have too much ventilation for the fridge? Should I be looking at less perfect ventilation so that the coils can heat up enough to let the ammonia solution evaporate? It seems that perhaps I should be restricting the airflow back into the fridge coils from the top, or preventing the wind at least. What do you think?

Thanks,
Rick G

[Joe MacDonald]

Rick, to be safe, I would recommend using 12 volt when driving, not gas, run a separate line from your tow vehicle and use a solenoid which disconnects the power when you shut off your tow vehicle so your battery doesn't drain.
If you were to forget to turn the furnace off, you could be the recipient of a big boom at a gas station, also some locales don't allow you to travel in tunnels with propane, let alone with it hooked up and turned on

Joe

[Thomas G.]

My brother was recently towing his travel trailer and had a blowout. He was running the gas fridge and the tire parts knocked off the propane line. Fortunately no boom, but scary.

There might be something here for you in diagnosis your ventilation problem.

Refrigerator Madness - Been There Done That - Vanagon Tips and Tricks from the Vanagon Mailing List

[Rick G]

Originally Posted by Thomas G.

My brother was recently towing his travel trailer and had a blowout. He was running the gas fridge and the tire parts knocked off the propane line. Fortunately no boom, but scary.

There might be something here for you in diagnosis your ventilation problem.

Refrigerator Madness - Been There Done That - Vanagon Tips and Tricks from the Vanagon Mailing List

Thanks, an interesting article. I also received a PM about this with some suggestions to consider the different parts of the cooling unit and the different requirements for cooling for each of them, which was very helpful. I am really not looking to re-open the unending and passionate debate about propane safety while driving, just for assistance in figuring out how to get good cooling on the ventilation fins while allowing the burner to heat up. I have had a fuel pump die in my van and leak gasoline all over the engine while driving, which did not cause a fire but lots of smoke, so I am well aware that gas of any kind has a (very small) chance of disaster.

Thanks,
Rick G.