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Old 11-23-2018, 11:51 PM   #11
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It's been about 10 months since I ordered them off Amazon, but you found them. Thanks for updating the links.
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Old 11-24-2018, 04:33 PM   #12
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Default Fridge woes

My class B, a 1973 Hall GTC, has the original Trav’ler 3-way reefer, which still works well. The fridge has minimal electronics and nothing is automatic except the thermostatic controls: everything else is controlled by manual mechanical switches at the whim of the operator. There is literally no board to fail, so it doesn’t. The coach builders were hip to the needs of gas operated refrigeration and provided a minimum of 1.5” high density foam insulation not just behind the refrigerator cavity (chimney), but the entire coach as well. The makers of the fridge clearly called for two vents for proper operation: one at the top to let the heat out, and one on the side at the lower end of the cooling coils to let the outside air in. For a system to operate as designed there Must be a method of providing adequate airflow without returning the heated air to the living space of the coach. My question is, if the fridge doesn’t work well, why not install an actual roof vent? It seems that a lot of effort is going in to getting things to work without actually following the installation instructions of the refrigerator’s manufacturer. Or am I missing something?
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Old 04-14-2019, 03:25 PM   #13
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Thumbs down Gas Absorption performance mods

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Originally Posted by peteco View Post
I bought a fan called the Snyder fan system, which helped a little. The Snyder setup is no longer available, but I think there is a better fan setup than this that I will describe later.

I think the upper fan installation and bringing the vent cavity to Dometic specs had the most effect.
Can you give some more guidance/pictures on the installation and airflow behind the unit? My unit (Roadtrek Adventurous RS) seems to comply with the Dometic installation requirements (see pic, looking down from upper vent), but I can see where better direction of airflow could improve performance. I am thinking having a pair of computer style fans exhausting the upper vent would be a help, and see where insulating the exterior wall could also help.
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Old 04-14-2019, 08:45 PM   #14
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It is hard to tell from your picture if it meets Dometic install recommendations. One thing that looks like it could adversely affect cooling is the large gap between the evaporator fins and the wall or exhaust grille. I modded mine to eliminate this gap.

I am in Hampton VA, where are you in VA? I would be glad to look at your setup and make recommendations.
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Old 04-14-2019, 10:28 PM   #15
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Default Gas Absorption performance mods

My dometic manual gives 20mm space and I am sure there is more than that. I am thinking some insulating material and a baffle so that rising air is directed only thru rather than around the fins, plus some kind of booster fan(s) exhausting at the top would improve things. Would likely put 1 or 2 12v fans on a thremotatic switch triggered by temp in top space.

I am located in Springfield VA. Will be going down the penninsula in mid May.
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Old 04-15-2019, 01:03 AM   #16
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One thing that looks like it could adversely affect cooling is the large gap between the evaporator fins and the wall or exhaust grille.
Sorry, I meant to say condenser (not evaporator).
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Old 04-15-2019, 01:15 AM   #17
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Here is a sketch from a Norcold install manual. It makes sense to me to make sure the baffle extends all the way up to the condensor fins so all the vent air passes through the fins. This is essentially the baffle box design I added to my 210.
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Old 04-15-2019, 01:30 AM   #18
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Peteco is definitely correct in his baffles, closer is better. This is a classic gravity chimney so all the same "rules" apply as they would to any other application. I think his setup is quite good.



Any hot area should be baffled horizontally so air can only go in the bottom and out the top creating maximum velocity from the heat rising. No "cold" areas should be able to pass any of the air from low to high for the same reason.


If you have two hot areas, and especially if one is lower than the other, it is best to have a vertical baffle between them if possible. To prevent the heat from the lower one going through the higher one. Essentially just two chimneys of the smallest area possible. In an RV gas frig, the boiler is usually much hotter than the condenser air and has lot of hot exhaust gas, so isolating it is a good idea.



Fans will work the best if right at the inlet or exit of the chimeys or ducted to those areas either as a push or pull fan. If not directly blowing or sucking the chimney air, the fans will often just "loop" the air they have. This especially true on upper Roadtrek vents unless you block off all of the vent except the fan blowing out area, to prevent looping. Ducts to the chimney tops essentially do the same thing.
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Old 04-15-2019, 01:40 AM   #19
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Quote:
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In an RV gas frig, the boiler is usually much hotter than the condenser air and has lot of hot exhaust gas, so isolating it is a good idea.
I have considered trying to wall-off or isolate the boiler to keeps its heat away from the absorber and condenser. It would probably help but the fridge is now working OK so I haven't bothered with it.
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Old 04-15-2019, 01:53 AM   #20
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Quote:
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Fans will work the best if right at the inlet or exit of the chimeys or ducted to those areas either as a push or pull fan. If not directly blowing or sucking the chimney air, the fans will often just "loop" the air they have. This especially true on upper Roadtrek vents unless you block off all of the vent except the fan blowing out area, to prevent looping.
I think the Dometic recommended fan location does cause "looping" of the airflow inside the vent cavity. I had poor fridge performance with the fans located in the middle like Dometic recommends. I have found the upper exhaust duct location with a centrifugal fan to work well, but "short circuiting" of the exhaust air back into the exhaust duct is a potential problem. So in hot weather I have blocked off all the exhaust duct opening except for the fan exhaust. This has improved the performance while driving as well as no air can be forced into the exhaust duct. Another benefit is keeping rain out, which is especially a problem with the 210 and its curved wall. Other vehicles with a straight vertical wall should have lesser problems with water intrusion. I remove the exhaust duct blocks in cooler weather to allow natural convection of the air.
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