6.7 Cubic Foot Fridge Performance

[Parker]

I posted a few comments about our return trip from Chilliwack with our new 19, which included some challenges with refrigerator performance. Essentially, temps in the upper 90s resulted in the fridge not cooling well enough to avoid some spoilage, often getting into the high 40s, low 50s inside during the heat of the day. Propane, 120V, and 12V all about the same. We have been using a cube fan inside to move the air around. I've read through the following thread, which provided some ideas, but it deals primarily with the 5 cubic ft model (hope it comes up as a link).

http://www.escapeforum.org/forums/f9...road-1711.html

I've also downloaded Dometic's installation instructions and their document about baffle installation. These are interesting, but not entirely relevant to the 6.7 installation in the Escape. So I thought I'd kick off a new thread for the 6.7 cubic foot model, just to see how others are doing and whether any improvements have been made (if needed).

I have emailed back and forth a couple of times with Reace, who suggested removing the plywood baffle installed just above the lower grill. This baffle is called out in the Dometic instructions, apparently with the idea of directing cooling air closer to the cooling fins, which would be just above this with a smaller fridge. However, the cooling fins in the 6.7, where we want the refrigerant to start condensing, are way up above this baffle. So the baffle is unfortunately restricting air flow, and probably not helping to direct cool air over the fins up near the top of the unit. Makes sense to me to remove it; would like to try moving it up, but that would be tough. I removed it yesterday, and with just one day's operation I can't see much difference.

The fridge is nicely sealed on the sides, so no issues there. I'm curious about the top. Dometic warns against leaving a space on the top of the unit where hot air can stagnate, but it's hard to see up there. I may pull the vent cap off to have a look unless someone has already checked this and can tell me this area is effectively blocked off.

I would like to insulate the outer wall of the Escape above the lower grill, all the way to the top, but the propane burner exhausts up in there and I would have to be really careful not to interfere and also use a non-combustible material. Perhaps some aluminum flashing could be fashioned into a baffle to help direct the air where it needs to go while at the same time reflecting some heat back out through the fiberglass wall.

I have read about installing fans to help with the air flow. Dometic sell a couple of fans, intended for a different sort of installation. Still, a couple of fans may be worth trying. I really don't know how effective they would be while driving, but may at least help while parked.

Okay, this has been a bit long, but I thought I'd put it all out there at once. I would really appreciate hearing from others, including those who are having no problems with this fridge!

Parker

[float5]

Parker, I am not sure that I would expect to get adequate cooling with any of our models with those kinds of temperatures. Of course, hardly ever opening the door may help. We also have a fan to move the air around. I sometimes use icepacks in the crisper and one or more can be put in other areas. We have always had the freezer freezing packs well so just have to have enough packs to be able to exchange them.

[Parker]

Fair comment. I failed to mention that we just got back from four nights out with daytime temps only in the mid 80s. The fridge just barely did okay, running on its highest settings. When we picked it up, Dave said the middle setting should be adequate, so perhaps our expectations have been too high. Of course that was in Chilliwack at the time. I can't help thinking it should work a little better. We have also taken to packing some ice in it when it's really hot. I guess we could be freezing freezer packs over night as well. I've also been meaning to ask if anyone is running with the freezer section removed and how it performs that way.

[hotfishtacos]

Parker, I explored probably every option to get the most out of the cooling system in my similar (but smaller) refrigerator and the changes that had the greatest impact on cooling were making sure the gas pressure in the low pressure system was up to spec...mine was too low so I adjusted it upward increasing the size and temperature of the burner flame...and improving the baffle behind the unit by removing the plywood baffle and installing a "Reflectex" baffle that I made which effectively covered the back of the refrigerator going up beyond the top coils. It included an angled baffle at the bottom. This change forces the air up through the coil system, avoiding the dead space area behind the refrigerator. BTW, your refrigerator has two fans mounted to the back just below the top coils. It comes standard that way. If the temperature gets high enough the fans will come on automatically. They are connected to a sensor switch on the top coils.

I learned that absorption refrigerators are not nearly as good and efficient as a pump type system like the one in your house and you have to know that and manage the unit differently.

• Plug in the refrigerator at least 24 hours before a trip and partially load it so it is cold when you leave. Fill it with the rest of your goodies before you leave.
• Put at least one circulating fan inside the refrigerator to move the air around.
• Always put pre-refrigerated (pre-cooled) food inside. The unit needs to keep it cold, not make it cold.
• The bottom of the door is the warmest part of the unit so although it looks like the right place to keep milk it is not the best place. Close to the coils is where to store the most temp sensitive foods.
• Plan what you are going to do quickly when opening the refrigerator and then close it quickly.
• Putting frozen food in the refrigerator from the freezer to defrost helps keep the refrigerator colder.
• Don't overload it so air can circulate well.

One mistake we used to make was at breakfast. A lot of stuff comes out of the refrigerator and then stays out for a while, warming up. Then when everything is put back it takes a very long time to cool back down. In fact, we now deposit a small deposit of the condiments we will sue for a meal so all the containers can go right back in the unit quickly. Good luck!

Steve

[cpaharley2008]

Parker,
Does your 19' have the roof or side mounted exhaust?. My 19' had the side mounted and smaller Dometic 3.0 and although it operated fine, there was a lot of dead air space. I inquired about the new refer in the 21' and was told that it fits like a glove and the walls are insulated and dead air space eliminated.

[Ruthe]

We had a dometic in our airstream and maybe my memory is fuzzy but I don't remember ever having any difficulties with it. i think it was about the size of the 5 cu ft -- obviously a different trailer, but I would expect that the frig should work well in the Escape without having to think all that much about it or to do things like replace plywood. Not every owner is that handy.

[Jim Bennett]

We have never had any trouble with the fridge keeping cold enough, though the hottest we have ever operated it in was about 36°C (97°F) for a couple day. but this was daytime highs, and nights did get down below 20°C.

[Parker]

Originally Posted by hotfishtacos

Parker, I explored probably every option to get the most out of the cooling system in my similar (but smaller) refrigerator and the changes that had the greatest impact on cooling were making sure the gas pressure in the low pressure system was up to spec...mine was too low so I adjusted it upward increasing the size and temperature of the burner flame...and improving the baffle behind the unit by removing the plywood baffle and installing a "Reflectex" baffle that I made which effectively covered the back of the refrigerator going up beyond the top coils. It included an angled baffle at the bottom. This change forces the air up through the coil system, avoiding the dead space area behind the refrigerator. BTW, your refrigerator has two fans mounted to the back just below the top coils. It comes standard that way. If the temperature gets high enough the fans will come on automatically. They are connected to a sensor switch on the top coils.

Hi Steve,

While we were camped at Lake Tahoe on the way home, I hit the local Ace Hardware and made a water manometer and discovered the propane pressure was only about 9". After confirming with Tammy that I should be seeing 11" (at the stove) I cranked it up. The Dometic manual lists 13.5" as the maximum allowable. What sort of pressure are you running? Maybe I should measure it right at the fridge.

I'm leaning toward a Reflectrix liner and baffle of some sort as well, unless I make some other discovery in the meantime.

I'll have to have a look tomorrow with a mirror and flashlight...I want to see those fans! I checked the electrical schematic for this model fridge and didn't find anything. They are installed by Dometic for certain installations with the upper vent on the side.

Thanks for your helpful comments.
Parker

[Parker]

Originally Posted by cpaharley2008

Parker,
Does your 19' have the roof or side mounted exhaust?. My 19' had the side mounted and smaller Dometic 3.0 and although it operated fine, there was a lot of dead air space. I inquired about the new refer in the 21' and was told that it fits like a glove and the walls are insulated and dead air space eliminated.

Ours has the roof mounted exhaust. Unless someone jumps in here to tell me they've had it off and looked around in there, I think I'll remove it tomorrow and check out the upper side of the fridge. If I end up installing some sort of baffle, I think it would probably be easier to do it with access from above.

The outer fiberglass wall isn't insulated, and there is quite a bit of space between the back of the fridge and the wall....both areas I may be able to improve.

[hotfishtacos]

Originally Posted by Parker

Hi Steve,

While we were camped at Lake Tahoe on the way home, I hit the local Ace Hardware and made a water manometer and discovered the propane pressure was only about 9". After confirming with Tammy that I should be seeing 11" (at the stove) I cranked it up. The Dometic manual lists 13.5" as the maximum allowable. What sort of pressure are you running? Maybe I should measure it right at the fridge.

I'm leaning toward a Reflectrix liner and baffle of some sort as well, unless I make some other discovery in the meantime.

I'll have to have a look tomorrow with a mirror and flashlight...I want to see those fans! I checked the electrical schematic for this model fridge and didn't find anything. They are installed by Dometic for certain installations with the upper vent on the side.

Thanks for your helpful comments.
Parker

My pressure was also at 9 so I raised it to 11.5. It doesn't sound like much change but it is almost 28% increase in pressure. The fan are there. I verified this....but I also have never heard them run so I hard wired them to a switch inside in case I ever wanted to run them manually. During my experiments after I built my baffle, running the fan made no difference...even during 95 degree F weather. I'm sure you have the roof vented exhaust because it is a tall refrigerator.

[rvomaha]

We're the ones who started the thread, referred to above, titled "Refrigerator not cooling on the road." Ours has always cooled fine when the camper is stationary, but cools poorly, if at all, during warm weather if the camper is in motion. First we tried installing a baffle between the camper wall and the coils, trying to mimic the installation in the Dometic manual. This made no difference. Then, after they conferred with Dometic, a Dometic service center installed a fan behind the top grill (wall-type grill). So far it appears that this has made no difference. --Jay & Liz

[hotfishtacos]

Liz, did you put an air baffle on the air inlet grill? This is standard practice if you don't want the propane flame to go out while traveling. When traveling do you use propane or 12Volts or is it off....and have you checked your gas pressure?

[rvomaha]

To answer you, hotfishtacos,

The propane flame definitely stays on while traveling and that is not the problem. I have ridden in the trailer under tow more than once to verify this. The baffle we installed is shown in one of the entries on our blog if you want to see it, but we removed that baffle when it didn't improve things. After that the new fan went in as the next big experiment. Subsequently, on a big trip in colder weather, the fridge cooled fine, even on the road. But on the latest tow, done specifically to test the refrigerator on an 84-degree day, the fridge temp went up significantly in about a half hour of towing.

While traveling we use propane for the fridge. We're going to pursue this whole thing further with the Dometic service center when we get back from an upcoming big trip. I can't answer you about gas pressure. I'm out of my element on that one.

--Liz

[cpaharley2008]

The outer fiberglass wall isn't insulated, and there is quite a bit of space between the back of the fridge and the wall....both areas I may be able to improve.
I'm going to follow up with Escape on this, I asked specifically about this because of winter camping I felt a lot of cold air intrusion back there.

[Parker]

Originally Posted by cpaharley2008

The outer fiberglass wall isn't insulated, and there is quite a bit of space between the back of the fridge and the wall....both areas I may be able to improve.
I'm going to follow up with Escape on this, I asked specifically about this because of winter camping I felt a lot of cold air intrusion back there.

Just to clarify, there is indeed several inches between the back of the fridge and the outer, uninsulated fiberglass wall of the Escape. However, I don't see the connection between this and air cold air coming in during winter camping. This entire area is vented to the outside, so the temperature in there is always going to be very close to whatever is outside. I am considering insulating it so the sun doesn't heat it up so much in there, which detracts from fridge performance on hot days. If you're getting cold air intrusion into the living area of the camper, that sounds more like an issue with the seal around the fridge itself.

[cpaharley2008]

True, and upon retrospect Reace did say the area around the refer itself was insulated, meaning little cold air intrusion into the living space was happening.

[Kountrykamper]

This is what we use at work

Yellow Jacket 78060 Gas Pressure Test Kit HVAC NEW [Misc.]: Amazon.com: Home Improvement

Allows you to measure it at the appliance. I would set it at 11.5". The .5" can make a big difference.

[Parker]

Originally Posted by Kountrykamper

This is what we use at work

Yellow Jacket 78060 Gas Pressure Test Kit HVAC NEW [Misc.]: Amazon.com: Home Improvement

Allows you to measure it at the appliance. I would set it at 11.5". The .5" can make a big difference.

That looks like a really nice unit, although I'm pretty attached to my water U-tube. Bring it along to the next Eggscursion and we'll compare. I probably should check it right at the fridge, though.

[hotfishtacos]

Originally Posted by Parker

That looks like a really nice unit, although I'm pretty attached to my water U-tube. Bring it along to the next Eggscursion and we'll compare. I probably should check it right at the fridge, though.

I also use a home-made Manometer to test gas pressure. It is easy to test system pressure it at the low pressure quick-disconnect outside near the door. The whole system will be at the same pressure when everything is turned off. It is interesting to turn on the stove burners or the refrigerator and watch the pressure drop.

[Kountrykamper]

Do the directions say to check standing pressure or running pressure?