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-   -   Simple Survey on Fridge Performance While on Propane (http://www.airforums.com/forums/f404/simple-survey-on-fridge-performance-while-on-propane-169937.html)

Joe Wezensky 07-18-2017 12:59 PM

Refrigerator problem
 
Prior to taking my BC to the dealer for installation of anti-sway device, we were on shore power and the lower portion of the ref never got below 52 Deg. When I got back home the ref temp was up to 84 Deg. I guess propane is not working.

Bborzell 07-18-2017 03:37 PM

Quote:

Originally Posted by Joe Wezensky (Post 1979700)
Prior to taking my BC to the dealer for installation of anti-sway device, we were on shore power and the lower portion of the ref never got below 52 Deg. When I got back home the ref temp was up to 84 Deg. I guess propane is not working.

I'm beginning to question my original thought about this issue being primarily a propane matter.

I switched to shore power at 7 pm last night. By 10:30 pm the freezer was 3 degrees and the box was 46 an improvement of 10 degrees of cooling since I switched from propane to AC at 7 pm certainly a move in the right direction.

By 7 am, the freezer was -8.5 (yes, minus) and the box was 26.8, but the outside temp was only 72.

I immediately switched back to propane because I wanted to approximate how much driving time I could get on propane before the box moved into unsafe food land.

By noon, the freezer was 2.8 and the box was 34.1. Clearly both the freezer and the box were warming up. But, maybe the warming would be happening whether on 120V or propane.

Since I had a sense that 6 or 7 hours was about tops for even a fridge that had been cooled to max and then shut off, I decided to go back to 120V and see if there was better cooling to be had during the heat of the day.

Stay tuned...

overlander63 07-18-2017 04:04 PM

Quote:

Originally Posted by Bborzell (Post 1979585)
Are you interested primarily in hearing from folks who have not added fans and or insulation? Also,are you are looking for data from propane operation?

All versions, so we can see what makes the most improvement. On the two we've done, temps dropped by 10 degrees when the cover was removed. I want to see if it's repeatable before offering a fix.

Gail Miller 07-18-2017 05:05 PM

Quote:

Originally Posted by RandyNH (Post 1979594)
So long as your power can support it, a DC compressor fridge is the best way to go IMHO, I pulled out the Dometic 3 way and put in a NovaKool, The inside temp is a steady 34 and 10 and had only fluctuated 2-3 degrees from that, with outside temps in mid 90s and high humidity.

One other benefit is that I also closed off the external vents and installed 5 layers of foil insulation on the back wall, keeping external air and temps outside, all needed ventilation airflow is inside, front floor level intake and top level exhaust, this way the coolest air inside is drawn across the heat exchanger on the back, two ultra quiet low power DC fans turn on whenever the compressor runs. This model draws 4.3A whenever it runs and uses 23AH hours overnight before the sun gets to work recharging the system.

The "heat" generated by the all inside setup is virtually none, the difference is 3-5 as measured.

Randy, what model # NovaKool did you get? I noticed in my Dometic installation manual some Dometics have temperature settings, the RM2351, which we have in our Basecamps is 'set at the factory' .... possibly a factory in Antarctica :-)

Xrad13 07-18-2017 05:22 PM

Thermistor adjustment
 
Perhaps I missed something, but I did not see mention of thermistor adjustment. Has everyone pushed the thermistor upwards to increase cooling?

Here is a video link if I'm not being clear.
https://www.youtube.com/watch?v=n6ZYmTanteQ

overlander63 07-18-2017 07:13 PM

Quote:

Originally Posted by Xrad13 (Post 1979870)
Perhaps I missed something, but I did not see mention of thermistor adjustment. Has everyone pushed the thermistor upwards to increase cooling?

Here is a video link if I'm not being clear.
https://www.youtube.com/watch?v=n6ZYmTanteQ

The problem seems to be a lack of ventilation causing poor cooling, not an adjstment.

Gail Miller 07-18-2017 07:14 PM

Quote:

Originally Posted by Xrad13 (Post 1979870)
Perhaps I missed something, but I did not see mention of thermistor adjustment. Has everyone pushed the thermistor upwards to increase cooling?

Here is a video link if I'm not being clear.
https://www.youtube.com/watch?v=n6ZYmTanteQ

Yep, I tried it ... in several different positions. I even tried it on a different fin. Made no difference!!!! I can't remember now where I saw something about it.

RandyNH 07-18-2017 07:37 PM

Quote:

Originally Posted by Gail Miller (Post 1979860)
Randy, what model # NovaKool did you get? I noticed in my Dometic installation manual some Dometics have temperature settings, the RM2351, which we have in our Basecamps is 'set at the factory' .... possibly a factory in Antarctica :-)

Gail, I removed a Dometic 2454 and replaced with a NovaKool 5810. The Dometic had a button on the front with 5 setting levels, the NovaKool has a knob inside from 0 to 7 (0 actual turns it off completely) the temps mentioned are at 4.25

These are slightly larger than the Basecamp model, but still the single box system with the little freezer section above, I believe the amp draw in your size unit is half of mine

Your comparable NovaKool would be an R4500 which is a 4.3 cu.ft.

Gail Miller 07-18-2017 08:08 PM

Quote:

Originally Posted by RandyNH (Post 1979943)
Gail, I removed a Dometic 2454 and replaced with a NovaKool 5810. The Dometic had a button on the front with 5 setting levels, the NovaKool has a knob inside from 0 to 7 (0 actual turns it off completely) the temps mentioned are at 4.25

These are slightly larger than the Basecamp model, but still the single box system with the little freezer section above, I believe the amp draw in your size unit is half of mine

Your comparable NovaKool would be an R4500 which is a 4.3 cu.ft.

Thank you!

Bborzell 07-19-2017 12:47 AM

Quote:

Originally Posted by Xrad13 (Post 1979870)
Perhaps I missed something, but I did not see mention of thermistor adjustment. Has everyone pushed the thermistor upwards to increase cooling?

Here is a video link if I'm not being clear.
https://www.youtube.com/watch?v=n6ZYmTanteQ

A thermister adjustment was a part of the dealer fan install. Didn't help.

InterBlog 07-19-2017 07:06 AM

Forgive me if I missed this, someone else may have posted it, but here (PDF link) is the link to the Dometic Diagnostic Service Manual for these fridges.

Among other things, it gives information on how to test the function by basically running it wide open (bypassing the thermostat for continuous operation).

There is an ominous statement on page 24: "A refer (sic) that chases (sic) the out-side temperature is improperly vented or has a weak cooling unit."

We knew that our venting was the best that could be achieved, so the default conclusion is that its cooling unit was "weak". The term was not described in the manual, nor was there any explanation of how a cooling unit might become "weak", nor were there any suggestions on how to fix "weak". Given that the cooling units are integrated and have no moving parts, presumably the only option is wholesale replacement.

One of the other posters in the thread above above appeared to have a chaser - a fridge that followed ambient temperature - which is why I mention that.

Also, this other recent thread called Two-Way Refrigerator throws out some other information that y'all might find interesting as you continue your investigations. It deals with Airstream Interstates, but Interstates take the same sized fridge as Base Camps, whether it's Dometic or some other brand. One of the interesting claims to fall out of that thread is that Norcold refrigerators are currently failing at a rate of 80%, according to one distributor who was quoted. So, if any of you ultimately decide to ditch the Dometic, do your homework on replacement options.

Bborzell 07-19-2017 09:07 AM

Quote:

Originally Posted by InterBlog (Post 1980079)
Forgive me if I missed this, someone else may have posted it, but here (PDF link) is the link to the Dometic Diagnostic Service Manual for these fridges.

Among other things, it gives information on how to test the function by basically running it wide open (bypassing the thermostat for continuous operation).

There is an ominous statement on page 24: "A refer (sic) that chases (sic) the out-side temperature is improperly vented or has a weak cooling unit."

We knew that our venting was the best that could be achieved, so the default conclusion is that its cooling unit was "weak". The term was not described in the manual, nor was there any explanation of how a cooling unit might become "weak", nor were there any suggestions on how to fix "weak". Given that the cooling units are integrated and have no moving parts, presumably the only option is wholesale replacement.

One of the other posters in the thread above above appeared to have a chaser - a fridge that followed ambient temperature - which is why I mention that.

Also, this other recent thread called Two-Way Refrigerator throws out some other information that y'all might find interesting as you continue your investigations. It deals with Airstream Interstates, but Interstates take the same sized fridge as Base Camps, whether it's Dometic or some other brand. One of the interesting claims to fall out of that thread is that Norcold refrigerators are currently failing at a rate of 80%, according to one distributor who was quoted. So, if any of you ultimately decide to ditch the Dometic, do your homework on replacement options.

What is particularly interesting to me is that as the fridge appears to be "chasing the outside" temperature, the countertop directly over the fridge gets hot. That strongly suggests to me that lack of adequate venting is the issue.

I'd like to hear from folks who are having cooling problems on 120V. Is the lack of cooling accompanied by a hot countertop?

Bborzell 07-19-2017 09:18 AM

Speaking of chasing outside temperature, I just rechecked the fridge after all night on propane.

Outside temp: 66
Freezer: -7
Box: 25.4

It will get into the high 80s-low 90s today. I'll keep on checking.

MrKenmore 07-19-2017 11:20 AM

So we called Airstream and spoke to John:

-The issue is currently with production

-No Service Bulletin Has been issues

-It may come out in the near future

-Solution is to improve the ventilation

- We may want to contact our local dometic dealer to make sure it is not the fridge

- Someone will contact us if there is a service bulletin issued.

Bborzell 07-20-2017 09:48 AM

This morning the freezer was at -7 and the box at 28 degrees with an outside temp of 64.

The pattern on propane is pretty clear. When the outside temp is around 70 or below, the fridge works fine. As soon as the temp rises to 85 or so, it gets overwhelmed by buildup of heat in the cabinet and the freezer gains 20 or so degrees as does the main box. After two days on propane, the box continues to increase to between 6 and 10 degrees above the minimum 40 degrees needed for food safety.

Since our trip to from northern California to Charleston, SC will be along US40 (not exactly cool temps), we will rely on a 30 qt. Pelican cooler for drinks and snacks and eat out alot. The second leg will take us to within 125 or so miles of the Airstream factory. We are hopeful that Airstream engineers will have devised a fix by the time we are in their area (probably the 28th) that adequately removes heat from the cabinet and does not rely on the extremely loud fans that they are currently recommending. There are many silent fans available that would accomplish needed venting while not introducing unnecessary noise. As it is now, I can hear the fans while standing 70 feet away from the trailer and they run constantly. I am anticipating hearing complaints from campground neighbors.

Troutboy 07-20-2017 05:17 PM

My three fan mod cost $60. Can't here the fans inside the trailer. I still believe it's an airflow issues, having the right fans as well as making sure air flows over the coils optimally to remove the heat. Should be the same for the basecamp space.

OTRA15 07-27-2017 05:26 AM

Quote:

Originally Posted by Troutboy (Post 1980801)
My three fan mod cost $60. Can't here the fans inside the trailer. I still believe it's an airflow issues, having the right fans as well as making sure air flows over the coils optimally to remove the heat. Should be the same for the basecamp space.

You are being optimistic IMO, and have not examined the problem closely, in terms of the BC fridge exhaust vent being about an inch away from the back of the propane cover. With no room for the exhaust air to flow freely, it is stifled, and the hot air stays trapped, stagnant in the cabinet space. ESPECIALLY if the front of the trailer is in direct sun.

With your design and fabrication skills, in my opinion you would appreciate this if you examined the problem more closely.

The Basecamp Issues thread has more details on the fridge problem as well.

No quick and easy fix here, again in my opinion, short of a substantial redesign of the layout of the components they are trying to JAM so close to each other. Also, Dometic's design parameters seem to conflict with the fridge's layout and venting system IMO.

Peter

PS see Post #600 et seq. on the Issues thread:

[click on arrow in quote to go there]
Quote:

Originally Posted by OTRA15 (Post 1977924)
Is there an air gap between the front of the trailer, and the propane cover as shown here? Looks like a mighty small space IMO. Even with fan assist, moving hot air out of the way quickly is going to be challenging if this end of the trailer is in direct sun on a hot day!

How about a dedicated mini-awning which can deploy to put the front of the trailer in shade? There could be a sun-sensitive switch which triggers this, like the rain sensors on the rooftop fans.

:blink:

Good luck,

Peter

https://www.airstream.com/wp-content...ation_Unit.png


RandyNH 07-27-2017 06:04 AM

At this point, someone with design and fabrication ability needs to create a channel from the exhaust port to the top of the propane cover, install a vent cover in the propane cover and leave a gap between the channel and body of the trailer, so that water can drain that might get in the top of it. This way the air exhausted from the fridge can clear the area of the propane tanks.

Is there enough space between the top of the tank area and the cover for such a channel?

Rzr1999 07-27-2017 10:28 AM

Proper flow for cooling
 
1 Attachment(s)
I believe this is the proper chimney for air flow

uncle_bob 07-27-2017 11:07 AM

Hi

Here's yet another problem / question to toss into the pile:

When moving, air flows over the TV. It then hits the front of the Basecamp. My guess is that it flows *down* over the front of the trailer in the area between the propane tank cover and the trailer. It then exits under the trailer. (= high pressure just above the propane tank cover). A "tall" TV would create a different pattern than something like a sedan hatchback. Yes, with a big automotive wind tunnel or a copy of FloEFD you could dig further into this.

If the air *is* doing this, pulling the trailer is actually *worse* than having it sit stationary in the driveway. Even with fans, you have a limited back pressure range. At some point, the air simply stops moving. It's not just an issue if you are relying on convection.

Bob


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