I have always enjoyed your posts, and the pics of your work.
A moderator must have cleaned up my different fonts off the two laptops I was using.
(Thanks moderator)
Harry
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Harry, that was a wonderfully detailed post. I know how much mental energy and time it takes to put that sort of thing together . . . thanks for taking the time and expending the energy.
I'm not Harry (and can't even come close to his advice - by about four orders of magnitude), but I still think you'd want both of those fans exhausting air (vs. the way you have it with one drawing in and one exhausting).
That's because I think you want the fact that the fans are pulling hot air up and out (both of them) to be what makes cold air come in at the bottom.
With them one going each way, and both at the top, I don't see any "reason" that cool air would want to come in at the bottom (not to anthropomorphize cool air...). It seems like your current way would just make for a little enclosed loop at the top, with the bottom all left out and lonely.
I personally use foil backed engine firewall spun fiberglass heat shield, its spun fiberglass tightly compacted that has a foil reflective barrier...This is a personal thing I do, B-Wrap is fine, the reason I use the other is IF I ever had a fire, the spun fiberglass would contain the fire longer and allow me to get a fire extinguisher.
Happy Camping, Safe Trails.
[b]I should not be crowned Raya, I am bored stiff...
I go to surgery Tuesday the 20th and your wonderful question keeps me sane...
I would rather be camping!!!
If not that I will natter.
Harry
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[My new text is in green so that I can put stuff in between Robert's quotes, and not have it all confusing.]
I love engineers, and they do great things, but one should never underestimate real-world experience. Thank you!
Quick question: Would something like that metallic/air-bubble insulation be an example of a good infrared barrier sheet? If not, then can you name an example?
I hope you're up and about and camping ASAP after your surgery Your out-of-the-way-place camping reports are great, too
Until then, if you really are bored, can you explain what you meant by properly sized vents? Real-world, the Bolers are pretty limited (unless one were to put in a chimney/pipe), but I do notice they usually have a larger vent at the bottom (Dometic) and then a smaller one up top (either just below or just above the belly band).
Is the larger/lower smaller/upper the right general idea?
Trailer: 1972 Boler American and 1979 Trillium 4500
Posts: 5,141
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you need to understand you can [b]PULL more air thru the compartment than you can push with the same size fan fan.
Harry,
Thanks for that comment. You've made up my mind on how to add my fans. My fridge has a small fan built in at the bottom that needs replacing. It is controlled by a thermocouple attached to the fins. You can see it in the picture I posted earlier connected to the blue and yellow wires: http://www.fiberglassrv.com/board/index.ph...st&id=17779
I'll disconnect the original fan and use that wiring for the computer fans in the upper compartment. I remember reading somewhere that if one connects the fans in series they run slower and draw less power. But that was in reference to the larger 12V computer case cooling fans. Any thoughts on that, with respect to both power and cooling efficiency?
Best wishes for your health.
Roger,
If you look at the picture (link above) you'll see how much room you have for vents above the belly band. You've got about an inch less in height from the rivets for the lower kitchen cabinet.
As a reference, check out the photo of my vent set-up on my Scamp.
These vents are the ones spec'd by Dometic to fit the small 1.9cuin 2190 model that I have. You can see that the upper vent isn't that much smaller than the lower. I was able to keep the upper vent below my belly band and still keep it positioned slightly above my fridge cooling fins.
Where is the top of the uppermost fins? In my case it was above the pre-existing vent, that is why I moved the upper vent to above the belly band and the top of the uppermost fins.
Roy,
Since the fridge install was recent, I was able to put my venting exactly where I felt they should go. My cooling fins are just a couple inches below the top of the fridge (approx. 22" off the floor). They are also centered behind my upper vent. (See bellow.)
As a reference, check out the photo of my vent set-up on my Scamp.
These vents are the ones spec'd by Dometic to fit the small 1.9cuin 2190 model that I have.
Hi Robert,
Thant looks similar to the vent set-up for my Dometic fridge too, and is what's on my Boler. I was just curious about Harry's take on it, since he's got Real World experience that may or may not agree with what the manufacturer suggested.
These crappy fridges can't cool anything if its over 90 degrees especially after the flame blows out on the hiway.
Bring an ice chest and don't expect too much even if it has a fan.
These Dometics have many problems-feeble door latch-flame out-need interior and external venting-worthless 12V cooling to name the worst.
Sorry to be so negative but that's reality.
Nothing wrong with reality, but others seem to have good experiences with their Dometic 3-way fridges. I'm sure they are challenged when it's over 90 degrees though. I'm just curious: Does yours also have problems cooling in that hot weather if it is plugged in to shore power (I realize it uses the same cooling mechanism then)?
Also, I think they mean for you to run it via 12v connection when you are underway, if I'm not mistaken.
I suppose a "regular" electric fridge, with a compressor (vs. absorption) would work better in really hot weather, but it's so nice to be able to run it on propane, and the silence is great too (in my opinion).
Has your installation been modified in the ways that Harry suggests? How much did that help compared to the stock installation?
Raya
PS: If you really do decide to get rid of it, please advertise it here, as I don't believe one can get parts for the original Dometics we had in our older eggs (2100 model, going by memory).
Nothing wrong with reality, but others seem to have good experiences with their Dometic 3-way fridges. I'm sure they are challenged when it's over 90 degrees though. I'm just curious: Does yours also have problems cooling in that hot weather if it is plugged in to shore power (I realize it uses the same cooling mechanism then)?
Also, I think they mean for you to run it via 12v connection when you are underway, if I'm not mistaken.
I suppose a "regular" electric fridge, with a compressor (vs. absorption) would work better in really hot weather, but it's so nice to be able to run it on propane, and the silence is great too (in my opinion).
Has your installation been modified in the ways that Harry suggests? How much did that help compared to the stock installation?
Raya
PS: If you really do decide to get rid of it, please advertise it here, as I don't believe one can get parts for the original Dometics we had in our older eggs (2100 model, going by memory).
I concur with Raya...
My first outing with my Scamprenovation, and new Dometic, was super.
I followed the advice of those here on the forum and pre-cooled my fridge with 120v before I left home. Then switched over to 12v for the four hour drive the the NOG we just put on here in Oregon. By the time I got to my camp site and unhitched, I found the beer nearly frozen! Shore power kept things cool for the duration. Of course, it wasn't 90 degrees, but I'm quite confident that the fridge will work as designed.
That said, and as you may have gathered from reading this thread, I did put a lot of thought into my entire fridge configuration, including the insulated shroud that reduces the effects (I'm told) of ambient heat.
My fridge is about 3 years old-freezer not included on new models.
Never does much on 12V even with a 10ga. wire. On 110 fairly well.
Has the little fan like promoted here.
I glued a 2 in. foam board under the trailer floor-maybe helped a little.
The basic problem is there is not enough insulation outside. But that would require more space.
Look at a household propane fridge-it is huge!
I've never read any discussion about the blowout problem.
I put in perforated aluminum behind the louvers openings-no help.
Now I'm trying pink wool wads stuffed in cracks in the flame area-not tested yet.
Yeah, the freezer is nice. Plus, the newer units are deeper, and stick out into the trailer.
On the perforated aluminum: It seems like the main issue with our units is getting the heat to exhaust (since what the fridge is really doing is removing heat). It gets out of the fridge but then has a hard time getting out of the trailer because we don't have "real" chimneys but only little vents.
I would think that perhaps the perforated aluminum is actually reducing airflow coming in (can't see it, so just postulating), further reducing the chimney/cooling.
I think if it were me, I would give up on using propane when driving, and would try to get the heat to more effectively transfer out of the surround.
Do you have two fans, as Harry suggested, and are they both at the top of the enclosure, and both exausting? It sounds like that is the way to go.
I wonder if there is a specific problem with your 12-volt operation, or if it is related to the general "hot air not exausting" issue?
On the older Dometics, they were not dual carb units, the new ones are so they are less sensitive to angles as the old generation, Norcold as well...
The pictures are great, in the ones I have seen I can see you are not using the Dometic access doors?...On the older trailers the louvers poke out so rain water sheds off it efficiently. The new design the louvers poke in forming scoops.
These older doors suck, they void warranties too.
There is an important design innovation to these side saddle mounted refrigerators that have come up the production line in the last decade.
It seems F.B.R.V. folks are not aware of it for what it is.
Its not just a new fancy door?
The new lower door design and matching new upper design uses an inside out scoop intrinsic to the doors venting system greatly improving heat transfer.
This is really important to the operation of side saddle mount installations.
I will try to post pics to this design at the bottom.
As hot condenser air rises in the new design doors a portion of the warm air is scooped up with the louvers from inside the space and thrown away.
The new louvers "cup" away air as it rises
Dometic requires this door vent system on all installations, it works much better than the old louvered door of old. As an installer I must upgrade to this system with each NEW install or void warranties.
Side saddle venting arrangements like I saw in the in the pics lock more heat into the compartments because the louver faces outward, maker the interior wall smooth to air.
Look at the pics, imagine you are hot air sliding and rising becoming lighter and lighter, looking at the new design ask yourself what happens to you when you brush up against the new design?
Those louvers are completely the opposite of what is on the older Bolers; it's exactly as you described.
For replacing the older louvers with the newer ones, is it more important to replace the bottom or the top or both? (I'm guessing based on what you said that the top one is more critical...)
I would do both, but if I had to choose the top is non negotiable, a must.
Harry
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That's interesting, Harry. Makes sense, too!
Those louvers are completely the opposite of what is on the older Bolers; it's exactly as you described.
For replacing the older louvers with the newer ones, is it more important to replace the bottom or the top or both? (I'm guessing based on what you said that the top one is more critical...)
I buy at eBay often, the lower door in this style opens, the top in this style stays closed when bought as the set...What I do is I use two lower doors so [b]BOTH open.
I like to be able to clean the upper compartment without disassembling the trailer!
Also I can service the small fan in mine at the top.
Happy Camping, Safe Trails.
Harry
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I'm definitely going to replace the top vent then. The bottom one is a nice one that opens, etc. but the top is nothing special so it's a no-brainer.
Are these Dometic brand vents? Or can you name a source?
Thanks - this is going to be a great reference thread!
Since it sounds like you've sourced quite a few refrigerator vents, I wonder if you know if it is possible to get metal ones? I went to look at the eBay ones you linked to, and I see that they are genuine Dometic, but I'm a bit hesitant to replace metal vents (that are still in good shape after 35 years) with plastic ones.
Now these may be a better plastic - and I see they can be painted - but in general I've been disappointed with RV plastic parts (such as the electrical cord access door that is completely degraded).
I'd like to get the new style vent for efficiency, but I'm going to try to find metal ones. If you know of a source, great. And/or if I find one, I'll post it here.
Trailer: 1972 Boler American and 1979 Trillium 4500
Posts: 5,141
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... fridges can't cool anything if its over 90 degrees
...worthless 12V cooling
...
Sorry to be so negative but that's reality.
FWIW
Mine now makes ice in the 90's on 120V and propane. The 12V is better suited to [b]maintain cooling while travelling. My fridge was designed to run on propane with a sealed combustion chamber with separate intake/exhaust vents. The propane works better than the 12V while travelling.
Maybe it's due to different models.
Who knows. I'm happy.
Roy
Your out-of-the-way-place camping reports are great, too 
Perris Pacer
Scamper
Trailswest Campster
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