Looking to install a fan to help Refer cooling

[mbubbaca]

Hi, I'm doing my research( on the general FS Forum there are several threads) and it seems that installing a fan ( computer type ) to help move hot air from the refrigerator outside access compartment would be a good thing to increase refer efficiency in hot weather. So to the group, has anyone done this on the 2000 safari? I've resourced a thermal switch that will close at 80 degrees. Any comments on a fan source? I've been on Amazon and see plenty of options. Any placement advice?

[rmkrum]

I'd suggest looking for a computer-type fan, as large a diameter as will fit in the opening, with either manual or temperature-sensing adjustable speed control. Look for as slow a speed as possible and multiple blades to keep the noise down.

Some have installed three fans in the door opening, and added switches to control how many fans are running. You need a baffle to make sure the air is going out the vents.

It's a delicate balance between moving enough air to keep the fridge cold enough, and maintaining sufficient peace and quiet inside the AS.

[mbubbaca]

Originally Posted by rmkrum

I'd suggest looking for a computer-type fan, as large a diameter as will fit in the opening, with either manual or temperature-sensing adjustable speed control. Look for as slow a speed as possible and multiple blades to keep the noise down.

Some have installed three fans in the door opening and added switches to control how many fans are running. You need a baffle to make sure the air is going out the vents.

It's a delicate balance between moving enough air to keep the fridge cold enough, and maintaining sufficient peace and quiet inside the AS.

Yes, I've selected a very quiet computer fan. I plan to put an override cut off switch to just stop the fan if the noise is too loud.
So you're thinking or know that there isn't a chimney function from the bottom to the roof. In other words, the vent on the roof doesn't vent the air from the outside access box and I'll need the baffle to direct the air out.
I was assuming ( I know a bad idea ) that if I added a fan to intake the air it would flow out the roof vent. Looks like another trip to the storage yard to look up the side or down from the top to see if there is a place for air to vent through the roof. Maybe the schematic for the plumbing will tell me if no one from the esteemed forum already has experience.

[rmkrum]

On my rig, the fridge is installed under the counter, and the outside has two vent doors, one at the bottom of the fridge, the other at the top. The fans go in the top door area, blowing hot air out.

If you only have ONE outside fridge access door, there should be a vent of some sort in the roof. In that case, put the fans in the bottom, blowing cool air in. In this case, the fridge MUST be fully sealed into the cabinet opening to avoid blowing combustion gasses from the burning propane into the interior of the Airstream around the fridge...add weatherstripping or caulk as needed.

[woodfox45]

On our last Airstream when we replaced our fridge the dealer installed a fan up in the top of the fridge under the coils with a thermostat that would come on automatically when it got hot it was a12volt computer type fan seemed to work good . Our current Airstream doesn't have a fan and cools fine it's the original fridge as far as I know .

[PaulnGina]

I cannot post any more pictures here, but if you don't mind reviewing my thread in our Avion forum, here is the link... maybe it'll give you some ideas. I especially like the thermostat that controls the fans. I would be glad to answer any questions.



http://www.aviontrailers.net/viewtopic.php?f=8&t=342

[mbubbaca]

Originally Posted by rmkrum

On my rig, the fridge is installed under the counter, and the outside has two vent doors, one at the bottom of the fridge, the other at the top. The fans go in the top door area, blowing hot air out.

If you only have ONE outside fridge access door, there should be a vent of some sort in the roof. In that case, put the fans in the bottom, blowing cool air in. In this case, the fridge MUST be fully sealed into the cabinet opening to avoid blowing combustion gasses from the burning propane into the interior of the Airstream around the fridge...add weatherstripping or caulk as needed.

It's advice like this to "seal the cabinet" that makes this forum so worthwhile. I plow through 100's of TV, Tire and TPMS conversations and find a gem like this one. Thanks.

[CruizinDux]

here is the long and winding road...
http://www.airforums.com/forums/f425...-11811-19.html


just remember that designs vary greatly. There are a lot of other "refer fan" threads. Just plug that into the search function at the top.

For me it was a 1 fan swap. Very easy. Just look at the specs for the replacement...flow and DB. Do you want better flow for cooling or do you want quieter? It's a trade off. Last comment, this is a project that can easily be over designed. You'd be amazed the effect of simply opening the top door.
Bob

[rowiebowie]

This is the button thermostat I used to power a 12v fan to vent my compressor fridge. Should work for your purposes.

It is 100 degree on/85 degree off thermostat https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1, .

[rmkrum]

Also, on the two access door setup, and possibly on others, there is supposed to be an angled sheet-metal baffle (about 3 inches wide) about mid-way up the fridge to make sure airflow goes through the fins and boiler section of the fridge. It's there to keep the airflow from bypassing the hot side cooling coils. The slightly higher end (about 1 to 1 1/2 inches) is on the side of the fridge that has the boiler tube assembly on it (the part that is heated by electric or gas to make the fridge cool).

On my 2007, from the factory, the baffle was about three inches wide thin galvanized sheet metal, was the full width of the compartment, and was stuck in place at the ends with a big sloppy glob of caulk. It promptly fell off shortly after we acquired the AS. My plan is to use the old one as a template to cut a longer piece of metal with added tabs on the ends, and screw those tabs into the fridge cabinet sides--like it should have been done originally...

It's one of the very few design/build quality and possible QA-related issues left on our AS that is still bugging me...

[GM Airstream]

I did it to mine.... I too have pix and drawings of the fan mounts... but because of the issue of limited pix space... can't post them.

I have the dometic refrig... and they put out a pub on the installation of the ref fans and location as to where to put the thermal switch. go on the web and look up

http://bryantrv.com/docs2/temp/powervent.pdf
POWER VENTILATOR ASSEMBLY
For Two Door Absorption Refrigerators

I made up my own sheet metal brackets... and found that two of the 4 inch computer fans were good enough for mine. I wired the fans so I can select 1, 2 or shut them off...while the common side is going through the thermal switch or I can bypass it.

I used two of the single pole double throw mini toggle switches.. that we got at FRY's electronics. along with the muffin fans... look for the ones that are quiet, high flow and low current.

I made the a second bracket down at the bottom of the refrig so that its a neat location for just open the access door and you have the switches and fuse right their... oh ya make sure you fuse the two fans through the common lead. Just in case you get a short... its protected.

While we had the refrig out of the hole... (replaced the cooling unit also also) we also put some fiberglass around the refrig where A/S or others leave a large open space. The top of the refrig got really warm when on propane... and was require'n the cooling to work harder. With the fiber in their... it now feels cool on the top cabnet bulkhead instead of warm without it... I think it also helped the refrig along the sides too...

As now...

My refrig keeps the 38 deg even when it gets to 95 deg air temp.. and sun beating on the side of the A/S. I thought that the fans would run all the time... and that they really only come on every so often... due to the thermal switch.

I did some testing on hot days.. and found that unless its extreamly warm on the hull... the fans do not run.. the refrig stays cooler and so doesn't have to work as hard and long now that we put the insulation in. The addition of the two fans... gives a good draft...to move air not only over the condenser but also through the vent space and out the top... I would not think that anything more than 2 fans... would only add to the noise and current demand.. without not much advantage or effecency.

As to noise... I leave the switch on just one fan... and can just barely hear it when it total quiet inside the trailer. Putting both on does have some interaction between fans... and sound like a twin aircraft prop... but again you really have to strain to hear it run... when it does.. but so far they have not been needed... and we leave them in the off position... (the stock thermostat is set for 150 closing and 130 deg opening)

I have forced the fans on by bypass'n the thermostat... and not noticed much different in the inside temp... but, I am told that once you get to over 100 deg air temp... when the refrig is working... it will cause the fan/fans to come on... and blow against the top condenser fins... Located at the top of the refrig... blowing air anywhere else in the compartment.. according to dometic... is not effective...

If you look at the pub that they put out.. you can see they have a compartment fan located down at the bottom... here the engineer said that its to help keep the compartment somewhat cooler.. but that the condenser is the primary consern you want to cool...

I made my brackets for the fans out of galv sheet steel.. and sheered and bent it on my shop equip... I would send the cad cam drawings here for all to get ideas or copy but.. again.. the blog is limited and not wanting to waist its space... (they need to work on this if they want to have a good library of DYI.

G.m> WA6CDE

[mbubbaca]

Thanks for the suggestion and the Avion thread. So you up the fan assembly way up in the chimney? Is that right?
I got concerned with the comment about pushing gas into the trailer if the fan was mounted low in the compartment.
It would seem that if the fan were placed above the gas intake/exchange/whatever and still could move air over the coils, we'd be good.
I'll be mounting everything on the outside in the refer access space. There seems to be power near enough. My only challenge will be getting the fan placed. Trade-offs of space, access and how contorted I'll need to get.
I'm probably over thinking and should just hang a fan inside and move on. FYI:
I purchased a thermo switch from Senasys a USA source. They were very helpful with suggestions and anytime I can buy USA I do. I'm currently scrounging around my computer geek friends for a fan, if not, there are plenty on Amazon.

[SeeMore]

There are many ways to use Silenx computer fans to boost cooling. Air movement is best on the "outbound" side of the blades and when mounted close to the heat transfer fins are extremely efficient. I used four 2" fans wired in parallel that produce almost no noise whatsoever and included both a temperature sensing on/off switch and manual override switch in the circuitry. Installing a baffle is not necessary with this approach. In addition, an active fan circuit is not necessary when temperatures drop below 80 degrees ambient. Mounted adjacent to the fins, it is sufficient for 'chimney's which utilize the side door ingress and roof exhaust elements (pic):

http://www.airforums.com/forums/f425...ml#post1320168

The smaller, dual door cavity designs typically use the hatch booster fan approach (pic):

http://www.airforums.com/forums/f425...ml#post2086775

[PaulnGina]

Originally Posted by mbubbaca

Thanks for the suggestion and the Avion thread. So you up the fan assembly way up in the chimney? Is that right? ......

You're welcome, and yes, I mounted mine near the top of the chimney. It was easy on ours after I removed the cover that is above the vent on the roof.