Fridge cooling: coils or fins?

[Gerald55]

I'm making an extended trip into a hot area, and often my Dometic fridge does not cool adequately. It has no fans at the back to help cooling, and so I'm adding 4 thermostat controlled fans, as well as some baffling, to help.

What is unclear to me is exactly what needs to be cooled. Many posts simply refer to "the coils" - but there are at two things which seem like they could use additional cooling:


1) The condenser at the top of the fridge. This is a set of heatsink fits on the pipe right after it comes out of the boiler.

2) The absorber. This is a set of large turns of the pipe forming coils, lower down (just above the tank-like absorber vessel at the bottom of the fridge).

The absorber better fits the definition of "coils", but the condenser obviously seems like it needs to be cooled as it is heavily finned and is the hottest part of the fridge based on my non scientific tests.

I can't figure out how to attach pictures (from mobile), but I'm working on it.

[Gerald55]

Chris Bryant wrote:
The top condensor fins are the most critical. The more liquid ammonia you can condense out the more cooling you will have. The absorber coils do reject some heat, but that is not their real function.

The unit should be baffled so that all of the air must pass over the condensor.

Thanks! My fridge does have baffling, but it is focused on the absorber and stops before the condenser fins, so air can indeed avoid the absorber unit. I'll fix that.

[dougrainer]

pianotuna wrote:
Hi,

I got more benefit from dual fans inside the fridge than from cooling the outside stack. I chose to use a vent mount just under the rain cap. I made a mask to restrict help flow in the winter time. The twin computer fans are thermostatically controlled.

I do have the ARP unit to help prevent overheating. It has been a great relief to me.

Fans inside and outside will help dramatically. As to how many fans on the outside, you only need 2 fans max blowing UP. Have them BELOW the condenser fins blowing up. As Chris stated, you need to make sure (OEM's rarely get this correct) the space between the fins and the sidewall is blocked off to force all the cool air thru the fins. Now, if refer in a slide room, you need another modification. Add 1 fan at the top blowing OUT the upper access door. to help remove the HOT air that has just passed the Condensor fins. THIS fan is critical even of you have the fans below the condenser. Most OEM's do not install this top fan on slide out installs. So, if you already have fans on a slide install, add this extra fan. Now, to fans inside the refer. The refer operates inside by convection air flowing upward along the back wall up thru the Evap fins (which removes the heat) and over and down in a continuous circle cycle. With Plastic tubs and Freezer type bags being used now, people OVERPACK the bottom of the refer and restrict this air flow and rear 1 inch space needed. Having that rear 1 inch space will make the refer cool much better. But, adding the inside fans will help tremendously because people will always block that cycle of air. Doug

[dougrainer]

grizzzman wrote:

Chris Bryant wrote:
The top condensor fins are the most critical. The more liquid ammonia you can condense out the more cooling you will have. The absorber coils do reject some heat, but that is not their real function.

The unit should be baffled so that all of the air must pass over the condensor.

Chris what is you're opinion on the ADP system?

The ARP system is a GOOD addition to any RV refer. It keeps you from damaging when run either off level or if you get a ventilation blockage. Doug

[grizzzman]

Chris Bryant wrote:
The top condensor fins are the most critical. The more liquid ammonia you can condense out the more cooling you will have. The absorber coils do reject some heat, but that is not their real function.

The unit should be baffled so that all of the air must pass over the condensor.

Chris what is you're opinion on the ADP system?

[Chris_Bryant]

The top condensor fins are the most critical. The more liquid ammonia you can condense out the more cooling you will have. The absorber coils do reject some heat, but that is not their real function.

The unit should be baffled so that all of the air must pass over the condensor.

[pianotuna]

Hi,

I got more benefit from dual fans inside the fridge than from cooling the outside stack. I chose to use a vent mount just under the rain cap. I made a mask to restrict help flow in the winter time. The twin computer fans are thermostatically controlled.

I do have the ARP unit to help prevent overheating. It has been a great relief to me.

[2oldman]

Seen this?

youtube.. rv refer vent fan

[Gerald55]

Right, I'm planning on using all four fans to promote a good bottom to top flow, two in-between the vents, and two on the top vent to expel the hot air.

I still kind of need to know what need to be cooled though, since it affects fan placement and baffling. In particular, the condenser fins at the top are poorly barffled and tend to be hot because they are located right at the top of the top vent. Fixing that requires some work. Work I want to avoid if what needs to be cooled is the condenser coils.

[Gerald55]

The condenser (aka thing 1) is like this:



The absorber coils are something like this (different color though):

[downtheroad]

The key is to move air UP from the bottom or suck air UP from the top. Either, or both.



It also helps to move air around inside the box itself by putting a fan or two on the inside fins.



Or::::you can get real creative like this guy. (it's not me)

[2oldman]

From what I read, all of it should be cooled as much as possible.