refrigerator drain check valve

Dave H M wrote:
In my decades of RVing, I have never heard of a P trap in the frige drain.

I have never seen a difference with the frige performance with or without the plug.

It usually does not make a difference when camped. But, in transit, the refer can actually pull outside air up into the refer. Ideally, you want the P trap to make the refer the most efficient. The install manuals do not state to do this, it is just a good idea to do to make the refer more efficient. I believe Dometic feels the end plug small holes help stop air intrusion. Doug

In my decades of RVing, I have never heard of a P trap in the frige drain.

I have never seen a difference with the frige performance with or without the plug.

fpresto wrote:
There is a common misconception about that plug. It is not a check valve but rather a debris/insect screen. I have 4 spares right now and can assure you that you can blow through either side.
However, as the drain line has a straight shot from inside the refrigerator to the outside you will lose cold air out the tube if it, the drain tube, is installed wrong. I have read up to 11 degrees. The correct installation goes down and then back up exiting at the top of the access panel. This forms a loop kind of like a "P'-trap. When the loop fills with water that then blocks the cool air from escaping. Ford's RV and Training Service has an excellent series of videos on RV refrigerator repair and misdiagnoses. I highly recommend watching them all. This link goes to #3 which discusses the drain. Link

Very Good. I have probably seen just a handful of Dometic drain tubes installed correctly with the P trap loop in 25 years. The OEM's NEVER install the drain tube correctly, they just route it out the lower access door. NORCOLD refers have a real check valve. Doug

There is a common misconception about that plug. It is not a check valve but rather a debris/insect screen. I have 4 spares right now and can assure you that you can blow through either side.
However, as the drain line has a straight shot from inside the refrigerator to the outside you will lose cold air out the tube if it, the drain tube, is installed wrong. I have read up to 11 degrees. The correct installation goes down and then back up exiting at the top of the access panel. This forms a loop kind of like a "P'-trap. When the loop fills with water that then blocks the cool air from escaping. Ford's RV and Training Service has an excellent series of videos on RV refrigerator repair and misdiagnoses. I highly recommend watching them all. This link goes to #3 which discusses the drain. Link

Yes, it IS important. An open condensate tube allows warm air to migrate up the tube (hot air rises). This over-works the refrigerator and adds to excessive condensation. You want water to be able to drain, but NOT for air to be able to flow freely.

In the installation manual it's called a 'black water check valve' but all I've seen is just an insect plug in end of drain tube....plastic plug with small holes in it.

Parts manual lists it as 'discharge pipe, plug'
Item #7 on page 7 & 8.........LINK

EDIT:
Yep.......that's it (AtomicChicken)

This is it here....

dometic drain plug

enblethen wrote:
Small screen type device on end of drain tube.

....which often gets plugged up with dirt and stuff. I just removed mine and no issues.

Small screen type device on end of drain tube.