Water Heaters - Please explain a "heat trap" to me.

I just bought the new water heater. It came w/ dielectric "heat trap" nipples. Can you explain how these work? I have also seen piping diagrams depicting a 6" drop in your piping that is called a heat trap...

How does all this work out in the real world? Are these nipples a modern substitute for the old pipe drop scheam? Just curious because I want to do my new install the best I can. Thanks-

Heat Trap fittings function as check valves on the hot and cold water lines at a water heater to prevent convective movement of water. They operate by having lighter or heavier-than-water balls which seat on the valve when there is no water flow.

Yes, those fittings are a substitute for the old drop pipe method. Either will work just fine.

It's intended purpose is to stop any gravity hot water from traveling up the piping and being wasted.

What brand water heater did you get?

I just bought the new water heater. It came w/ dielectric "heat trap" nipples. Can you explain how these work? I have also seen piping diagrams depicting a 6" drop in your piping that is called a heat trap...

How does all this work out in the real world? Are these nipples a modern substitute for the old pipe drop scheam? Just curious because I want to do my new install the best I can. Thanks-


Today's heat trap nipples are commonly a little rubber flapper which in essence acts as a check valve. The purpose is to keep heated water from migrating by natural convection up the pipes, where heat would be lost and thus energy wasted.

They are not a true check valve, in that water will flow under system flow demand, but convection does not cause enough force to overcome the 'springiness' of the flapper.

In the end I got the GE from big orange. Made by rheem. Anyway, it seems like a good unit. Works well anyway.


So I installed my copper pipe to these "heat trap " nipples. But in a short while my cold water feed pipe is hot to the touch about 3 feet away from the tank. The hot water pipe is warm, not hot, for about the same distance.

I thought the heat traps would have stopped this. I think I am going to cut in and put the "drop pipe" traps in place. Hope this stops the heat migration. I also plan to insulate these pipes. Hope this all will help out.

Well, you'll still get some heat conduction through the pipe material itself, I would think. The heat traps just prevent natural convection in the water inside the pipes.