View Full Version : Hot water backflow

12-04-2008, 11:04 AM
If the hot water hasn't been used in a while and I grab the tanks intake it is just as hot as the output. I'm assuming there is some sort of backflow preventer to stop this energy loss. What should I do to fix this?

If it matters, it's a kenmore tank built in the early 90's. There are no sweat connections near it so that couldn't have damaged anything.

Is there any maintenance I should be doing to help this tank out. I really can't afford a new one and I would like this to last despite it's age. I looked through some threads but found conflicting ideas. Thanks to all.

12-04-2008, 11:14 AM
It is a simple matter of physics. Hot water rises, and it doesn't care whether it is rising in the hot pipe or the cold one, and NOTHING will prevent it only slow the process down. It will only heat up to the point where the pipe turns downward at which point it will start cooling off.

12-04-2008, 01:04 PM
There are a couple of heat traps that are often included on new installs, could be retrofitted, but highly risky on an old WH. One type has a plastic ball in it to limit convection water flow. If you get some mineral buildups, they can stick and block the normal flow of water use. Another type has a flapper valve to close off the inlet and outlet. Eventually, they leak. They must be installed on the correct port, or you won't get any flow at all when you open a faucet.

If you don't have any insulation on the pipes, you can save a little energy if you install some on the hot water pipes (somebody calculated about 13BTU/hour/foot of 1/2" pipe, if I remember right - it was in a Fine Homebuilding issue recently). Insulation can cut that, and keep in mind, not much of the pipe will be hot unless you are running the hot tap regularly, so the loss would taper off in between uses.