Low hot water flow

[Bgibbs]

Just filled fresh water tank getting ready for week long trip and I get very low flow when hot water is on. It happens in kitchen, bath and shower. The pump sounds fine on cold water but it responds more slowly when hot water is turned on. Like there is a delay in sensing need for pump. I made sure that all air was out of lines and water heater. Made sure bypass valve is open. No visible kinks in hot water lines. We are usually on FHU.
Any ideas appreciated.

[rowiebowie]

Recent thread here could be valuable.


http://www.airforums.com/forums/f540...er-203206.html

[Bgibbs]

We get hot water in sink, bath and shower, just low volume. Cold water is normal.

[abqdor]

I had exactly the same problem earlier in the year after winterizing. Cold was fine, but hot was a trickle. My particular problem was at the mixing valve of the hot water heater. The mixing valve itself was fine, but there was a spring that had come unseated causing the hot water flow to be restricted. After repositioning the spring, everything started working again. Here is a link to the thread that shows pictures of my problem.

http://www.airforums.com/forums/show...errerid=103283

[AlinCal]

Do you have a tempering valve? commonly called a mixing valve as well.
Google found this:
http://www.airforums.com/forums/f445...ve-177432.html

[drbrick]

Interesting - not had this happen yet - wonder if there is hard water deposit in the lines???

[J. Morgan]

Well it's a restriction.... I guess we all know that, the trick is going to be finding it.

Is there a valve somewhere that isn't obvious?

[Wetfeet]

For a long time I thought the problem was a stuck temperature mixing valve. However, I finally determined that air gets trapped in the piping near the hot water heater, which then restricts the flow of hot water to all the faucets. If you open the dump valve on the hot water piping that’s under the water heater with the pump on (or city water hooked up), you can blow the trapped air out of the piping. Then close the dump valve and you should get good hot water pressure at the faucets.