During my inspection yesterday for a one-year new home warranty, I asked my client if he had any concerns with the house. One of his concerns was with the plumbing, specifically with the mixing valve installed on the water heater. The coldwater coming from the kitchen faucet will warm up but not stay at a consistent temperature after he has been using the outside hose for a while. I took a sample of the coldwater temperature from both the kitchen and the powder room that is not on the mixing valve and there was an 11 F difference in temperature. Should there not be some kind of check valve to prevent hot water going back into the coldwater distribution?
Yes there should be a check valve inside the valve. But the way you explain the problem it sounds more like you may have a pressure or volume problem. On something like that i would do a flow test. Well not as a inspector. refer it to a plumber for evaluation and repair
I’ve referred it to a licensed plumber for further evaluation and repair as necessary and to check for possible flow or volume problems. Cheers,