Shower hot water problems.
Domestic hot water source Weil McClean Gas furnace.
Tenant described problem: Turn on hot water. Initially scalding for about two minutes, then cold, then wait and it warms up, but not to hot.
I went to the apartment. Filled the tub Delta faucet all the way open to hot. Using a stop watch to measure time intervals of changing temperature. Initially scalding, but I continually kept placing my hand in the flow of water back and forth, the scalding water lasted for 3 minutes, then it reduced to what I would consider hot that lasted to the twelve minute mark at 12 minutes the water could be considered warm. At fifteen minutes the water hit the drain level. I turned off the water and tested the water in the tub. It was I and the tenant agreed to be a hot tub of water. I waited about 10 minutes and I turned on the shower. Again the Delta faucet was full on to hot. Again the water was scalding. I did not adjust the water, I kept it full on. There was no appreciable change in the water temperature for 11 minutes. I asked the tenant if someone was using the kitchen sink, or the washing machine, or the bathroom sink while they use the shower. He said no. My only conclusion is that when the water comes out scalding they, naturally, adjust the faucet to cool the water. What I cannot explain is why then, when they call for more hot water it does not return for a couple of minutes. I am relieved to learn that the furnace is delivering an adequate amount of hot water, as the tenant was requesting a separate hot water heater. Do you think that this might be a result of mixing valve
at the tub? It has a push button to activate the shower. Not a very expensive unit.