Plumbing in the Home/Hot water circulation
QUESTION: I have very limited hot water unless I turn on the heater. The hot water apparently circulates through the heater, but should it be necessary to run the heater to have hot water?! Could there be a "diversion" valve (just guessing at a term) or something that is not working?
ANSWER: Hello Anne,
Domestic hot water system and hot water heaters are designed to run continuously. As you draw off hot water, cold water automatically enters the tank and is reheated continuously. The hot water is drawn off the top portion of the tank and the cold water is introduced through a long tube to the area near the bottom of the tank where the burner is. If you turn off the water heater, it will gradually begin to lose heat to the environment, even more if it is in an unconditioned (unheated) area like a garage or an attic.
Turning the water heater off and on between uses actually wastes energy because it takes more energy to heat cool water than it does to heat already warmed water. You will also have to wait longer to get hot water out of the faucets.
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QUESTION: I failed to explain that it is the apartment unit heater and not the water heater that has to be running in order for me to have sufficient hot water.
From what you are saying, both the domestic hot water and the heating system appear to be connected together in some way. This is a bit unusual and not a standard implementation that I am aware of. Hot-water heating, also called "hydronic", is not very common out here in California where the bulk of my experience lies. It is more of a Midwest and East heating system where boilers are more common.
I would check with the people responsible for maintenance of the apartment complex and its systems to see if something is not working as it should. This doesn't sound like the correct way.
Typically, domestic water systems and hot-water heating systems are set up to be independent of each other. They may be supplied by a common hot-water boiler but should be isolated from each other to avoid the problem that you are experiencing.