Why is it impossible to connect the water heater to the domestic hot water network?

Hello!

It is technically possible to connect the water heater to the hot water supply, for example, by tapping into the hot water supply pipe with a tee to divert to the boiler. At the same time, contrary to popular belief, nothing bad will happen to the water heater. Upon receipt of really hot water, and not close to cold, the heating heater will simply not turn on until this water has cooled to the desired temperature. This, in principle, is the first problem: if the water entering the boiler is at least a couple of degrees warmer than the heater programmed, then you can wait a long time for it to cool in the tank. Of course, there are models where the user sets the temperature, but most devices begin to work only when the water cools below 40 C.

The second problem: hot water, even if it is not quite hot, goes through the DHW meter. That is, you will pay twice for heating the same water: on the meter, as for hot water and for electricity when heated in a bolera. If you think that in this way you will be able to significantly save on electricity due to the fact that the heater will heat less warmer water, then you are mistaken - the benefit here is very small. The fact is that the boiler spends up to 70% of the electricity to maintain the temperature of the water, and only 30% directly to the heating. If you just turn on the device for heating every time you need hot water, turning off the constant heating mode, then you have to wait 1-5 hours for hot water, depending on the power of the device and the tank volume. As you can see, in order to save money, it is completely pointless to connect the water heater to the hot water supply. This method is justified if the quality of cold water is much inferior to hot.