The heating is not hot, please advise!

Your question is normal, because after changing to a single household cycle, the original top-down series heating mode has been changed to a bottom-up parallel heating mode, so that the top floor where you are located has changed from the first heating end to the end, and the heating pressure is smaller as you go up. It's just that your situation illustrates this. The reason why all the water is hot after being drained is that it returns to its original state after one hour, because the pressure can't be reached. When waterproof, because there is no water pressure at the outlet, the pressure in the inlet pipe is enough to heat the heater. But once return pipe is connected, there will be pressure in return pipe, and the water pressure difference between the inlet and outlet is small. Finally, the pressure difference between the inlet and outlet may be very small, so this will happen to you. Solution: add a booster pump to the water inlet pipe of the house to increase the water inlet pressure, so your problem will be solved! Finally, I wish you good health and good health! I hope I can help you!