Have HVAC Questions? Ask an HVAC Expert for Answers
Hello, the problem is that the mixing valve (tempering valve) on your hot water tank has the cold water supply pipe valve closed to it, OR its stuck in the wrong position.
Lowering the boiler temperature would work, but not very well, as that temperature cycles 10 degrees hi and lo, and if you set it to 120F you are likely to find the boiler water is not hot enough to heat the house.
Get me the brand and model number of the mixing valve that you are adjusting, we can go from there.