Hello,

I have a three zone gas water heating system. Two zones provide hot water for baseboards. Third zone is for hot water in house.
After cold season started I began to see water on the floor. I found it is coming out of pressure relief valve.
I can see that air pressure gets to 30-32 psi when couple of zones running. That is were water would flush out of the relief valve.
When system is off, the pressure was around 20 psi. I thought it is high and that is why it gets to 30 when it is running.
So, I adjusted the Fill Valve. And the pressure went to 15 psi. But still when running it gets to 30 psi and water leaks from relief valve.
Then I checked the expansion tank. It had no pressure. So, I used air pump to get it to 15 psi.
And I get the same result, 15 psi when nothing runs, get to 30 psi when running.

Any advice on what else I need to check or could be wrong with the system?
Thank you