new expansion tank
I remembered when the plumber install the gas heating system for us he took the expansion tank out from the box and put it into the system without any pressure adjustment. Is that mean the new expansion tank from the manufacturer is ready for use no need to do any tuning?
I think the heating system pressure is the same as the house cold water supply pressure because they are connected with a backflow provention valve. And the ball valve between the water supply and the heating system is open. Should I keep that ball valve open?
Re: new expansion tank
You have an automatic boiler feed valve after the back flow preventer that adjusts the pressure to whatever your plumber set it for. The ball valve before the back flow preventer needs to be left in the open position so the auto feed valve can add water to the hydronic system as required. The plumber should have checked that the expansion tank had a full charge of air. That could easily be done with a tire pressure gauge. Hopefully he did that.