Closed Loop

H2_Oh

I have a oil fired boiler that I get domestic hot water and a hot water heat closed loop. To work on changing my pressure regulator,(a Watts 12-15 psi with a quick fill lever.) and my circulating pump; can I turn off my supply to pressure regulator and drain the closed loop while still allowing domestic hot water to operate. I do not know what the inside of the boiler is like; can the loop be drained of water, and the boiler be firing, with no damage to loop? Thanks.

EddieG

MUST HAVE WATER

Boiler must have water. You can isolate the return and supply, but boiler must be open to expansion tank.