Joe wrote:
I have a regulator coming into the house which I replaced today.

Why would I need an expansion tank now when there has not been one for the
last 9 years I have owned this house and it has not been a problem up till
now? What has changed?
Joe



some areas require anti siphon valves or check valves when plumbing is
worked on or homes sold.

say you have a garden hose in a swimming pool filling it.

the water goes off, suction will pull water from your pool, it might be
yuk dirty and flow to your unsuspecting neighbors.

so a check valve is now required at home sale time.

this makes the plumbing in your home a sealed system. when you hot
water tank heats water the pressure increases sometimes dramatically
and the valve opens.

a pressure tank absorbs the change in pressure