harold1946 wrote:
Water expands as it freezes, that is what causes piping to break, not water pressure. Even with the pump off there is still water in the lines and the pump.
Listen Harold, you know a lot of stuff but on this one you are just plain wrong. Just ask any plumber who is over 40 years old.
IF....the water in the pipe has room to expand in both directions without building up excessive pressure, that is one end slightly open (faucet) and the other end still connected to the input at ~40 PSI, the ENTIRE pipe can freeze solid with no adverse effects. This is why it is NOT a good idea to turn the source off in a "city water" situation and instead leave the faucets drip.
I know it's somewhat counter-intuitive but it IS true.
With an RV, the opposite is true. Since turning off the "pump" does not actually block anything, you do that and open the faucets. This assumes, of course, that you are NOT still connected to an outside source of water.
