"Dan Listermann" wrote in message
...
Our cold water faucets always produce an initial stream of hot water
before the cold starts. I believe it has to do with the expansion tank on
the heater. There is a check valve on the water line that feeds the
heater, but the backflow seems to indicate that it does not work. It is
the flapper type and it is pointed down. Is there a problem with trying
to use this sort of check valve in a downward position? I checked the
arrow marking and it appears to be installed in the right direction.

In addition to the advice others have given, it may help to know that
crossflow leakage when a single handle faucet is turned off is possible and
can cause your symptoms.

Don Young