Here's one that's got me puzzled. It's in a one bath, one kitchen
apartment that has it's own WH. The bathroom was piped by the former owner,
so anything is possible (it's the same place that almost killed me two
months ago). All the faucets are two handle, and there's no laundry.
The problem is that the cold water never gets cold. It's always lukewarm
or hot. I thought it'd to be a simple cross connection somewhere, but it's
more complicated. Here's what happens. When I go to the WH, and hold the
pipes when the hot is run, the cold inlet gets cold, and the hot outlet gets
hot (which is normal of course). But when the cold is run, the hot water
backs through the WH, making the cold inlet get hot.
So what could make hot water come backwards through the cold inlet, and
then throughout the rest of the cold system?
The only way I can think to fix it is to put a check valve in the cold
inlet, but it doesn't ease my mind any.