My house is on a slab. In the main bathroom, when you turn on the hot water in the shower, it just trickles. The cold works fine. Both the hot and cold water in the vanity work fine. So i thought the shower valve was bad and replaced it. Still no hot water. So I think I have a leak in the hot water line between this shower and the vanity or, some calcium build up clogging the line. So I stuck my air hose down into the hot pipe and blew air into it. But water came gushing out of the cold pipe. This makes no sense to me. Is it possible I blew water through this hot pipe, back to the vanity, through the vanity faucet, and back down through the cold pipe, and out the cold pipe here at the shower? I’m going to re-plumb this shower and see what I get. But does anyone have any ideas why there’s no hot water or how the air pushed water out of the other pipe?

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