The Takagi on demand water heater suddenly only has cold water I contacted deck support and they finally told me to shut off the cold water gate valve to the water heater and turn on the hot Ok I still have water coming out so they said somehow I have a cross connection where cold is mixing with hot How can this suddenly happen I have not replumbed anything Help is appreciated Thanks

A single handle faucet or tempering valve can be the cause of the cross connection.

ok thanks Steve so how do I address this issue as the price philter single handle shower valves do not have s shut off should I replace the valve cartridges in the 2 showers showers ? the Takagi control box says incoming 50 degrees the began climbing slightly ?One more thing Takagi deck support said turn off the water supply to the heater and if water still comes out of the hot faucet you have likely a cross connection please elaborate on this thanks



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A failed pressure balanced cartridge in a shower valve can suddenly cause a cross-connection. Just a thought. We find this issue with the older Grohe thermostatic valves when the check/screens fail.

So in order to try to address the tankless water heater cross connection I should replace the valve cartridges in the 2 single handle price Phister shower valves yes Because the valves I do not believe have the shut off screws at the valve to io
slate the water flow issue Correct thinking yes? THANKS thoughts ?