Bath faucet water stays hot, but shower is cold

[sidegate]

Hi - I wonder if anyone can help with this problem.

I have a bathtub with a line to the tub faucets with a lever that switches flow to the shower head.

If I run hot water through the tub faucets, it stays hot. Once it is pushed up to the shower faucet though, it is warm for about 1-2 min, and then starts getting cold. If I turn on the shower directly, without going through the tub faucet, it never warms up. But if I drop it back down from the shower, to the tub, it’ll start getting hot again.

Any help would be appreciated.

 

[johnjh2o]

Can you tell us the make faucet you have? If not a picture may help.

John

 

[sidegate]

Aquatic - the fixtures were installed about 6 years ago. I've attached 3 pictures. The water heater is tankless - we've encountered no problems on any of the other plumbing installations in the house though

Thanks

 

[johnjh2o]

The problem your having is from your tank less heater. They work with flow rate. When you turn on the tub faucet the flow rate is much higher then when you use the shower. I would contact the manufacture of the heater. It sounds like a flow switch problem.

John

 

[IFIXH20]

sidegate, removed the shower hose from the fitting coming out the wall, place a bucket under fitting, activate shower to see if water gets hot. If water gets hot the problem is in the hose,head ,or protected screens.

 

[johnjh2o]

By removing the shower head you are increasing the flow rate because there are flow restrictions in the shower head. So if you get hot water without the head attached your back to the problem I believe it is. The tank less heater isn't firing because of a bad flow rate censor.

John

 

[sidegate]

Thanks for the input everyone, I'll post an update in due course