We have a brand new gas & electric water heater. Purchased in 2013. For some reason, when we turn on the hot water in the master shower, it only gets lukewarm unless one of the sink faucets is also turned on.

I know another person posted a similar question, however, ours is not a tankless water heater. Ours is a 70-gallon water heater.

As a note, we do have a timed circulator attached to the heater. And we have set it to run at the right times. Even still, the shower wont' get hot unless we also turn on a sink.

Another note, we've also removed the mesh inside the shower head so there is no restriction on the water pressure.

Any advice would be of great help! Thanks in advance, Lilly

  • I'd put a phone call in to whom ever installed it, and another one in to the shower faucet manufacturer. Which items are new besides the heater? What brand and model of shower faucet? circulator? Does the 'trick' work with either hot or cold sink faucets, or just with hot, or just with cold? Does it depend on the flow in the sink, or does a small stream suffice? Once it is flowing hot in the shower, can the sink faucet be turned off without interrupting the hot shower?
    – mike
    Commented Aug 3, 2013 at 5:24

1 Answer 1


I had a similar problem and it was the the anti-scald function of the shower faucet(which works off water pressure). I had to pull the handle and trim off of the shower valve and adjust the valve with a little allen wrench.

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