How long do I let the water run before I know there is something really wrong? It has been 10 minutes and it has not armed from lukewarm. Neither does the but both sinks get fairly hot quickly. What is wrong? It is the bathroom farthest from the heater and has always taken a minute or two to get hot but never this long. I have not used it in 3 weeks...

Your shower likely has an anti-scald feature buit in that needs adjusted under the handle.

What brand is your faucet? Does it have a anti skald feature? Can you give us more details. Back to you, Tom