We have suddenly started experiencing extreme temp variations if someone flushes a toilet while someone else is showering — shower gets extremely cold, new issue after 15 years living here. Also when I run my kitchen faucet, it has more recently begun getting ice cold when first turned on, literally 1 second after turning off after running very hot water and still set to hot. Only new thing is this faucet, a gooseneck no-touch my husband installed. Water heater is pretty new. Ideas on the cause and solution? Thanks!

  • Typically with this type of problem when someone flushes a toilet the shower gets too hot because of the drop in cold water pressure caused by the flush. Are you sure it's the other way around? – HoneyDo Dec 6 '20 at 4:42
  • Yes I’m sure. :) That’s why it’s confusing and I didn’t find anything good in a Google search for resolving it. – Flipper Dec 7 '20 at 13:42

If it was just the shower, I would look at the shower balancing valve.

But you say this is happening almost identically in the kitchen? It is possible that the valves for the kitchen are not both opening at the same time.

You could appraoch this as two separate problems, even though they seem related. I suggest these steps:

  1. contact the manufacturer for the kitchen no-touch, and describe the problem to them. They will walk you through the diagnosis.
  2. When that issue is resolved then go after the shower. What happens when running a sink faucet and the toilet is flushed?

A likely area in general is restrictions in hot water heaters, but you get this with flushing the toilet. What kitchen faucet model, and what kind of shower control do you have? What kind and style water heater do you have? Tank, on-demand? Meanwhile chase down the steps above.

  • Thanks, will take a look. It’s a tank, not on demand heater. Usually has plenty of hot water for all 5 of us. Shower valve is only a couple of years old, but head is newer, I just didn’t think a new head could change anything. – Flipper Dec 7 '20 at 13:45
  • I agree there should be plenty of hot water. There are strange things that can happen. For example, years ago (15?) there was a rash of dip tubes for hot water heaters, which put plastic in the hot water lines, and caused cold water to enter farther up the tank. I look forward to your device models / descriptions so that I might help further. – mongo Dec 7 '20 at 15:28

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