Why Would Tankless Water Heater Go Cold Mid-Shower

Updated 03/11/2024 | Published 01/06/2023

Question:

Unit gets to temp and water i warm. Half way thru a shower it shuts off and cold water comes thru. Is there a timer on the water? Very distressing to take a cold shower i this weather.

asked by: John C

Expert Reply:

Typically when a tankless water heater goes cold mid shower it's because either you flow of water is too much for the heater to keep up with, or ironically the flow of water is too low and the heater doesn't think water is passing through and it shuts off.

Most likely it's too much water is coming through it and it can't keep up. Are there other people using hot water at same time? There isn't a timer in the shower for it to turn off.

It could also be that your gas level is too low.

expert reply by: Jameson C

Mark C.

3/11/2024

Our new AO Smith signature electric on demand water heater gets hot then get cold after two or three minutes.

Jameson C.

3/11/2024

@MarkC We don't carry that brand so it's harder for us to troubleshoot but I would check to make sure you have enough propane, your regulator is in working order etc.