The pilot light on our tankless water heater has gone out and won't re-light. Any ideas what might be causing it?

Could it be the thermocoupler? Or other?

Thanks much.

Tankless water heaters generally do not have a piolit light? How old is the unit?

Yes, pilot light, I guess older units would but if it is that old, perhaps time for a new one anyway.

The burner will not light of course if there is not enough water volume / pressure since most have a pressure flow switch.

What brand tankless heater is it ? Do you have power going to the unit ? Is the control pad lighted displaying temperature ?

Hey, thanks for the thoughts.

I inherited the unit (Myston 325) when I bought the house 3 years ago, could be maybe 10 years old.

It does not have a digital display, frankly I've scoped the thing thoroughly and cannot locate a temp adjustment at all. Surely it must be there?

I don't think that "power"/electricity is involved at all. Its powered by gas and I have gas to my stove, so I'm thinking that's not a problem.

I do have a serious leak going on to a different hot faucet, but that's been going on for several weeks (old tub, can't find replacement I want yet). So that wouldn't influence the flow regulation at this time, would it? All the time that its been leaking we've had hot water until now.

Thanks for any ideas!

First, make sure there is gas going to the unit. Then, Replace thermocoupling...

First, make sure there is gas going to the unit. Then, Replace thermocoupling...

Thanks milo dolezal

I was thinking that was the likely issue. Just talked to a plumber who wants $95/hour plus parts. If I got some guidance, is this a job that a non-pro could handle?

It is easy to do: Remove the old thermocoupler, take it with you to Home Depot. They may carry it. Buy new one and install it. Pay attention how it is put in when you removing the old one.

If you need help, come back and we will guide you through...

It is easy to do: Remove the old thermocoupler, take it with you to Home Depot. They may carry it. Buy new one and install it. Pay attention how it is put in when you removing the old one.

If you need help, come back and we will guide you through...

Milo dolezal; thanks for the advice. I'm looking at diagrams and where this thermocoupler lies is a tiny cramped space, don't know if I can get at it. Going to think about if I'm going to tackle it.

Really appreciate your thoughts. Thanks much.

LOL ! It is always in "cramped space. See what you can do...