Hot/Cold AO Smith Tankless

[drainklogg]

Hi, I have a 5 year old AO Smith Tankless. My 2nd floor kitchen faucet will get hot when I turn it on, however after several seconds it turns cold and will not come back. I did notice that if I run the bathtub faucet on hot the kitchen will turn hot again. Is this a faucet problem or a water heater problem? I can tell you that I have never done any maintenance on the tankless including flushing, which I now know I must do.

Please, any advice welcome.

 

[Geofd]

Is it a single handle faucet.... If so shut it off under the sink
then try your other fixtures then turn if on again and see what
the differences

not sure what causes the cross over I removed the faucet
and installed a two handle the one I took out was a zurn
they are not known for faucets I have Installed lots of single
handle faucets had no problems

could be a bad cartridge or a nick in the ball style
try to rebuild it first/then replace with a two handle

 

[drainklogg]

It is a single handle faucet and I will try when I get home.

 

[drainklogg]

I did just that last night and it seemed to work and got real hot. Then this morning the hot was running cold again. I centered the single handle while on and the pressure seemed to pick up I then slid it over to the hot side and the pressure is much less but it got hot and stayed hot for a good few minutes. I'm trying to figure out the logistics of how your suggestion works, and it did.

I think the hot is running more hot since I tried what you said. Does that make sense?

 

[Geofd]

I edited my last thread if you leave the hot and cold valves closed
under the sink closed all works normal???
When you turn on the valves under the sink it doesn't work right
If so it's the faucet

 

[TomFOhio]

What kind of faucet is it.