Hot water intermittent

[Sparkysprks5]

The last couple months when I turn the shower on I either have to turn the water on mostly hot or it will go cold. If I turn the faucet to warm it gets cold until I turn the faucet back to all the way hot. My house is only 4 years old and it long does this in the master shower. Also I have a tankless gas water heater. I need help.

 

[phishfood]

My first guess is that you need to get the cartridge in your shower valve replaced.

 

[Sparkysprks5]

I replaced the cartridge but it didn't seem to help. I thought about maybe buying another one to see if the first one I bought was bad from the store.

 

[Debo22]

You're not moving enough water through the heater to keep it on. Your shower head is clogged or the output temperature is too high.

 

[Sparkysprks5]

I changed the shower head and it fixed the problem. The old head didn't seem to be low on pressure but I guess it was clogged just enough to effect it. Glad it's fixed and can't believe it was something so simple.