shower water gets cold too fast

[pf4711]

Hi,

I have a Smart Phase III 36-gallon water heater. The shower water starts hot but rapidly gets cold. Even in a 7 minute shower, you are turning up the heat again and again, and by 7 to 10 minutes, you have the shower on the max heat setting.

How can I diagnose the problem with the water heater and what should I do?

I already replaced the shower trim and cartridge for unrelated reasons.

Thanks,

 

[DIYerOnLongIsland]

If electric water heater, maybe bad lower element?

Or a bad dip tube?

 

[IFIXH20]

Is this a on going problem or just started ? Have you replaced the shower head or removed the shower head flow restrictor ?

 

[pf4711]

It's been ongoing since we moved in 2 months ago. I have not done anything with the shower head.

The heater is actually a triangle tube smart phase 3 indirect fired heater, which I believe means that it's actually the Buderus boiler next to it that is providing the heat. The boiler also provides heat for radiant heating.

I know nothing about this stuff and I'm just trying to see if there is anything I can try before calling a plumber.

The smart phase 3 is set on max temperature, and the buderus setting for the water that's not for the radiant heating system is set at 140 or so.

Thanks