Low water pressure and scolding hot water.. Help please?

[guht]

I have a shower in my downstairs bathroom that seems to have low water pressure, and has scolding hot water.

I made a video and posted it on youtube showing the bathroom and explaining the problem, which can be viewed here https://youtu.be/77-84MUgWao

• The water heater is directly behind the bathroom.
• The water heater is already on the lowest temperature setting, any lower and I have problems with the pilot light staying lit.
• I attached a water pressure gauge to the shower head with the rubber bushing removed, and even with the pressure gauge leaking it read around 80PSI, which I thought was normal?
• I used a measuring pitcher and timer to estimate the flow of water, and the shower spout, bath spout, and sink are all measuring about 3GPM.
• If I turn the shower temperature handle 1/3rd of the way on cold the water temperature is luke warm or cold, but the water pressure is 1GPM.
• If I turn the shower water temperature handle to 1/2 way, the water pressure is close to its peak, but the water is then scolding hot.

Is there anything else I can do or check to troubleshoot and/or resolve this problem?

Thanks for looking!

 

[guht]

Bump... Anyone?

 

[johnjh2o]

Replace the cartridge. The balancing spool is not working. Looks like a Delta faucet.

 

[Mr_David]

Replace the cartridge. The balancing spool is not working. Looks like a Delta faucet.

Not a Delta. Moen Positemp. But I would rep[lace the cartridge in the tub valve to start.

Some times those valve have integral stops ( hot/cold shut off valve )
on the water supply connections to the valve. They are under the cover plate.
if you have them makes sure they are open.

The scalding hot water is a problem with the gas control valve on the heater.
If it's under warranty call manufacturer. Use a kitchen food thermometer and see how hot it really is. I like the digital ones. $10 - $15 at the grocery store