Hello all! This is my first question to the community!

My bathtub faucet is a 2 handle roman arc setup with a 3-hole fixed roman tub valve. Just recently, my running water is only warm with no hot water coming from the hot valve. All the other faucets in the house get extremely hot, but this bathtub faucet only get warm when turning the hot water valve ONLY. What can be causing this issue? I would think if I only turn the hot water valve I should only be getting really hot water, not just warm. Any ideas?

Thanks for any help!

Is the flow restricted on that hot water stem, too ? When you turn the hot water handle, does the entire stem spin around ?

Back to you

Milo

It does not seem that the water pressure is restricted. There seems to be a full flow when I turn the hot water stem only (leaving the cold water stem closed). After having the hot water turned all the way with the cold water closed, the pressure seems fine but the water is only warm, not hot like the other faucets in the bathroom.

Is it possible there is some kind of mixing valve below this setup?

So you are saying - all other fixtures in the same bathroom have hot water - only tub has luke warm ? How far is the tub from other fixtures in that particular bathroom ? Is your house on concrete slab or is it raised foundation ? if you let hot water run for - let's say - 10 minutes, water is still only luke warm ? Can you snap and post photo of that faucet ?

Back to you

Milo

Yes I will post a photo of the faucet when I get home. You are correct, only the tub has luke warm water. All other faucets have hot water. I am located in Houston, TX and my house is on concrete slab.

If I run the hot water for 10 minutes, it gets colder as it runs.

Do you by any chance , have a hot water recirculation line?

Turn on a faucet where you get hot water. Go to water heater and feel the hot water out pipe. Turn that faucet off and then turn on the hot faucet of the tub. Feel the hot water out pipe of the water heater, does it feel the same?

Tonight, at night, when noise pollution is down - go to the tub faucet and put your ear on hot water valve. Do you hear hissing sound ?

Back to you

Milo

I'm betting on a thermostatic mixing valve. In my area, we are required to install these valves for all soaking tubs, whirlpools and indoor jacuzzis. Bfusel2, look under the sink(s) in your bathroom... most common place I put them. Otherwise, it could be under the apron of the tub (remove apron if possible and see if the valve is there).

If you find the mixing valve you can try to adjust the valve to increase the temperature. If that doesn't work then most likely, you'll need to replace the internal element and spring mechanism which will only be found at a local plumbing supply wholesaler or online. Worst case, you'll need an entirely new mixing valve... see my image

Attachment 48387

Let us know what you find...

Mark

Bfusel2,
What is the source of your hot water? Most large tub valves have flow rates of 5 - 10 gpm, and some can even flow up to 15 gpm and higher; If your domestic hot water is being supplied by a tankless coil, or direct fired tankless water heater, there won't be enough hot water. Tankless water heaters typically produce 3 - 5 gpm at a 70° rise which is fine for kitchen and lavatory faucets, and, shower heads that match those flow rates...