Too much hot water from bathroom faucet

Question

Hoping to get some guidance on what the source of my issue might be: I have a single handle bathroom sink faucet which provides very hot water when the handle is set for "warm" water. I tried reducing the incoming hot water by closing the shut off valve about halfway. Now when I try for warm water I get:

• cool water when the handle is set to full open
• cool to warm when the handle is opened half way
• burning hot when the handle is opened slightly

I have already changed the cartridge in the faucet. Might the incoming hot water line pressure be too high? If yes, is there a way to reduce it?

Answer 1

The shutoff valve (or, indeed, water pressure in general) is not a good way to control the hot water temperature.

You either need a faucet with a built-in and correctly functioning (and correctly adjusted, if adjustable) tempering valve (sometimes referred to as an "anti-scald" valve), or you need a tempering valve on the hot supply to the faucet.

The vast majority of faucets produced in the past 40 or so years have an anti-scald feature built-in, as many countries require that feature in their adopted plumbing code.

One approach is to put a tempering valve for the whole house on the outlet of the water heater.