Slowing hot water from bathroom faucet

Mawkins · Dec 31, 2014

Hi all. Appreciate any help you can give me on this one. Hoping it's something really simple and my know-how is just insufficient, I'm a complete amateur but can't afford a plumber. So we have a single faucet for hot and cold water that feeds our bath and shower. I'm currently having a problem with a bathroom faucets hot water flow. Hot water flow is fine throughout the rest of the house, including the shower/bath that the problematic faucet is located in. When I turn on the hot water it starts strong but then fades to a luke-warm at best. The cold water comes out strong. I have replaced the Posi-Temp Moen cartridge inside the faucet. I have tried to change the temperature settings by adjusting the inner white plastic cogs but get it to its utmost limit before the inside of the metal faucet handle stops out. Just confused as we're getting hot water but only for about a minute before it gets too cold for either a shallow bath or comfortable shower. Many thanks in advance.

havasu · Jan 1, 2015

Bump to the top for assistance please.

Mr_David · Jan 1, 2015

Check a few things.
When running the tub, water temperature is hot and okay for a bit. if you're filling the tub how much hot water do you get before it starts to fade? when it does fade, go turn on a sink nearby. Is the water still plenty hot at sink.
is the volume significantly decreased.

The Positemp has a pressure balance spool in the cartridge. maybe the spool is defective in the new cartridge.

Mawkins · Jan 2, 2015

Thanks for getting in touch Mr_David. So I tried what you suggested. I turned on the bath faucet, it took about 30 seconds to warm up then it ran piping hot for about 45 seconds before turning luke warm. I then turned on the hot faucet at the sink, which ran hot, decreasing the pressure and temperature further of the bath faucet flow. So despite changing the cartridge, nothing has changed. This was the same problem before I tried changing the cartridge (which was replaced by a professional plumber about a year ago). It's the only thing I can see to replace, my first attempt to fix it. Any further help/suggestions greatly appreciated.

Mr_David · Jan 2, 2015

so You have had this problem for more than a year and was a problem prior to you replacing the cartridge a year ago.
does your valve have integral stop? make sure they are open. slot in stem horizontal. do you have a hot water recirculating system?

Mawkins · Jan 4, 2015

We had this problem a year or so ago, called in a plumber, he changed the posi-temp cartridge and it was better. The Aqua stat was changed about a month ago, we had a heating technician in to check our big old heating oil boiler as our heating wasn't working (but we still had hot water which also runs from th eoil system). I changed the minimum limit on the aqua stat to 160° from 150°, the top is 180° thinking that would change the hot water temp enough to make the difference but it hasn't...I think the change in temperature was around the time the aqua stat was changed. Where would the integral stop be? We do have the system behind the faucet pictured, the stems are horizontal.

Thanks again.