I originally posted asking what you see in the pictures due to me being 5 hours away from the person who needs some service. The responses were that it was an anti sweat mixing valve with an elbow which then later I got better photos to see that.

I've faild at attaching a link to a diagram of what is most likely inside but this is probably not the same brand. I assume it's similar with the check valves, springs and o-rings. The diagram is on home Depot website for" Legend 1/2" anti-sweat valve" under additional resources. I tried attaching the link to the PDF as well as just the link to the product and I can't figure out what you need to do because it's failing with an error message.

She says currently the water from the sink cold water supply and the toilet water feel the same temperature. I understand these can be service but my question is if it's never been opened will the rubber pieces be an issue. Could be 15 or 20 years old.

enter image description here

Further update is I got better pictures sent and all the answers were correct. elbow soldered in mix under side

  • 2
    Picture's at just the wrong angle, but I think the right hand fitting has an elbow (soldered in rather than compression - some fittings are multi-use - or I'm seeing things that aren't there) going back to the wall rather than being empty. If empty, presumably it has a valve like the left side and that valve is shut.
    – Ecnerwal
    Commented Nov 18, 2022 at 1:36
  • 1
    You might be right because I can't see how it would be connected to the back side or not be leaking out the cold water inlet. He was a general contractor with plumbing experience so maybe he sweat something in so I'm trying to get her to take some more pictures but I don't want her to struggle on the floor at her age.
    – Mstar
    Commented Nov 19, 2022 at 3:01

2 Answers 2


I suspect it's a tempering valve similar to this one. enter image description here

It's used to add some hot water into the cold water that fills the toilet tank. That keeps the tank warm enough to prevent condensation ("sweating") on the outside of the tank.

  • Yep, definitely looks like a mixer valve to me Commented Nov 18, 2022 at 3:39
  • But there is no connection to the 2nd input so it's effectively doing nothing. Perhaps it was being used to adjust the flow on the "HOT" side, which is probably really cold supply line, to keep the bidet from shooting across the room.
    – jwh20
    Commented Nov 18, 2022 at 10:12
  • I agree it's a mixing valve and I'm having her confirm that the cold water from the wall might be just soldered in and it be poor photography. It sure does look like a flare end on the right without anything attached. Why do these things have brass hex nuts on the top. I can understand why the side with the set screw might have one but why does the cold water have just a non-adjustable hex nut rather than just be cast. Is it for some sort of servicing?
    – Mstar
    Commented Nov 19, 2022 at 2:55
  • What will happen if the mix needs to be adjusted and hasn't been adjusted for 15 plus years? Does the set screw have any rubber components and by turning after sitting could leak?
    – Mstar
    Commented Nov 19, 2022 at 2:56

The top after the shut off valve looks like a basic T which appears to be unnecessary, just the valve itself would have done the job to hook up that hose that I assume goes to the toilet.

The set up under the shut off valve is the so called anti sweat anti condensation valve.

That is what I see.

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