No hot water, mixing valve

milford4525

Hello everyone!!!
So here’s my situation, we have a boiler that heats our house and our hot water. I don’t have any kind of loss of pressure with the hot water which makes me think the coils should be good? Yet, our hot water never actually gets hot in our shower. Warm at best. But sometimes won’t even get warm. Recently it’s gotten even worse. Now with our mixing valve, the pipe going in hot to the valve is scalding, however the mixed pipe going out (with it all the way open) is not. I can grab it no problem. It’s almost cold. There is a lot of build up on the pipes where the hot water goes into the mixing valve. Do you guys think this could be a solution for me? Changing the mixing valve?

Jamie Hall

Mixing valve is probably gunked up and stuck. You might be able to persuade it to free up... maybe... with vinegar or something. Or you could just replace it.

Jellis

you may be able to buy a replacement kit for your mixing valve, keeping your body and eliminating soldering and pipe cutting.
This would be by far the easiest thing to do.

milford4525

Awesome!! I’ll check that out! Thank you

Intplm.

Jellis said:

you may be able to buy a replacement kit for your mixing valve, keeping your body and eliminating soldering and pipe cutting.
This would be by far the easiest thing to do.

Before you do that. And it is good advice. Make sure that this problem is occurring at all hot water faucets including the above mentioned shower.
If it is happening at all of the hot water faucets then that is the place to go if it is a "true" mixing valve and not a tempering valve.
If it is a mixing valve, a kit is probably available to correct the problem.
If it is a tempering valve. Say a watts LFL70A or similar. Do not try for a rebuild. It will not work as they do not rebuild well and will continue to give you the problems that you are describing soon after the rebuild.
So. Instead, install a true mixing valve in its place. No tempering valves.

If it is only happening at the shower. It is probably just the shower, and not the mixing, or tempering valve.
If you find that it is just the shower....we will have to discuss that further.

hot_rod

By true mixing valve I believe Intplm means a listed valve
ASSE 1017 goes at the water heater or coil. ASSE 1070 is a higher protection valve that goes at the fixture. Often both are used, point of distribution and point of use.

Remember the numbers by the higher number valve is the higher protection listing.

One problem with a rebuild is you need to descale the body also or the new cartridge will be compromised. If you can even get it in.

Pumping a mild acid, like a tankless water heater kit is a good way to salvage lime scaled valves.

I built this kit to salvage some of the warranty returned valves for my own use.

milford4525

These are a couple pictures. I appreciate the info because I really don’t know a ton about this stuff. Only what I’ve researched online and have read on threads here. So the top pipe is the hot and as I stated the water going into the valve is super hot as I can’t even touch the pipe. But under the valve coming out the “mixed” side, does not feel hot at all

hot_rod

I'd say you are due for a replacement. Any idea if it has ever been serviced, disassembled, cleaned? In some homes valves like that need a yearly service if they have extremely hard water.

Shop for an approved, listed ASSE 1017 thermostatic mixing valve.

Looks like you have some isolation valves to simplify a replacement.
The one below with the handle in a yoga position for example

Intplm.

hot_rod said:

I'd say you are due for a replacement. Any idea if it has ever been serviced, disassembled, cleaned? In some homes valves like that need a yearly service if they have extremely hard water.

Shop for an approved, listed ASSE 1017 thermostatic mixing valve.

Looks like you have some isolation valves to simplify a replacement.
The one below with the handle in a yoga position for example

@hot_rod is right on target here. And as before mentioned. The valve that is pictured is a tempering valve and not a mixing valve. Replace this with a "thermostatic mixing valve."

GroundUp

Those tempering valves are, for lack of a better term, a piece of crap. Half of them didn't work even when they were new, so you got your money's worth. A Honeywell AMX thermostatic mixing valve would fit nicely in that spot with minimal piping modifications and they work fantastic

milford4525

Awesome! Thank you guys so much!

milford4525

Are these hat you guys are talking about? Any preference to either one?

hot_rod

It's nice to have a gauge sometimes, and larger bodies handle scale better. Support one of the many brands that supports this list

Intplm.

Yes! Those are the ones. A company by the name of Symmons also makes one. The Honeywell and Caleffi all good choices.

Jean-David Beyer

I have a Caleffi 1070 type valve (521352A) located at the indirect hot water heater (where usually a 1017 type valve is used). I picked it, in part, because it could regulate all the way down to 1/2 gallon per minute, where 1017 valves went down only to 1 gallon per minute. Caleffi state that the materials used in the valve's construction resist lime-scaling.

hot_rod

Here is another option, the angle pattern cleans up the piping, this also has that .5 gpm range and is 100% shut off on the H, so an easy valve to use in recirculation applications to prevent temperature creep. Mix and match connection tailpieces.

GroundUp

The AMX in your first photo comes hot in the bottom and mixed out the top with cold in the side, so would be piped in the same configuration as your existing tempering valve and be pretty easy to swap, and they come with a thermometer strip. All others I've seen are piped with hot and cold opposite and mixed opposite the knob, so would not fit nicely in your piping. I use a ton of the AMX in both domestic and hydronic applications and they've been flawless, as well as saving a ton of time

rvet

I had this same issue. Water would not go over 35 degrees. I replaced the thermostatic mixing valve and it kept happening. I knew it was still the valve because the water I drained from the pipe was scalding me as I changed it. My problem ended up being that I just had my water softener set TOO hot (160 degrees). I had it all the way up and I guess it was tripping the valve to lock up tight. Once I turned it down  to 140, it worked fine. I was able to adjust anywhere I wanted from 35 to over 60 degrees at the faucet. Hope that helps someone.