Domestic hot water recirculation problem

Tim_59

I use a grunfos uP15 with a timer. I run my hot water at 140F. I mix it to 120 and all is well except when the recirc pump runs. The temp goes to 140F in the line until a faucet is cracked and then the cold water tempers it.
I have tried aquastats and they still do not help the problem. Has anyone else run into this situation and cured it? I think if I used the grunfos up10 with an integral adjustable aquasta it would help but not cure the problem. I have noticed Armstrong make units with digital controls.
Has anyone used the Armstrong controls?
Tim

Derheatmeister

Maybe your recirc line is not tied in correctly ! Some pix/Drawings may help ! BTW honeywell Braukmann makes a Antiscald valve that has the recirc port build into the valve! that should make the install easy'r. Richard from Heatmeister.

Tim_59

Some pictures

I will look into the new valve.
Tim

Uni R_2

Pump Direction

Any chance your check valve and pump are backwards and you are drawing water from the bottom of the tank instead of pumping into the bottom of the tank and drawing through the mixing valve?

Tim_59

I think that scenario would give me cool water in the line.
The pumps is flowing correctly and the check valve is in the correct orientation. I had the check valve above the mixing valve with the same results. I may move it back above the valve, Sparco diagram shows it that way.
Tim

heatboy_2

You have to return water.....

..... back to the tank and the cold side of the mixing valve.

Gary_27

Watts mixing valve

Tim, I was having the same type of problem. Hot water from the tank would back feed into the cold and whenever I opened a hot water faucet I would get a good dose of scalding hot water. The mixing valve I had did not have any checks in it. I bought a watts valve that has 2 checks built in and it did the trick....

Tim_59

Watts

Thank You.Do you know the part number?
Tim

Gary_27

Mixing Valve

Series MMV-M1 is the one I have.

Tim_59

Here is a quote from watts antiscald valve guide . I think I need to use an adjustable aquastat. I used a fixed taco unit. I don't think it is sensitive enough for this application.

"Aquastat - An Aquastat must be used to control the on/off
operation of the circulator. The Aquastat is set 5°F to 10°F lower
than the mixed water outlet temperature of the tempering valve.
The circulator cannot be allowed to run continuously because
bypass through the mixing valve will eventually allow the temperature
in the piping to climb to that of the hot water heater during
no draw periods."

Tim

Tim_59

Overkill


Electronic adjustable aquastat from Johnson Controls.

http://www.houseneeds.com/shop/manuals/johnsoncontrol_a419bulletin.pdf