Does a Taco mixing valve have a check valve in it to prevent the flow of hot water flowing back through the cold inlet side? The cold inlet feels as hot as the hot inlet. The mixed output feels about the same temp as the 2 inlets. I think the water is leaving the circulator on the hot input and flowing through the cold inlet instead of flowing through the mixed output through the floor loop. My thermostat is calling for heat and the circ is running but the room temp is down 3-4* and it never was before I added this mixing valve?
Taco mixing valve help
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I doubt it would have an internal flow check, but I don't know why you would need it. I have a Danfoss mixing valve for boiler return temp protection and it works without a check valve, I did add a ball valve on one inlet to regulate the flow into the valve. Can you post a diagram of your piping including the circulators so we can tell what you are doing? Mark from AHONA was VERY CLEAR that I must follow the instructions on the Danfoss accurately. It is easy to mix up the three ports on the valve. If your hot supply is less than the mixing valve, the hot should just flow through the valve. The valve will be uniformly hot through conduction. What is the temp of the "cold" pipe some distance from the valve? It is cool you do not have a backflow problem. It may be that your circulator is undersized for the head on the mixing valve. If your circulator was "just enough" before adding the valve, and/or if you stepped down a pipe size(or two), you may have altered your system flow where you existing circulator can't move the water at the flow you need.
Thanks for the replies. Bondo hit the nail on the head. You have to pull through the valve. Not push.
I have a 3 zone manifold, but have only been using 1 zone, basement gypcrete which I run 90* temps through....worked great. I installed a 2nd zone under main floor of house and need 150* temps for the wooden floor. So since I have the 3 zone manifold already piped, just add 2nd circulator, adjust already present mixing valve for 150*. I then added a 2nd mixing valve "AFTER" basement circ thinking I could mix from 150* to 90*. Circ would push hot inlet right through the cold inlet which took flow away from "mixed" outlet. Path of least resistance thing. So I added a check valve to the cold inlet side so hot couldn't flow through. It's better but still not right.
After reading the instructions of the mixing valve more closely, I concluded the circ has to be pulling from the mixed output for it to work. Not sure how a circuit using valves instead of circ functions properly by looking at taco instructions. Oh well. More repiping! Live and learn. With all the repiping though, I think I'll keep the 1-1/4" copper manifold and switch to pex after the zone stubs. Much easier to switch things around.
Thanks again for the replies.
I have a 3 zone manifold, but have only been using 1 zone, basement gypcrete which I run 90* temps through....worked great. I installed a 2nd zone under main floor of house and need 150* temps for the wooden floor. So since I have the 3 zone manifold already piped, just add 2nd circulator, adjust already present mixing valve for 150*. I then added a 2nd mixing valve "AFTER" basement circ thinking I could mix from 150* to 90*. Circ would push hot inlet right through the cold inlet which took flow away from "mixed" outlet. Path of least resistance thing. So I added a check valve to the cold inlet side so hot couldn't flow through. It's better but still not right.
After reading the instructions of the mixing valve more closely, I concluded the circ has to be pulling from the mixed output for it to work. Not sure how a circuit using valves instead of circ functions properly by looking at taco instructions. Oh well. More repiping! Live and learn. With all the repiping though, I think I'll keep the 1-1/4" copper manifold and switch to pex after the zone stubs. Much easier to switch things around.
Thanks again for the replies.
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