Radiant zone problem

eleft(retired)

open this, it might clear things up

al

HeavyP

radiant zone

I have a 3 zone boiler, 2 are baseboard 1 is radiant. They are operated by zone valves and one circulator. The radiant zone comes out of the zone vale into a 3 way mixing valve mixed with return water. The manifold is about 30' away, where there are 2 equal size loops less then 150' each. My problem is the water seems to be going through the mixing valve and returning into the boiler(bypassing the mixed port piping to the manifold). Do I need a check valve on the return water side of the three way mixing valve, or do I NEED to pipe the radiant zone as primary / secondary piping? Is there something I'm missing? Thanks in advance for the help.BTW the pump is a 007.Chris

Mark Hunt

If you could


post a picture. I am curious as to how a circulator is pumping into a 3 way valve. It should be on the "mixed" side of the 3 way valve, pumping away from the 3 way.

I'd like a look at the set up.

Mark H



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HeavyP

radiant

I dont have a digital camera, but the supply comes out of the boiler into a spirovent, then into the circulator, to three zone valves.

HeavyP

radiant continued

out of the zone valve into the three way mixing valve.

Unknown

Not enough pumps

If you do not have a pump pulling on the mix port and pushing into the radiant system, nothing will pull water from the cold port to the mix port. Nothing will pull water through the hot port to the mix port. The boiler pump is pulling water through the hot port and out the cold port and back to the boiler.

Without a circulator after the mixing valve, the pressure on the radiant system supply and the radiant system return is equal. Therefore, no water will flow through it.

Noel

HeavyP

would a check valve on the on the "cold" side of the mixing valve help this problem? thanks for all the help

Unknown

Check valves stop flow

in one direction. How is a check valve going to pull on the mix port?

If you don't have a pump on the radiant loop after the mix port, you have the same pressure on the supply and return manifold. Period. The flow would be only hot through the radiant loop, just like the other zones, if you put a check valve on the cold port.

The key to understanding it is this:The pump on the outlet of the mixing valve pulls the water from two loops at the same time, through the valve. One loop is the hot port of the valve, through the mixer, through the radiant,out to the boiler return, through the boiler and zone valve, and through the hot port on the mixer again.

The other loop is from the cold port, through the mix port and the circulator, through the radiant, and back to the cold port.

One pump on the radiant pulls these two loops at the same time. Without this pump, the cold port loop has no pump in it anywhere.

The boiler pump can move water through the hot port loop, but not the cold port loop. That will toast the thermostat in the mixing valve.

It will provide hot only water through that zone, like through the other zones.

Noel

HeavyP

ok

thanx noel