One zone heating - ghost flow

DeanG

Hello I have one zone that heats up without a call for heat.

The taco relay isn’t calling for heat and the taco circ pump isn’t running.

I replaced the circulator pump assuming the check valve failed inside the unit. Taco 007 model, but my issue persists. Specifically on this one zone and not the others. It happens when my boiler is heating domestic hot water.

Any words of wisdom?

Times are tough and money is short so I’m reluctant to call someone out again to hit me with a huge bill.

Thank you!

Big Ed_4

would suspect a bad mixing valve …

BDR529

Whats with all the mixing valves? 3 zones of radient?

HVACNUT

It's hard to see the piping. At least 2 low temperature zones.

Those are IFC circulators pumping down?

You could try a compression spring check on a vertical return. Though it's more of a Band-aid than an actual fix.

HomerJSmith

It seems to me that the pumps should be pumping away from the mixing valves not into it. Pumping away from the mixed port. More pics from further away would help.

Joe Mattiello

what changed in the system, or has it always overheated in that one zone? The check valve holds up to approximately.5 psi for obvious reasons, the pump discharge pressure has to overcome IFC to satisfy the zone. You can replace IFC only without replacing entire pump. It’s an off the shelf item. It’s one of your other zone pump overcoming the IFC check if you’ve done a physical inspection and no system debris hindering the check from fully closing allow water to go through that zone whenever one of the other three zones energize.

If it persists, to mitigate you can install an external check valve on the return where most of delta p eroded through pressure drop in that zone, or go with a zone valve as a positive shutoff. That will permanently stop flow. Hopefully this helps. Taco has a technical support team at 401-942-8000. They’re very knowledgeable and can offer additional support

hot_rod

Is there a boiler curculator in the piping we font see? How us the indirect pioed?

ghost flow is is often the return piping, feel that to see if it warms first, or is warmer than the supply side. some systems need supply and return checks, usually primary secondary piping , however

You should always pump away from the mixed outlet of a 3 way thermostatic valve, pulling the blend of hot and cold. I can’t see those valves working properly piped like that?

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