Baseboards emiting heat while zone is OFF

JAlm2018

Hello everyone, been having this issue for a long while with my oil burner hot water system. (Pictures will be included of all) Its a 3 zone system(attic, main level and basement) with a oil fired thermo-dynamics s series boiler thats maybe 15 years old. Ive owned this house for 5 years and about a year or 2 ago, I noticed my attics baseboard heaters were hot and the entire attic reaches over 84 degrees F when set only to 70. I checked the thermostat and switching relays and the zones were not calling for heat. I also felt the hoses after the circulator pumps for the affected zones and they were not hot. After observing things even further Ive found that the basement zone experiances the same issue. The main level is not affected. I also found heat is coming up from what I assume is return side of the zones past the valves so I shut the valves off and the baseboards emit no heat. Is there a one way check valve or some sort of valve causing this? Im a auto/diesel truck technician combat vet having issues financially but very hands on diy guy so I know im more than capable of repairing this myself, just lack the knowledge. I would really appreictae any help, even though no one lives on these levels, Id like to use them in the future. Thanks in advance.

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Ironman

You got a flow check valve(s) that are sticking open and allow flow from the other zones to circulate through the one(s) that is overheating.

JAlm2018

https://forum.heatinghelp.com/discussion/comment/1807716#Comment_1807716

So would you happen to know where exactly that flow check valve is located in those pictures, or is it internal to the boiler itself?

bburd

You have three zone circulators. The one on the far right says "IFC" which means it has an internal flow check. These are not foolproof and can develop problems. However, the "IFC" label is not visible on the other pumps and I do not see any external flow checks on the system. If it worked correctly at one time, all of the pumps may have IFCs but one or more may not be working correctly.

It appears that you are getting ghost flow back up the returns to the zones that are too hot when they shouldn't be.

JAlm2018

https://forum.heatinghelp.com/discussion/comment/1807720#Comment_1807720

So if its getting ghost flow in both the basement and attic zones, the culprit would be the far right circulator whoch is the main floor zone. If i swapped the circulators between lets say the main floor and basement, would i be able to tell by running the heat and see which zones get ghost flow?

bburd

The main zone seems to be working fine, because when it is off there is no ghost flow there. You are most likely getting ghost flow in the attic and basement zones because the flow checks in those zones are either missing or stuck open. This will cause them to get flow when the main zone is running. So the place to look for trouble is the attic and basement zone flow checks.

Ironman

The flow checks are in the pump housing. Taco originally put them in the suction part of the volute then move them to the discharge flange after they saw that was a better placement.

I don’t see any isolation valves on the discharge lines, so you have to drain the system down to access them.

Grallert

Those two pumps on pex loops might not even have flow checks. Check to see if the labels say IFC anywhere. It could be as simple as replacing the two 007 taco pumps.

EBEBRATT-Ed

Or install regular flow checks which may be cheaper than replacing the circulators. But if the circs are 15 years old you might be better off replacing them with new ones with check valves and keep the old ones for emergency spares.