Basement radiators are hot when thermostat is not calling

riny

I have 3 zones: first floor, second floor, and a basement zone which was added later. Each zone has its own thermostat and circulator. The basement has two big cast iron radiators, and I've noticed that they're always pretty hot with the air temp around 60, even though the basement thermostat is set to 50. I verified that the thermostat is working correctly and is not calling for heat when it's not supposed to. (A previous owner used part of the basement as an office, but we don't currently use it as living space, and don't want to be wasting heat down there.)

The basement circulator is the green one on the right, and there's a Flo Control valve on the supply side. The other two zones have older Flo Control valves as well.

I thought the Flo Control was supposed to prevent unwanted circulation in the basement zone. Is that valve not working correctly?

mattmia2

is the handle turned fully clockwose on the flow check? could turn off that ball valve if you don't use that zone. there can be flow in both directions in a pipe under some circumstances so even if the flow check is working you could possibly get some gravity flow.

any chance there is a valve closed between the returns and the boiler that is forcing flow through those zones or something?

gravity flow on the same level as the boiler is harder than on a higher floor so it is a little less likely to be gravity flow vs somehow being forced by the other zones.

riny

Thanks, I'll check and make sure the handle is turned all the way. It's pretty rusty but hopefully I can get it to spin a little. I don't want to close off the basement zone entirely because we do use it every once in a while, and I like having it for freeze protection.

Interesting about water possibly flowing in the other direction. You're looking at all of the returns there and I don't see any way that's possible, but I'll look again tomorrow.

Intplm.

The zone in question has 'two big cast iron radiators". The thermostat is working properly. Do what @mattmia2 suggests. If that shows no change remember that a large cast iron radiator does not cool quickly. They tend to stay hot for a long time. This is what might be occurring. They may just be staying hot.

hot_rod

if it has worked in the past, look for something holding the flo check open a small amount.

If it has always over-heated it could be a case of forward or reverse thermosiphoning. Driven by the buoyancy of the hotter water.

The concept behind gravity distribution systems.

From Idronics 19

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