Hydronic Forced Air Heat Question

[Jerry Simon]

I normally see a zone valve to open and close the water supply pipe to the furnace heat exchanger for such. The building boiler wasn't on, so couldn't check the heat, but is this valve (?) a control for turning on and off the water to the exchanger? It's on a line marked as a *return*. It rotates about 180 degrees total, and has markings 1-5.

If it ain't a valve, what is it, and what is it for?

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[Bill Kibbel]

TRV - thermostatic radiator valve. They're intended for folks to add to individual radiator supplies in rooms that get too hot. That way you can "balance" the heat distribution (rather than the double-hung method). Many apartment buildings with central boilers have them. Every room in every old place I've stayed in the UK has them.

[Jerry Simon]

TRV - thermostatic radiator valve. They're intended for folks to add to individual radiator supplies in rooms that get too hot. That way you can "balance" the heat distribution (rather than the double-hung method). Many apartment buildings with central boilers have them. Every room in every old place I've stayed in the UK has them.

Thanks, Bill. But used in conjunction with a hydronic, forced-air system???

It's not located at the supply line for the exchanger, nor at the return line at the exchanger, but below the furnace, on an extension of the return line.