Motorized Valve Failure?

[Brian1]

I live in a building with common hot water pipes for radiators. My heating units have a thermostat that appears to be connected to a motorized valve (this one: http://www.sinro.cn/en/cp_view.asp?id=882).

I would expect that when I turn off the unit, or the temperature exceeds that which is set on the thermostat, the valve would shut and prevent more hot water from flowing through the radiator. This is not the case. Unless I close the manual shutoff valve, there is always hot water flowing through.

Does anybody know if the electronic valve might be malfunctioning, or am I making the wrong assumption?

Thanks,

Brian

[jadnashua]

Sounds like the valve is shot...a motor opens the valve, a spring closes it. So, when the power is removed, it should close on its own. Crud, corrosion, whatever could be holding it open.

[Brian1]

Thanks. Any idea of how big a job it is to swap out? Also- are these things available commercially at someplace like a Home Depot, or would I need to order?

Thanks for the help.

Brian

[jadnashua]

It depends on the brand and what's wrong with it (valve or motor). Some you can replace the motor without changing the valve, some you can't. Could be 10-minutes, could be an hour or more and the system would have to be shut down and at least partially drained then refilled and purged. You'd need to know what you have, and whether it is the motor (if separately replaceable) or the valve (or both). A picture might elicit more specific help. HD does carry some bits that might work, but more info is needed.