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frozen supply valves

The valve on 2 cast iron radiators are frozen and cannot be turned. There is no hot water getting into the radiators.
These are located near the thermostat and the furnace is running too much. I am reluctant to put a wrench on the valves cause if any leeks should occur it would cause a mess. I also do not want to drain the whole system down. Is there any easy fix that I can do with confidence?

Re: frozen supply valves


You were probably wise not to touch it before getting more info.

As soon as you touch a frozen valve you have to expect that there will be problems.

It would depend on your abilities & experience in handling plumbing problems---whether you can solder, or whether the valves are compression (screw-on) fittings, etc., or if it will loosen without leaking if you turn the stem with a wrench--often both sides of the rad have to be loosened so there is enough room to remove the bad valve.

Try applying lots of penetrating oil/WD-40 on the valve, let it sit overnight and see if the oil makes a difference.

There's no need to drain the whole system, but you WOULD have to shut down the boiler, shut off the water supply to the boiler, drain a gallon or two from the boiler drain, & open the rad bleeder valve to let air in to drain the water out of the rad.

You can then work safely on the valve.

Such jobs are best started in the early A M so there is time to get the new valve & get the system running by late afternoon.

Such valves are only available at plumbing supply stores, so you would have to be able to tell them the exact measurements, or take the old one with you.

When the valve is fixed, you would have to re-open the boiler water supply, bleed all the radiators to get air out, and click the on switch to the boiler.

There's no guarantee the problem is in the valve--it may be actually stuck in the OPEN position and it's sludge or an air pocket in the piping that's causing the lack of water circulation/lack of heat.

Decide if you want to diy or call a service person & post back.

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