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john leonard
cast iron hot water radiator vavle leak

I have several radiators where the valve is leaking. It seems to be leaking around the valve stem or packing nut and has run down the pipe making it rusty. Is the valve bad or can I just tighten the packing nut? If I try tightening the packing nut what is the best way to go about it. Hot or cold? Valve on or off? Thanks in advance. I'd like to get this done before winter in the northeast.

Re: cast iron hot water radiator vavle leak


Unfortunately, just tightening the packing nut is usually not enough to solve the problem---since seveal valves are leaking, the packing inside the valve is probably shot on all of them.

Low-cost packing is widely available at the home improvement stores, as well as the plumbing supply houses.

This would entail draining about 1 gallon from the drain valve at the boiler, shutting down the system (on/off switch at the boiler) & shutting off the water inlet refill valve---this would prevent water spurting out of the valve when you try to service it---you could then remove the valve cap, replace the packing & replace the valve cap.

The process is reversed to put the boiler back in operation when you have attended to all the leaking valves in the radiator system.

There are numerous alternatives to consider with leaking rad valves--- if you are not using the valve anyway to modify the heat in the rooms, many people simply REMOVE the valves and solder in an elbow, or coupling if the connections are copper, or add widely available compression nipples (screw-on connectors) if those are what you have now.

New rad valves are available at plumbing supply houses, but they usually cost $35-$70 each, which is exhorbitant---another option is to put in a standard BALL VALVE for $5, either sweat (solder) or compression if you need control of the rad heat output.

Even another option is to install a TRV (thermostatic radiator valve) for heat control of the rad in a particular room ($35).

My experience has been that most people do not need heat control for the rads if the system is sized properly to begin with, thus, pulling out any problem valves is a good idea.

john leonard
Re: cast iron hot water radiator valve leak

Dear Nashuatech thank you so much for your quick response and solution. I will probably just replace the packing as replacing the whole valve gets into a whole Magilla. I would end up breaking the hot water pipe to the radiator as they have gotten pretty rusty from the constant leaks.
Thank you again friend.

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