Perhaps a stupid question...

The ON / OFF valve on one of my 1900s radiators does not turn. Pictures below. The radiator is in a permanent "hot" state.

Is the "valve" (handle and "small nut") indicated below a replaceable part? Or must I replace the entire pipe elbow + valve to replace the valve?

The small nut turns easily with a pipe wrench. I have not tried unscrewing it fully so as to not create a (possible?) geyser...

The boiler/radiators are off. If the valve is replaceable, will I be able to simply unscrew it and replace it (without all the water spraying out, without draining, etc.)? If not, can this individual radiator be drained sufficiently by itself? Or must the entire building's radiator system be drained?

I will explore finding a way to turn the handle, and re-use this valve. But assuming that's not possible, what are my options?

All images: http://imgur.com/a/Ar8iU

Radiator Valve

  • Steam or hot water? Does the radiator have one pipe or two?
    – hobbs
    Oct 7, 2015 at 4:32
  • @hobbs Hot Water, two pipes.
    – pkamb
    Oct 7, 2015 at 17:49

2 Answers 2


I have lived with hot-water heating for 70+ years. I have never seen this valve used. I have been strongly advised to never touch them, since the packing washer will have hardened decades ago, and turning the handle (if possible) could produce a permanent leak out of the system around the stem. All my systems have been one boiler-one circulating pump, feeding all the radiators, and one thermostat to switch the boiler on/off...

If you chose to remove the valve, you will need to shut off any make-up water supply, and drain all the water from that part of the system at or above the level of the radiator valve.

It is quite likely that you will need to loosen the large square fitting to access the washer that shuts off the flow of water through the radiator.

  • Thanks. You never turn off your radiators, then? On the 5 other radiators in the house this handle works find and turns the radiator on/off. Trying to service this one to do the same.
    – pkamb
    Sep 25, 2015 at 22:54
  • Never touch them; just the air-bleed valves at the top of each radiator 13 in my two-storey Toronto, Ontario, 1920's home
    – DJohnM
    Sep 25, 2015 at 23:08

Steam systems are typically black iron pipe. The valves may be brass or iron. The steam systems in my area, northeastern U.S. are at the least 60 years old. Most of the original valves are likely inoperative by now. The systems require little maintenance with the exception of the boiler itself. I was taught the valves should be open or closed, never halfway. The amount of heat to the radiator is controlled via the steam trap speed control. The little chrome device controls the speed at which the air escapes from the radiator. The steam can't enter until the air gets pushed out by the steam pressure. Each radiator is adjusted to balance the system. The radiators furthest from the boiler vent fastest, the ones closest to the boiler vent slower. If adjusted properly the radiators should heat at close to the same amount. There is some minor repairs to the valves, such as repacking or tightening the stem nut. Any attempt to replace the valves can quickly turn into a nightmare for the uninitiated or unprepared. The valves are typically stuck onto the pipes. Large pipe wrenches and possible a large hammer are required. The forces can result in new leaks elsewhere in the system. If the valves are open and not leaking I would leave them alone.

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