Need for steam radiator shutoff valves?

ScottSecor · June 2019

We typically call them angle stops in my neck of the woods. I often wonder if we actually need angle stops on steam radiators? I'm talking about your typical house built in 1919 with one pipe steam. I have never owned a home heated with steam, but I've worked in well over a thousand. For those of you that own this type of house, do you ever shut the valve to your living room radiator? How about the bathroom? I realize that in some cases the in-laws show up at your door Christmas Eve and you might sneak upstairs to close the angle stop in the spare bedroom so they don't stay too long.

I often question the need for a angle stop when we're modifying a steam system. I'm sure others will recall how difficult it was tightening that union on the angle stop when the new recessed Sun-rad style cast iron radiator was just installed. On a few occasions we simply used a black malleable union instead of a shutoff valve and things worked out just fine.

With regard to the angle stop, I suppose the brass valve body, union and spud has a little give to it. I suppose the built in ninety degree fitting with union makes some sense since practically every riser we encounter comes up out of the floor. If you have finally decided to have your hardwood floors refinished after a hundred years, I guess you'd be glad you could just shut off the valve, oh wait, it doesn't actually shut off anymore....

Please share your thoughts.

Jamie Hall · June 2019

Seems to me that they are really there more for convenience when servicing the system -- since they almost always leak a bit and give problems! Maybe when they were new...

Two pipe is another matter -- there you can use them to throttle the radiator without troubles.

Steamhead · June 2019

The original reason was when boilers were coal-fired, you couldn't just shut the coal fire off to change an air vent or something on a radiator. So shutoff valves were installed to isolate the radiator for such repairs.

With oil or gas firing, you just flip the switch, wait a few minutes until the steam goes down, and you can start work.

STEAM DOCTOR · June 2019

The valves are always smaller internally then the pipe. If you remove some valves and leave others, there is always a risk of throwing things a bit out of whack. Not likely but could happen. Ideally, no one pipe system in a single occupant home ,would have shutoff valves. Two pipe or apartment building might be different story. I would prefer 1"/8 ball valve leading to the air vent when shutoff ability is needed. Just my 2 cents

ScottSecor · June 2019

Thanks for the replies, glad I'm not the only one that thinks this way. Steamhead, I forgot that many (perhaps most) of these systems were in fact coal fired when new, that makes sense. Sometimes I forget that we're talking about steam systems that were installed a century ago.

EBEBRATT-Ed · June 2019

Many times things are installed that are not needed.

How about a 1 zone hot water system or a hot water system with multiple zones with zone valves. How many of those systems have unneeded flow-checks?

Just because someone thought they didn't look right without them.

One pipe radiator valve usually wont close tight if you wanted them to so there useless. Two pipe is different as @Jamie Hall pointed out

Jakek · June 2019

Could replacing a valve with an elbow be a possible solution for minor water hammer problems when the riser is slightly undersized anyway?

Fred · June 2019

Jakek said:
Could replacing a valve with an elbow be a possible solution for minor water hammer problems when the riser is slightly undersized anyway?

Nope, if you have water hammer, you have water pooling somewhere. Check the pitch of the radiator. If the hammer seems to be coming from under the floor, raise all four legs of the radiator a 1/2" or so and then repitch the radiator. It is possible a horizontal pipe under the floor has lost its pitch.

Jakek · June 2019

Thanks @Fred To be more specific, if the radiator is at the correct pitch and there's sloshing in the radiator when the system nears full pressure, is it possible the slight reduction in diameter introduced by the valve could be part of the problem and thus removing the valve entirely could help resolve the problem? (The valve remains is fully open.)

Still trying to wrap my head around everything.

Fred · June 2019

@Jakek , if you hear water sloshing in the radiator, it could be a couple things:
- The radiator isn't pitched enough
- The system pressure is too high and the steam pressure isn't allowing the water to get past it to return. Make sure the system pressure is around 1.5 PSI max. If you don't have a 0 - 3 PSI gauge on the boiler, get one and install it. The 0 - 30 PSI gauge is useless. Also make sure the Pigtail that the Pressuretrol is mounted on isn't clogged. If it is, even if it is set correctly, the Pressuretrol can't see the actual pressure and shut the boiler down at the 1.5 PSI range.
- How "under sized is the valve and supply pipe? If it is too small, it may not have enough room in it to let steam in and water out simultaneously.
- Make sure the disc in the valve is not broken off and laying in the bottom of the valve. If it is, that will block/prevent water from draining.

Jamie Hall · June 2019

Probably not. Hammer is rarely from the water remaining in the bottom of the radiator -- if the valve is fully open. Which can be a big if. Are you sure that the disc on the valve hasn't come adrift and is partly blocking the opening?

ethicalpaul · June 2019

My dumb opinion is that the valve is totally unnecessary 99.9% of the time, and even then it's an easy workaround (as was said, just turn off the boiler, wait 30 seconds). Again, talking single family one pipe.

But having said that, the valve is probably the cheapest perfectly-sized combination elbow/union available so I will keep installing them on the rare occasions I need to in my house.

Intplm. · June 2019

I agree @ethicalpaul . I feel much better with a valve in place however.
When I need to repair or replace a old steam rad. the valve still comes in handy. If the valve is old, I will replace the valve with the new/replaced rad. . New ones do hold.
In a pinch you can even purchase one at one of the big box hardware stores, right off the shelf.

gerry gill · June 2019

Like Steamhead says, its really not a modern day necessity as the switch can be turned off to work on the system, but back in the day with the coal boiler...well, you can't turn off your bar-b-que if its char-coal.

Need for steam radiator shutoff valves?

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