Weird radiator valves on vapor system

STEAM DOCTOR

Good evening. Came across these radiator valves on a job today. Apparently they are controls by the devices in the basement. The devices seem to be some sort of pressure control.I would imagine that the idea is for the radiator supply valves to shut off when the pressure gets to the setpoint. There is some sort of spring in the body of the radiator valve. Has anyone come across one of these? Is there anything to know about them? Proper settings, adjustability, historical info etc.

Thanks,

Aaron

STEAM DOCTOR

Copper tube

There is a thin copper tube that runs from the rad valves to the pressure controls in the basement. Probably to sense pressure and "communicate" with controls.

STEAM DOCTOR

Replacement

Can these valves be replaced with conventional radiator valves? The customer is having balancing issues. Adjustable valves would give the customer an ability to limit/increase steam inlet. Some of the valves have already been replaced with conventional radiator supply valves

JStar

Valves

Look like pneumatic valves. What is the name on the valve? Mergold?

STEAM DOCTOR

Mergold

Yes. The controls in basement are mergold. The valves on radiators are Power(I think,not sure).

Dave in QCA

pneumatic control

The valves, as has been suggest are pneumatic control valves. The normal configuration consists of a compressor that supplies air. It usually has a high pressure in the tank, but then goes through a pressure reducing station that sends out 20 psi to the building. These lines go to pneumatic thermostats. That action of the thermostat is to close the valve when the thermostat is satisfied. Actually, the old systems were usually two position, in that the thermostat clicked to either fully close the valve or fully open it. Now, most are modulation so that the valve throttles to maintain precise temperature control.



I don't know what roll the mergold pressure switches were set up to do. if there are no thermostats left, if there is no compressor, then perhaps the pneumatic control system has been ripped out of the building. That would be too bad because they really do work quite well, they are just a bit of a mystery to most handy men. If the guts of the system were ripped out.... that is there is no air pressure being applied to the valves, allowing them to remain in the wide open position all of the time.

STEAM DOCTOR

Valves

The only thing that I saw was the pressure control in the basement ( two of them actually). Some of these valves have been replaced with standard radiator valves. The copper tubing is still sticking out of the floor. I am assuming that there are no hidden pressure tanks. If there were then something should be coming out of the copper tubing(unless of course they were capped off somewhere). Is there any reason not to replace them with standard radiator valves?

Steamhead

They're "Mercoid" controls

I can't really see how they tie in, though.



If there is no compressor and tank, the pneumatic system was probably abandoned. Nowadays you should be able to substitute TRVs for the pneumatic valves and do pretty much the same thing.

Dave in QCA

thought so

I thought so too, but I could not see the letters stamped in the device and I thought there might be some other old manufacturer that I was not aware of. Thanks,

Dave in QCA

You can replace

As the system exists right now, they are just an open valve. The tube from the valve would go to a thermostat. If there are no thermostats, then you know the system is not operable. Like I said before, that is really unfortunate. But, as you describe the system, there are no thermostats and you can't even find where there might have been a compressor and tank.



Right now, you have open valves that cannot be closed. There is no reason that you cannot replace them with manual valves.