Thermostatic valves

Plumber7

I have a customer with a home built in the late 1800s. The radiators have two tappings on the bottom of the radiators but on the same side. (There are also capped 3/8" gas lines through the floor at each radiator) But that's another question for another day!!
There are no traps, or pumps on the system. I'm guessing it's a two pipe steam system, because....there are two pipes. I'm also guessing the system has no traps because the returns are all wet. Some rooms are overheating and the customer wants thermostatic radiator valves to control the overheating. Can I use the one pipe type of thermostatic radiator valve that is attached to the air valve opening, and you install a straight air valve into it. It stops the radiator from venting when temperature is reached. Any idea's out there? Thanks. Tom

clammy

3/8 gas line?

Are you sure that's a gas line take a good look and see if all the rads have this 3/8 line if so may be they where old vacume line and instead of trv how about graduated supply valves.Does the boiler have a vaporstat on it if it is steam i would install one this system is most likely a vapor vacume type.If you can't find graduted valves may inlet orfices could be the soulution and check the pressuretrol .I,ve seem a few of these types of jobs with the old vacume lines behind the rads good luck