can i reduce a 1 1/2" steam valve to smaller TRV?

rhodebump

I am replacing the shutoff valves for several radiators that are 1 1/2 inches. It's a 2-pipe system, Weil McLain LGB-11

I was thinking of going with a TRV, but I can't even find anything that is 1 1/2 size. I do see a 1 1/4 size.
Would this be okay to do?

Could i even just reduce it down to 1"? Is there a rule that I can use to understand what I can do in terms of reducing steam coming in?

Steamhead

What type of system is this? Post some pics of the radiators in question...................

Danny Scully

1-1/2” for a 2-pipe system? Could be 2-pipe air vent?

mikeg2015

Might have been a vapor system. You need oversized pipe for vapor... whether 1 or 2 pipe. Condensate in 1 pipe really is a minimal amount of volume. It’s just a trickle of water. A 250k BTU boiler is making less than 0.5 GPM of condensate spread over a dozen radiators.

rhodebump

Here is a picture of the radiator and a picture of each side.

2 pipe, shutoff valve on the intake, a steam trap on the tail end.

rhodebump

here is a pic of valve before i took it off

Jamie Hall

Problem. That valve you removed is matched to the spud in the radiator; you can't replace the one without replacing the other. The new valve -- of any size -- will come with a matching spud. What you have to do is somehow get the existing spud out of the radiator -- which is much easier said than done -- and install the new spud. You may need bushings to reduce the radiator thread size to the new spud.

Yes you can go down to 1 inch. I wouldn't go smaller. Not sure if TRVs come with the necessary matching spuds...

SuperJ

I thought you put TRVs on the vent of a steam radiator, not the steam pipe. But I'm not a steam guy.

ChicagoCooperator

SuperJ said:

I thought you put TRVs on the vent of a steam radiator, not the steam pipe. But I'm not a steam guy.

That's for one pipe steam - this is a two pipe system where you put it on the inlet (in other words, there is no vent on the radiator in this circumstance).

Jamie Hall

I might add to my previous comment -- you will find that adding TRVs causes the boiler to see less radiation when they are closed. This may lead to some short cycling on the boiler. Further, a TRV on a steam system can reduce the heat output of a radiator -- by turning off the steam -- but it can't increase it.

Is this a balance problem? Because if so, and it is desired to have these radiators simply produce less heat, the solution is simple: partly close the inlet valve. That works just fine on two pipe steam.

EBEBRATT-Ed

Find the EDR of all radiators you want to put TRVs on. Find the steam pressure you will run at. Then size the TRVs with the MFG help if need be.

The right size will work a lot better. I would suggest Tunstall Associates in Chicopee, MA. Google them