Radiator Steam Valve Puzzling Issue

nuclear

I live in a prewar NYC building with steam valve radiators. I have an issue with one radiator where the steam valve does not open - unless I give it a small tap of the finger. That lets the steam floodgates open. I have to do this almost every time the boiler gets going. I have a second radiator in the room, and that one rarely has the issue. Sometimes it does as well, but most often not more than 1-2 times a month. The other radiators in my apartment don't seem to have the issue at all.

The weird thing is that the steam valve having the issue is completely new. It was just put in for the winter season. I don't know if this was an issue before since I just moved in a few months ago.

My question is - do you think this is an issue with the steam valve, the radiator, or ..something else. I find it strange that it's having an issue with a new valve and also a second radiator with different intensity.

Jamie Hall

Just answered under the other one -- but here goes again -- it's the vent. Not all vents are created equal -- and you tend to get what you pay for. What kind of vent (brand, size) is it?

nuclear

@Jamie Hall It looks like this Hoffman valve, but without the logo. Looks like a cheaper generic version

https://www.amazon.com/Hoffman-Steam-Angle-Radiator-401440/dp/B0057XTJOI

EBEBRATT-Ed

And the boiler pressure may be too high not allowing the vents to work properly

Jamie Hall

EBEBRATT-Ed said:

And the boiler pressure may be too high not allowing the vents to work properly

If that's what you got, it is a Hoffman steam valve -- currently made by American Standard but, I think, in China. They aren't bad. But note @EBEBRATT-Ed 's comment -- they -- and many vents -- may not open after they have been closed at more than 3 psi, without being "persuaded" to. It's true they won't fail -- to soon -- on higher pressure, up to 10 psi, but they won't function properly if subject to more than 3 psi.

nuclear

That's interesting. Does that mean that a valve with a higher pressure threshold could solve this issue e.g. one that has a maximum psig of 10, or do you think that will just prevent air from efficiently escaping if the pressure is lower than the valve is expecting e.g only meant for lower floors?

Jamie Hall

No. Misunderstanding here. The valve should be wide open when the system is cold. Then, as steam is produced, the valve will let air out of the radiator so steam can get in. If steam gets to the valve, the valve will close. Has nothing to do with pressure...

Nor floors. The steam pressure will be much the same on all the floors of the buildng

However...

They are somewhat delicate, and excess steam pressure may lock them shut -- if it doesn't destroy them completely.

EBEBRATT-Ed

@nuclear

If you download a chart for ven rite vents (or any mfg) you will find some information about vent oarfice size and "max pressure"

The vents with larger oarfices are usually rated for lower pressure that vents rated for high pressure