radiator vent problem

Mike AK

Hey all:

I have a question about radiator vents. As I understand it, when the heat reaches the vent, the vent should close, and this forces the air to go into other less full radiators or to trip the pressuretrol and turn the boiler off. When the heat goes down, the vents open again. Is this right?

Anyway, here are my two problems. One: I bought a new Gorton #6, and it does not close at all when the steam reaches it, and so a lot of steam escapes (and if I put an old Hoffman #40 on the same radiator, it closes fine). Did I just get a bum vent, or is there a way to correct this?

Two: I bought a Gorton #5, and also a Hoffman adjustable vent, and these close correctly when the steam reaches them. However, they begin to let off steam as the pressure in the system builds. I thought this was because the pressuretrol wasn't working and the pressure was getting too high; but I just installed a low pressure gauge and the vents begin to let off steam when the pressure reaches about 3 or 4 ounces.

Is my understanding of how a vent should work off base? Or is this a sign of a bigger problem with the system? Or are my vents just not working very well (as I said, the ones that are not working are all new--the older Hoffman #40s that are on other radiators seem to be more dependable).

Thanks for any help or explanation,

Mike A.

Patrick Linhardt, \"Linhardt's Field Guide to Ste

vent operation

Hi Mike,

You are mostly correct. The vents close at steam temperature, open when they cool. That's a very simplified sequence of operation. If they don't close off when steam reaches them, they are not sealing off internally. This could be a bad vent or something like dirt on the seat that is preventing the vent to close off completely.

It is unusual to get that many new vents that are bad, and from different manufacturers. But your pressure sounds low enough and you aren't mentioning any release of water. Check the other obvious signs, valve wide open, pitch correct, etc.

Best regards, Pat