Odd vent, what to replace it with?

adamfre

Fired my system up for the first time, and one of my in floor radiators didn't heat up. Assuming a bad vent, but not sure what to replace it with? I'll attach a pic. Rad is 72 EDR.

Hap_Hazzard

Don't assume it's the right size anyway. How much air do you need to vent and how fast do you want to vent it?

There's probably some history behind how all those adapters got there, but the reason for the nipple is to keep it from spitting water. Judging from the amount of rust on the vent, fittings and spattered on the joists it didn't quite do the trick. Better use a vent with a float this time.

Steamhead

Ancient Hoffman #4. The modern direct replacement is the Hoffman #4A, which does have a float. Can't hurt to try one of these.

adamfre

@Steamhead, were the #4's originally a main vent? Which actually kinda makes since why it would be hanging off the end of my in-floor rads, being they are located at the end of each main. Maybe they were trying to kill two birds with one stone; vent the rad, and vent the main. I do have main vents installed now so would a smaller vent for the in floor rads be more appropriate now?
Sorry for all the questions, hopefully I'm learing!

Hap_Hazzard

They don't currently call the #4 a main vent, but you often find them used for that. I had one on a short fin-tube section at the end of one of my mains. Apparently they were trying to kill those same two birds.

If you look at the attached PDFs, the one with the "special steam vents" classifies the #3 as a "steam air line valve," the #74 as a "steam unit heater air valve," and the #4 as a "quick valve." Like they're not sure where to use it, but it's quick.

The other PDF shows the #4A. The application table indicates that it's a main vent for small systems.

Hoffman radiator vents typically have a 1/8" stem on the side, but they also make several models for convectors with the same size stem on the bottom. If you're going with Hoffman, that's probably what you want, but I'm pretty sure Gorton, Maid-O-Mist and others come that way too.