Hoffman 500 and 508

Jim_80

Thanks, Steamhead. You are correct, the 500 series do have that fabric that expands when wet.

Good to know that they have inconsistent performance. I actually have some varivalves, but even they are too large for one of the rads. Water leaking onto the floor isn't too big of an issue, but something I'd prefer to avoid.

Anyway, I'll take some photos of the radiators in the next day or so and post them. Right now the radiators have hot water bleeder valves on them, so they don't work at all. I don't know who put the wrong valves on, but they're also so encrusted with paint they wouldn't do anything even if I could open them up.

Jim_80

Hoffman 500 and 508

I have a one-pipe system that has ceiling-mounted radiators in the basement. These rads have been turned off for at least 5 years, but I now want to turn them back on.

Problem is that a normal Hoffman 40 vent can't fit into the space (b/c the rads are mounted so close to the ceiling). I have about 1" between the vent port and the ceiling.

Someone I spoke with at a local plumbing supply company suggested Hoffman 500 or 508 vents because they are very small. Will these work with single-pipe steam?

Thanks.

Steamhead (in transit)

If those are the ones I think they are

they are "hygroscopic" which depend on moisture causing some fabric to expand, which closes the vent. These vent rather slowly on steam, when they work at all.

The shortest non-hygroscopic vent I know of is the Heat-Timer Vari-Valve, which usually vents too fast unless you close the shutter most or all the way. Also, it doesn't have a float inside it so if the system floods with water, it will leak onto the floor. But if the basement is unfinished that might not be much of a problem.

Maybe the clearance problem is a result of the vent being installed in the wrong place on the radiator? Take some pics and post them, let's have a look. What vents are on these rads now?

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soot_seeker_2

What about...

...if the ceiling is finished, poke the vent through the Sheetrok or plaster. If the area is obstructed by a joist or something you can go around, pipe the vent to another location using a 1/8" street el.

Or, as Steamhead suggests, drill and tap another hole somewhere else on that radiator for a vent.

Yhis thing must have worked somehow at one time, and back then I'll bet steam vents were bigger than they are now.

Indeed, post a picture.

Long Beach Ed