Old Hoffman quick vent air float

KellyAnn

Should I replaced this or can a fix it? I don't think it was working last winter due to the radiators not heating all the way across. I have a two pipe system without individual traps.

Jamie Hall

Two pipe without individual traps? Could you post a picture of the inlet and outlet of a typical radiator? I'm thinking a vapour system of some kind... in which case, you really need to have a vapourstat pressure control, set at about 7 ounces cutout.

As to the radiators not heating all the way across -- that could be one of several possibilities. One being that they may not need to... if the space is comfortable, they're doing just fine. Or it could be that the cycles per hour setting (newer thermostat) or anticipator is set for too short a cycle.

Or it could also be that that vent is stuck shut. It is an antique... you could try to unstick it -- some have suggested immersing it in vinegar for a while -- but you could also replace it with a Gorton #2 and be happy.

Steamhead

@KellyAnn , that vent is pathetically small. It was fine for coal firing but way too slow for oil or gas.

Looking forward to pics also. Where are you located?

KellyAnn

Jamie Hall

Vapour system, possibly Mouat. You need more main venting -- but it has to be located correctly. In these systems all the venting goes at the ends of the dry returns. Usually, the dry returns all come together at or very near the boiler, and then drop down to the wet return. Where they drop down is where you want the main venting. You should also check out on the steam mains. At the ends of the steam mains, there should be a crossover trap which connects the steam main to an adjacent dry return -- and very often both the steam main and the dry return will have a drip to a wet return at that location. It is essential that those crossover traps be working! Also, it is essential that the wet return at those locations be below the water line on the boiler.

Now also. Those systems run at very low pressure. The boiler must be controlled with a vapourstat -- not a pressuretrol -- which should be set at 7 ounces per square inch cutout and 3 ounces per square inch differential.

Can you post a picture of the boiler and the near boiler piping, and the controls? We can comment further...

dopey27177

Repairing the Hoffman Vent should be tried first. If it does not work replacement of the of the vent is needed. Using a Gorton #1 or #2 will work fine.

Looking at the radiator valve what stands out is this valveis an adjustable valve. This valve was the precursor to orifices installed in the radiator to limit the flow of steam into the radiator.

As far as the radiators heating partway across the heating element it is rare that they will heat all the cross. The full measure of steam filling the radiator will occur when you get into the single digits of outs side temperature.

As was stated this system is a vapor system and should not operate above 7 to 8" of steam pressure. To accomplish this a vaporstat needs to be installed.

Set at 4" steam pressure to start the fuel burner and 7 to 8" shut off.

As to the location of the Hoffman vent it placed just right. This system was designed by Hoffman and worked for may years.

Jake

KellyAnn

mattmia2

Was that like some of the last aircell made?

dopey27177

The old air cell covering had some asbestos in it. This was the cheapest insulation on the market.

Oh,I noticed that the boiler piping connection is lacking a Hartford loop.

KellyAnn

The cells are asbestos free we tested them before we purchased the house

mattmia2

I might have someone independent of the real estate and home inspection industry test it before disturbing it. Maybe someone here knows what it is. It looks newer than the last uses of asbestos pipe insulation, but I can also see how someone could have just replaced the last couple fittings and nipples on the supply and return without disturbing the insulation. The energy guide program is newer than the last uses of asbestos so that boiler is newer than aircell asbestos insulation.

I just don't know what else it could be made out of other than corrugated asbestos paper.

Steamhead

dopey27177 said:

Repairing the Hoffman Vent should be tried first. If it does not work replacement of the of the vent is needed. Using a Gorton #1 or #2 will work fine.

Looking at the radiator valve what stands out is this valveis an adjustable valve. This valve was the precursor to orifices installed in the radiator to limit the flow of steam into the radiator.

As far as the radiators heating partway across the heating element it is rare that they will heat all the cross. The full measure of steam filling the radiator will occur when you get into the single digits of outs side temperature.

As was stated this system is a vapor system and should not operate above 7 to 8" of steam pressure. To accomplish this a vaporstat needs to be installed.

Set at 4" steam pressure to start the fuel burner and 7 to 8" shut off.

As to the location of the Hoffman vent it placed just right. This system was designed by Hoffman and worked for may years.

Jake

@dopey27177 , I don't think that's a Hoffman system. Unless the remaining radiators have traps, it looks like an Orifice Vapor system that just happens to have a Hoffman vent that someone put on.

Assuming this is correct, the Vaporstat becomes even more important. This is because the only thing keeping steam from entering the dry (overhead) returns are the orifices built in to the radiator shutoff valves. As long as the pressure doesn't get too high, the orifices will meter the steam to only the amount that each radiator can condense. But with a standard Pressuretrol rather than a Vaporstat, the pressure will rise past the point that the orifices can do their job.

I'd replace that Hoffman vent with a Gorton #2. This would probably mean removing some of the bushings that Hoffman #6 vent is screwed into.