Replacing radiator vents

eappleton

Hi all,

It's been a few years, but I'm jumping back into the steam world to try to get our coop's heating system (one-pipe) running more efficiently. I got some great advice when I was here before, but wasn't able to follow through at the time. I wasn't able to convince the building to put out some money to add venting on the mains. I did add two Gorton #2's on one main that was already vented. This helped balance the heating quite a bit, so I'm looking forward to seeing what two or three more candelabras will do.

Things have changed and I now realize that I can do the work myself, especially since I have a friend up the block who has tapped and added venting on the mains in his building. We're planning to tap and add venting soon, maybe during heating season! Seems a little scary to me. Anyone here done that?

The main reason I'm posting now, though, is that I would like help sizing radiator valves. The board has agreed to buy radiator valves for everyone in the building (24 units). I would like to make sure that everyone has the same brand (Gorton's, probably), sized correctly for each radiator. I know there are a couple ways to size radiator valves. I'm planning to use the method Gill and Pajek describe in their booklet, Balancing Steam Systems... (http://www.gwgillplumbingandheating.com/webapp/p/236/balancing-steam-using-a-vent-capacity-chart), whereby I would choose the valve based on the radiator size (and the pipe leading to the radiator), maybe adding up a little for radiators a long ways from the boiler.

I can't figure out how to choose the right valves, though. Let's say I'm going to choose valves for the three radiators in our apartment.

(two radiators)
37" high
8" deep
6 sections


(one radiator)
22" high
8" deep
5 sections


Do I need to estimate the EDR of each radiator and choose a radiator valve accordingly? Or is it about estimating the amount of air in the radiator, plus the pipe leading to it and determining the venting that will clear it in, say, 3 or 4 minutes? I'm at a loss. I can see why people size valves based on distance from the boiler. It's a lot easier. By the way, we're on the 3rd floor, with the boiler in the basement directly below us.

I also want to make sure that the risers in the top floor apartments are properly vented. Should I estimate the length of pipe to the boiler, estimate the amount of air that needs to be vented from the pipe under 2lbs. of pressure and then... ?

By the way, I understand that venting the mains is very important and that messing with the radiators won't solve any problems until that is taken care of.

Thanks all,
Eric

BobC

In general you want to vent the mains (and any express mains) very fast, and the radiators slowly. My understanding is it depends on the total amount of air in the radiator and the pipe feeding it. There is always an outlier that needs more or less than it would seem it should.If there are express mains they should probably be vented as well, that will make the radiator venting a bit more uniform.

How many radiator vents are we talking here (50, 75?), guessing can be expensive. I have used Maid o Mist vents for the past few years and been happy with them. They have one kit that costs about 2/3 as much as a single Gorton but it contains 5 orifices (4,5,6,c,and d); this makes tuning a lot less expensive if your not sure which one to use - Maid-O-Mist 0220-5L

I've only been using them for 3 years so I can not say how they compare with Gortons as far as longevity goes.

Bob

nicholas bonham-carter

Certainly BobC has hit the nail on the head, in stating the need for generous main venting. Two Gortons are not going to handle the needs of a seemingly large system as you must have.
I have a 1,050,00 btu boiler, with a total of 18 Gorton #2's, on six dry returns. As steam rises, the air leaves at less than one ounce of pressure.
Contrary to the Gorton website advice, the main venting must provide zero resistence to the air being pushed out of the pipes as steam rises, and the radiators must have a higher resistance. The theory that the distance from the boiler can enable all the air to be removed by the radiators is ludicrous!! They make very good vents, but unfortunately do not show their use well at all, on the website.
In your case, with a multi-family building, I would suggest first getting the main venting up to scratch, and then perhaps increasing the radiator vents on the top floor, as you see how a few may lag behind the others.--NBC

nicholas bonham-carter

I see that you already have the most appropriate Hoffman radiator vents, so those replacements can be taken out of the equation--NBC

BobC

NBC is right about those Hoffman vents, they are a well made vent. The 40's are slow vents (between a 4 and 5) and could work well for the lower floors. If you have 1A adjustable vents be warned they are difficult to adjust correctly, too much slop so you never know where you are unless you fuss with them.

Bob

eappleton

Thanks, Bob and NBC. We have 24 units, so it will probably be about 60 vents. Maybe we could get 1/2 Hoffman 40s for the lower floors and 1/2 Maid-O-Mist adjustables for the upper floors. Actually, two out of the three Hoffmans in our apartment are hissing through most of the cycle. I was thinking they were shot, but I might pull them off and soak them in vinegar. They're about 5 years old, I'd say.

I'm hoping to buy the vents before the mains are vented, because the building (a coop) has some extra money now and we want to spend it before we get taxed on it. I could wait to install until after the main vents are done. By the way, are express mains different from regular mains? I'm not familiar with the term.

We're going to start working on the vents soon. Have either of you tapped into a main during heating season? From what I've heard, it can done pretty quickly, though I'm worried about something going wrong on a cold day.

Eric

nicholas bonham-carter

Replace the main vents first, and you will see that the hoffmans are probably in good shape, unless killed by high pressure.
Don't forget to install a low pressure gauge, and vaporstat.--NBC

rrwitherspoon

Slow down and do one thing first.Vent main vents fast first
Add Gortons 1 or 2 to main vents. Location and configuration of main vents important. Gorton 2 need lots of head room Next step boil individual radiator vents in vinegar and water.
Then assess radiators especially those far from boiler for heat

eappleton

Thanks for the guidance. We'll start with the main vents first and then move to the radiators.