Main Vent and insulation ??'s

Rich Baker

Problem: the radiators on main 1# (I have three) heat slower if at all, then #2 and #3. After much reading on this site and Dan's book, I have determined that I need to replace my main vents and insulate my mains. One problem I have, is a space issue with the main vent on main #1. (see attachment) When my basement was finished (by the prior owner) very little space was left around the main vent on main #1. The existing vent looks like a Gorton of some variety (Smallish and round) and is mounted at the end of the main on a 90 deg elbow that goes to the return; no nipple. In addition to the lack of side clearance, the distance from the top of the elbow to the ceiling is only 8.5". So my first question is can I install a Hoffman #75 or other main vent horizontally? This would allow me to use say a 4" nipple and a elbow. Alternatively could I use a Hoffman #4 on a 4" or 5" nipple (better then none)? I understand the Hoffman #4 only closes on steam not water.

The next question is what is the best type of insulation to use. My plumbing supply has only 1/2" fiberglass with a plastic cover. I think 1" or thicker would be better. Not a lot of clear info on this subject. Any thoughts on thickness, material, manufactures, and suppliers would be greatly appreciated.

Rich

Steamhead

That's a Gorton #1 vent

There's no advantage to using a Hoffman #75, it vents at the same rate. And the #4A (successor to the #4, and it does close against water) is smaller than that.

Measure the length and diameter of each main and tell us what vent is on it. We can tell you what you need from this info. Also you'll want to insulate those steam mains- this will really cut your fuel consumption.

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Rich Baker

Main Vent question and insulation size.

Steamhead; thank you for your response. All of the mains are 2” branches are 1". Main #1 is about 45', Main #2 is about 46' (this main has a main vent, not sure what kind not a Gorton or a Hoffman, that will spit if the system runs for a long time. Only 1/3 of this main is insulated, but is not having any problems heating the radiators evenly, my problem is with Main #1.) and Main #3 is about 20' I don't think Main #3 has a main vent but only serves 2 48" radiators, which heat evenly.

The reason I mentioned the Hoffman #4 is that I saw it at my local plumbing supply. It is also very short, about 2" tall.

Any thoughts on Insulation.

Steamhead

Main Vent Sizes

Mains 1 and 2 should get Gorton #2 vents, which are much faster than the Gorton #1. But you can put your Gorton #1 on Main #3 and it will speed up that main to match the other two with their Gorton #2s.

The Gorton #2 has its own little riser built in, so you can get away with not putting it on a nipple. It should fit in the space you have. Oh, and any vent you use should be installed vertically.

The Hoffman #4A is a very low-capacity vent that I only use on very short mains. I remove these much more often than I install them, as most of the ones I see are woefully undersized for the mains they are on.

The best insulation to use is fiberglass, with walls 1-inch thick. It is made in tubular sections 3-feet long that fit around the pipe. You may have to use a contractor for this, typically the sizes you need are only found at wholesalers.

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Rich Baker

Thank you....

Steamhead, thank you for your advice. I will follow it. Between business trips hunting it will be a few weeks before I get around to making the changes, but I will let you know the outcome, when I do.

Rich