Main Vents Destroyed - Proper Replacement Suggestions

Unknown

is to change that reducing ell to a 2 by 3/4 tee and install the vent on the 3/4 tapping as high as you can get it . Then the main continues down horizontally past that tee and drops to the dry return . What you want to avoid is having the condensate slam right into the main vent and lower the life expectancy dramatically .

Short of that , you can pull those bad main vents , twist in a street ell , long nipple , ell , then the main vent . It's not the ideal location but it does get it away from the path of destruction .

Emmett McGuire

I have gone through about 4 pairs of main vents over the past 14 years. It doesn't seem to take very long before they start letting water and steam spout from them. (When the problem is steam, often clonking the vent with the handle of a screwdriver will cause it to close - until finally it doesn't). The only suggestion made to me over the years has been to make sure all the mains are properly sloped. This I've done to the best of my ability without much change.

I suspect the vents were originally installed the wrong way, the wrong place, and are quickly being destroyed by hammering water.

First, some background. This is a one-pipe system (one pipe to all radiators) but there is a double pipe in the basement for the two mains: two 2" iron pipe runs from the boiler - the first along the front of the house, the second along the back of the house. At the end of each of these is a 90 deg. elbow (reducing 2" to 1") connected to a 1" nipple that drops a few inches to another elbow connecting to a 1" return. My main vents are perched atop the reducing elbow at the end of the 2" supply.


I've attached pictures of the vents:

In the past few days I've read articles which say that the main vents must be place above the mains on a nipple and, preferably, "behind" (I'm not sure what that means).

The diagrams on HoffmanSpecialty.com ( http://www.hoffmanspecialty.com/pdf/submittals/hs-901a.pdf ) always show the vents placed on the return away from

Emmett McGuire

Main Vents Getting Destroyed

I have gone through about 4 pairs of main vents over the past 14 years. It doesn't seem to take very long before they start spurting water and steam. (When the problem is only steam, clonking the vent with the handle of a screwdriver will cause it to close - until finally it doesn't). The only suggestion made to me over the years has been to make sure all the mains are properly sloped. This I've done to the best of my ability without much change.

I suspect the vents were originally installed the wrong way or the wrong place (or both), and are quickly being destroyed by hammering water.

First, some background. This is a one-pipe system (one pipe to all radiators) but there is a double pipe in the basement for the two mains: two 2" iron pipe run from the boiler - the first along the front of the house (35 ft), the second along the back of the house (31 ft). At the end of each of these is a 90 deg. elbow (reducing 2" to 1") connected to a 1" nipple that drops a few inches to another elbow connecting to a 1" return. My main vents are threaded directly into the reducing elbow at the end of the 2" supply. The top of the mains are 13" (front) and 10" (back) from the ceiling, which doesn't leave much room for the vent.

The main supply slopes downwardly away from the boiler and the return slopes downwardly from the end of the supply toward the boiler.

I've attached pictures of the vents. Please note that until a few days ago, both mains were malfunctioning Hoffman 75's. When one front vent failed totally, I replaced it temporarily with the original Hoffman No. 4 vent that was on the system when I bought the house 16 years ago.

What can I do to make my vents work better?


In the past few days I've read articles which say that the main vents must be place above the mains on a nipple and, preferably, "behind" (I'm not sure what that means).

The diagrams on HoffmanSpecialty.com ( http://www.hoffmanspecialty.com/pdf/submittals/hs-901a.pdf ) always show the vents placed on the return (rather than the supply, as in my case) away from any turns/elbows.

Are my vents being clobbered because they are on an elbow?

Should they be put on a nipple and positioned further "upslope" along the supply?

Any and all recommendations are appreciated.

Thanks.

Big Ed

Vent

Reinsulate the supply steam pipe will help alot. Will help the whole system . Drop the water level to 1/3 of the glass gauge and drop the system pressure down. A Pressuretrol ??? Cut-in .5# diff 1#........

Steamhead (in transit)

Also

make sure the return lines aren't plugged, and that they both drop below the boiler's water level before tying together. If something's wrong here it can cause banging which will destroy the main vents.

Then, measure the length and diameter of each steam main. Maybe those Hoffman #75 vents are too small.

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Emmett McGuire

Thanks

Thanks for your suggestions.

At the end of the heating season I'm going to look into insulating the mains as a summer project. It seems that can only help. (My Pressuretrol is already set at 0.5# / +1# and water is at 1/3 of the glass - when it is not surging).

I'm going to go with new Gorton #2's - especially since Ken at Gorton told me that there is no such thing as over-venting. It just makes sense to get the air out as quickly as possible.

To preserve the life of my new vents, I'm going to try the simpler approach - an ell to a nipple to an ell - and get the vents off the terminal end of the supply out of the direct path of destruction. (The idea of cracking, rethreading and joining century old iron pipes in order to put a tee in the correct location is more than I can handle right now... )

After that, I'll just have to see how the system operates. I already know that the system has other flaws (e.g. the header was plumbed with copper pipe and the dry returns join before they drop below the boilers water line) but I think I'd better take this one step at a time.

Thanks again,
Emmett

Bob W._3