Main Vents

fxrgrunt

I'm sure this topic is beat to death on the daily but here we go. I have two main vents on 2"mains. The left main in the picture is 66ft long and the right main is 47ft long. The 66ft has a Hoffman 4a currently and the 47ft a Hoffman 75. I thought that was odd being I figured it would have made more sense if they were swapped. I do they they are working alright but in the name of efficiency I would like to make my system operate the best it can. So what would you guys recommend I run in this setup?

nicholas bonham-carter

Where are the bottoms of those pipes connected?
Add at least one Gorton #2 to each, and maybe 2 will be needed to allow the air to escape with minimum resistance, (2 ounces backpressure).—NBC

fxrgrunt

nicholas bonham-carter said:

Where are the bottoms of those pipes connected? Add at least one Gorton #2 to each, and maybe 2 will be needed to allow the air to escape with minimum resistance, (2 ounces backpressure).—NBC

They connect together into the wet return.

fxrgrunt

So would gorton #2 always be the consensus vote? Not adding another or multiple Hoffman 75 or multiple Gorton 1s? 

ethicalpaul

Well I like to not overbuy on vents so I’d try out a MoM #1 which is the same rate as a Gorton #1

JUGHNE

It looks like the small nipple coming up it only 3/8" but it may suffice for 2 G2 vents....someone correct me if wrong.

I would though, add a 90 and then a long nipple then a 90 and go up high as possible for vents. Your long nipple should be parallel to the steam main so you get slope for drainage back into the main. You could use the bull of a tee at the top and come out each side for 2 vents.

Having those 90's and riser may keep a water slug from hitting your vents.

fxrgrunt

JUGHNE said:

It looks like the small nipple coming up it only 3/8" but it may suffice for 2 G2 vents....someone correct me if wrong. I would though, add a 90 and then a long nipple then a 90 and go up high as possible for vents. Your long nipple should be parallel to the steam main so you get slope for drainage back into the main. You could use the bull of a tee at the top and come out each side for 2 vents. Having those 90's and riser may keep a water slug from hitting your vents.

The top of the T on each side looks to be 1" bushed down to 1/2" then up to the used the 3/4" to 1/2" reducer to attach the main vents. In my head I was thinking to remove the reducers, add a 1/2" y strainer  to protect the vents and add some height on each then a 90, long nipple, then two MOM #1 on the 47ft line and three MOM#1 on the 66ft line. Let me know if that doesnt make sense. I hear the Gortons are great when working but also fail. I figured having multiple vents on each provides some redundancy and the MOMs arent bad priced.

dabrakeman

Venting rates at 2oz:
Hoffman 75 - 0.75ccm
Hoffman 4A - 0.216
MOM#1 - 0.59
Gorton #2 - 1.75

So, you see the Gorton #2 offers a lot more venting than the others. If you are cheap like me you could build an antler on your 47ft main and put your two existing vents on it. Then plop a Gorton #2 on the 60ft. If you want to maximize your venting then build an antler on both and put the two existing vents and a new Gorton on the 47ft and two Gorton #2's on the 60ft main.

dabrakeman

No doubt the MOM is a low cost vent but I don't have any experience with them.

fxrgrunt

dabrakeman said:

No doubt the MOM is a low cost vent but I don't have any experience with them.

I just have to get the bushing off going into the 1" T. That way I can change the nipple from what looks to be 1/4" to a 3/4" into an antler.

dabrakeman

Just curious whether you have stood down there during a cycle to see if indeed your 75 is closing sooner than the 4A. If can't hear them you can just feel the ends of the mains to know when the steam gets there. The location of yours makes it easier than having to run back and forth across the basement like myself and probably many others. Less exercise though:) Of course you or someone before you might have balanced the existing setup more by venting the radiators faster off the long main. If you get closer to a 60/47 ratio in your main venting rates you may also need to rebalance the radiator vent rates a bit.

dabrakeman

I believe a 1/8" pipe at 2oz vents at ~2.0 cfm and a 1/2" pipe at ~3.4 cfm so would imagine a 3/8" would be somewhere in between, maybe around 2.7cfm (anyone else have some numbers on this?). If so then if you don't want to go more than that on your total venting per main then theoretically the bushing should not make a difference. If you wanted two Gorton #2's then it probably could have some effect. Maybe you give an honest effort to get the bushings off and if they don't cooperate then just leave them and build the antlers off the existing bushing and just don'[t maximize your venting for the rest of this heating season. Tackle them and expand your venting further in the Spring. Of course where I am right now we are about 30+ degrees above normal so it is like Spring for a few days!