What size \"main\" vent do I need?

Jason_44

Just had all my wet-steam problems fixed. You can read all about it here...

http://forums.invision.net/Thread.cfm?CFApp=2&&Message_ID=428253&_#Message428253

I am having one last problem, however.

The two upstairs radiators farthest away from the boiler (two bedrooms) don't always get hot all the way across before the wall thermostat (which is downstairs) is fully satisfied. Therefore, these rooms are cooler than the others.

I have replaced the air vents and shut-offs on these radiators, but still have the problem. The radiators do get hot, just not always all the way across before the burner stops firing. They also don't even start to get warm until the boiler has already been firing for about 10 minutes. The downstairs rads get hot almost right away.

There is a single main-vent in the basement located just before the riser that feeds those radiators. It is a Vent Rite #35 (picture attached).

The vent is new and appears to be working, but it's the only main vent in the system and my theory is that it's venting too slowly, forcing the vent on the upstairs radiators to work too hard, which is not letting enough steam in to heat the radiators quickly enough (that's my theory at least).

Would a bigger main vent help? I read that Gorton makes larger vents. Are there any potential problems with installing a larger vent?

Thanks guys!

Jason

Brad White_203

One Question

Jason, even if the radiator does not heat all the way across, does the room heat adequately in that condition?

If it is not broken, don't fix it.

If you have any issues of under-heating and want to speed it up, a Gorton would work well. To size it, one needs to know the size and length of the main.

If it is just that one radiator (and the others heat just fine), chances are that the appropriate Gorton will work well. You should have dry steam now that Norm worked on it, so maybe a Heat Timer Vari-Valve will work for you- it will outvent any Gorton radiator valve and is adjustable. I would not use them if you have wet steam for they can spit like llamas.

Typically a #2 is pretty versatile and if space is short (literally), a series of Gorton #1 vents (three of these together have a bit more venting than a single #2) and half the height).

Jason_44

The room itself is not getting warm enough (at least it doesn't feel like it).

I can turn up the thermostat and get the radiators to heat all the way across and make the rooms warmer, but that will cause all the other rooms to be too warm.

So, are you recommending replacing the radiator vent with the Heat Timer Vari-Valve and leaving the main vent alone?

Oh, and it was Joel Boucher's guys who fixed the boiler piping (sorry, Norm doesn't get credit for this one).

Jason

Brad White_203

Oh, that's right...

Joel is excellent- I remember now, you were more in Joel's area than Norm's. What does Joel and his group say?

I would do both, replace the main vent with the proper array or single Gorton (details to be worked out), then get a faster vent for that lagging radiator. Short money. (By the way, a single Gorton #1 is worth three VentRite 35's. A Gorton #2 is worth ten of them.)

A Heat Timer Vari-Valve is a good choice for fast and adjustable venting on the tough bugger that causes you grief. Otherwise a Gorton C or D. A "D" equals a #1 by the way, hoo hah!

Anyway, get one in there and let me know what you think. I would do the radiator first because it is simplest and treats the problem radiator, then do the main, just a thought born of nothing in particular.

Steamhead (in transit)

How long is your steam main

and what pipe size is it?

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Jason_44

The main loops around the entire basement and also carries the condensate back to the boiler.

Pipe diameter is 2"ID. 46 feet of main total in the loop. The vent is installed about mid-way through the loop.

JW

Steamhead (in transit)

Are there

any take-offs for radiators past the vent? If so, how much pipe between the boiler and the last takeoff? If not, how far from the boiler to the vent?

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Jason_44

The last takeoff is almost right next to the boiler. Again, the main is a continuous loop with takeoffs (I called them risers before, but whatever) that feed the radiators in various parts of the house. I've been told this is a "counterflow" system.

The vent is midway into the loop, so about 20-ish feet from the boiler. There are 2 takeoffs/risers past the vent.

Steamhead (in transit)

Oh, is this the one

where the main is a loop with steam feeding from both ends, and the vent is on the furthest point in the loop from the boiler?

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Jason_44

Yep.

I'm told this is a very common setup here in New England.

Jason_44

Would you go with the Gorton #1 or #2 for the main vent?

Brad White_203

It depends on the volume and height you have

If a #2 will fit, that is what I would do. If height is short, three or more #1's.

But the reality is, how much pipe at what size are you planning on venting in what amount of time?

If I had to punt, a #2 though.

EDIT: Go with what Steamhead says. If he says use two of these, then make it so...

Steamhead (in transit)

OK

replace the Vent-Rite with two Gorton #2 vents.

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Jason_44

Will give it a shot. Thanks!

Jason

Jason_44

Just an update:

I've got two Gorton #2's on the main and it's working pretty well. Iakes 10-15 minutes for all of the radiators to get hot before the burner shuts off.

I've seen some of you guys gang together a dozen or more of these on some jobs. I feel kinda wimpy with just my two little main vents! LOL

Any reason not to use four Gorton #2's instead of two? I've got a 3/4" tapping.

Jason

scrook_2

Cost of 2 more #2's?

How long's it take for the main to get hot at the vent end and the pair of #2's to close now, assuming a warm boiler start?

No point in counting the time to heat the boiler to start of steaming -- faster vents won't change that.

Steamhead (in transit)

If all the rads

get steam at about the same time, the main is properly vented.

Larger groups of vents are used on larger and longer steam pipes.

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