main vents

Flip

Have 40ft of 2-1/2" , 75ft of 2" supply main and 15ft of 3/4", 25ft of 1",75ft 1-1/4" return on my two pipe vapor system running the perimeter of the basement feeding rads on the first and second floor. looking for help on vent sizes for the end of each line.

Dave in QCA

more information

What type of two pipe system is it? Trane, Hoffman, Dunham, etc? Some two pipe systems used main vents and others used crossover traps. If yours was set up with crossover traps, they work great. Usually no need for additional venting. Systems that used main vents may need more venting than what the original provided and in many cases, original vents have been replaced with types that do not have enough capacity.

Flip

vents

Thanks for the come back Dave, It is a Trane system, I believe the exsisting vents to be original. The dry return says Trane #2 Quick vent. The wet return says Trane Float Vent. There is a number cast in the side of it of 1010-1.

Dave in QCA

Good Reliable Vents

Those old Trane vents are very reliable and are probably working just fine. The Quick vent should be on the end of the steam main. Because of the pressure, condensate should never be at this location and so a float is not necessary. On the condensate return piping, it runs at atmospheric pressure and so in cases where the boiler pressure rises, it is possible for condensate to stack up in the condensate piping, thus the need for the float. However, you probably also have a Trane Return Trap, and this device uses a little steam pressure to push the condensate back into the boiler when the pressure might be too high for it to flow in by gravity.



Others on this forum might disagree with me, but I think your main vents should be completely adequate. They both vent at a rate of 0.780 cfm at 1 oz of pressure. That is not as much as a Gorton #2, but then they won't have the problem of being partially closed at temperatures above 130F. I discovered that in my system, with one cycle per hour, the well insulated steam mains were warm enough that the air being vented was warm enough to cause the Gorton #2 to be partially closed, and thus I was not getting the performance from them that they are supposed to be able to deliver. The good thing about the Trane Vents as well as Hoffman vents, they say 100% open until they are 190F or thereabouts. If your Trane vents are making any sizziling sounds after they have closed from the presence of steam, you should be able to clean them by flushing some vinegar, Lime Away, or CLR through them. Let them soak a little while, then flush with water several times.



if your radiator traps are all working correctly, the vent on your return piping will never see any steam anyway. If the boiler is being kept at a good low pressure and/or your return trap is working correctly, it will never see any condensate either. It is pretty much just a safety device except the for the little wafer that may still be in the relief port. It is there as a vacuum check. It lets the air out, but not back in. Many times these are removed when the system is converted to gas. However, many of us find it useful to allow the system to go into vacuum when the boiler shuts off as the steam may circulate a tiny bit longer, and on the next startup, there will be hardly any air to expel at all and the circulation of steam is easier to establish and the circulation will be more even.



Are you getting even steam distribution? Does steam arrive at all of the radiators at about the same time?



Here is a link to a Trane publication located in the Heating Help Library.

http://www.heatinghelp.com/files/articles/1392/26.pdf

Flip

vents

Ok will leave them in for now. I do see a lot of respect for the Gorton vents on this site. I happen to be just down the road from you and have not found a local supplier that carries Gortons. In the process of changing out the boiler just skimmed it today, and want to make sure all is ready for cold weather  TY

Also can the Hoffman 75s be cleaned, have one that wouldn't shut down last year

Dave in QCA

Hoffman main vents

Yes, Hoffman main vents can be cleaned. I have used limeaway on them with great results. I have heard that others use vinegar with good results too. My experience is that a Hoffman 75 usually needs to be cleaned every 2 or 3 years.



Yes, Gortons are quite popular. When they are less than 130F, they vent fantastic. When compared to a Hoffman they vent twice as much and cost half as much. But, depending on the system and the building, they may work the way they're rated on a cold start-up, but on hourly cycling, if your pipes are well insulated in in a basement that is not very cold, you may find that they just don't work they way they are supposed to. Anyway, that was the way it worked out for me.



How far away are you? If you want to try some Gorton #2 vents, I have 4 of them that were used 3 seasons. I'd let them go for the price of one.

Flip

vents

The steam main is well insulated, so I will try the existing vents as the season starts. As for the Hoffman I will try and clean it, it is actually on a different but identical system. When you did the lime away did you just fill the vent and let it sit for awhile ? I work in the QCA so if those vents are available I may try and get with you later on. Thanks for the offer.

Dave in QCA

Hoffman main vent cleaning

I simply removed the vent, poured some limeaway in through the pipe fitting opening. Plugged with with my thumb and shook it around. I let it set for about 3-5 minutes, shook it some more and then dumped it out. I repeated the process, then rinsed several times with clear water.



I have cleaned many this way. One, at a friends business was not closing at all. Some with minor sealing issues will hiss and leak a very small amount of steam. One that I cleaned up successfully was passing large amounts of steam.