Venting Capacities application

DuggieFresh5

Hello steam aficionados,

We purchased our first home with steam heat last winter and I have done a lot of reading and learning in the past 10 mos. I started getting massive water hammer after a month or so and had no idea what was going on or what changed. I purchased "The Lost Art of Steam Heating" (Holohan) and read it cover to cover.

After 3 tries, I connected with a tech that new more than me about my system (home warranty restrictions) and cared enough about what he was doing to take the time to teach me some more. I recently purchased "Balancing Steam Systems" (Gill and Pajek) and now I need a little advice on how to apply that information.

I have my Pressuretrol set at .5 w/1 PSI differential. The unit was cleaned during service, so I'm reasonably certain it is working properly. With pressures this low (below 3OZ CFM), Gerry and Steve's charts can't give me any information on CFM for a 3/4" pipe. I've installed a tee on the end of my steam main and want to determine how many air vents to install. A Gorton #2 seems to be the only logical choice based on price to performance.

My tee is 1-1/2" (as is the entire main), and I have room to plumb the vent lines above the main. I have 87 linear feet of main and the home is two stories. Currently, the system only vents on the return side. I think this means nothing was updated from when it was a coal-fired system. I took advantage of the warranty work to clean the original vent and double up on that side.

We had a very cold winter last year and my goal is to get proper venting in place so I can get a good idea of fuel savings this winter. Thanks in advance for your advice!

gerry gill

Is this one pipe steam or two pipe steam? 1 1/2'' main is small. Are you sure about that?

nicholas bonham-carter

Most main vents are on the dry return, so that all the air in the main piping can be allowed to escape. The resistance to the escaping air as steam begins to fill the pipes should be as low as possible, measured as back-pressure 2 ounces.
A good low pressure gauge will show you in the venting phase how much pressure there is in the system, as your boiler begins to make steam.
I recommend at least one gorton 2 for each dry return in a small system, and more for larger. When the gauge shows such a low back-pressure, then your job is done.
Using the balancing charts can be useful for the first step, and then finishing by studying the gauge. In balancing the various separate mains of the system, you are trying to make the main pipes all fill at the same time (and back-pressure) even before the risers to the radiators have begun to fill with steam themselves. In effect you are making all the mains allow air out with almost no resistance.
Websites such as that of the Gorton vent company, are giving wrong advice, even though we all recommend their products! This is not the first manufacturer to offer bad advice in the use of their products!--NBC

DuggieFresh5

gerry gill said:

Is this one pipe steam or two pipe steam? 1 1/2'' main is small. Are you sure about that?

That is the size after the header/Hartford Loop. It is 2-pipe steam. There is a newer piece of pipe with the size printed on it.

Actually, you have seen the system and will install a radiator trap for me soon. The only house in Independence with steam...

DuggieFresh5

Thanks NBC, that's good advice to start with. I will search out a low pressure gauge and get the Gorton's on order. Is permanent installation of the gauge a good idea, or just create a tapping and install for troubleshooting?

gerry gill

Oh yeah, hi Dug..i would rather see the main vents on the vertical drip than straight across that tee..it may work fine, but what i see in my mind is the velocity carrying the water right across the downward opening and into the vents..see what i'm getting at?

DuggieFresh5

I do, and I thought with the vertical space I have to work with, I could mitigate that with an elbow, maybe go up a few inches and branch out with a tee. Put a vent on either side of the tee like antlers. Something to break up the momentum and encourage condensate back down to the main branch tee. Does that sound reasonable?

gerry gill

It does..if i were standing there doing that i would say ''lets try it and find out''...just be aware that if it works with your current boiler, doesn't mean that it would work with a replacement boiler which may make steam faster which would change the velocity parameter.

DuggieFresh5

Thanks Gerry, I'm going to give it some more thought. The drip line placement would be more or less immune to the velocity of steam or water moving down the line. Outside of the "splash zone" as it were.

I've also insulated about 25' of pipe tonight. Looks like I can get another 15' no problem. This is the year of the system tuneup!

DuggieFresh5

This is what I've come up with. Two Gorton # 2's per NBC's recommendation, pitched slightly back. I chickened out on cutting pipe for a vent off of the down pipe, but will try it if this configuration doesn't work out.

Vents on the left are the return side.

Thanks again to everyone for their input!

DuggieFresh5

Update: After some good conversation with Gerry Gill and re-reading his venting capacities guide, I learned I wasn't venting my returns enough. Since I have 2-pipe, the return is at least as important as the main. So, I put up a Gorton #2 in line with the existing Hoffman #75's and maxed my 1/2" tapping.

It may not look pretty, but it should work pretty good. Especially since I also replaced the failed-open trap that was causing my return vents to close and my system to shut down on pressure...

I think I'm still getting better at this!