VAPOR

cliff dennis

scenario:agreed to install boiler as sub as competitor was not skilled in steam.old boiler was nasty and gas convert 30 yrs old.did job, new header,boiler was provided.System is old 2 pipe vapor system.Trane convectors,orifices on inlet fitting.installed vaporstat, started at 8 oz.most of main in crawl is uninsulated. in process of remedy.two supply mains and return mains return to boiler room and drop int return header.no traps, no air eliminators no signs of such.house and system 1933.#75 vents on all 4 end of main and dry returns.system heats too slow and too long to get to 2nd floor.raised vaporstat to 12 some improvement.2 rads added on addition had no traps, we added to avoid equalisation, and now one of them wont work.any input helpful.

Steamhead

Trane Vapor system

Do the original convectors have traps, or just the supply orifices?

Measure the length and diameter of each steam main to see what size the vents should be. For the dry return vents, you can use the old #75 units.

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cliff dennis

vapor

no traps.supply main is 20 ft 2 in. then tees off and 1&1/2 runs bak to boiler approx 40 ft, each has a 75 vent at end in boiler rm.returns start at the tee and run back to boiler rm dry, 75 vents on each. thanks

Steamhead

That's an Orifice Vapor system

Vent the end of each steam main with a Gorton #2. The dry returns can use the Hoffmans.

To straighten out the addition radiators will require some investigation. Traps aren't the answer here. You need to determine what boiler pressure will fill the existing convectors to 80% of their capacity. Then take that pressure to an orifice sizing table and determine the orifice sizes that will do the same thing on the addition convectors. Get some disc orifices in the proper size, or get blank ones and drill them yourself, install them in unions on the addition convector supplies, and all should be well.

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cliff dennis

vapor

that orifice idea is new. I didnt think we could do that but Ill try it. I am not familiar with gortons but will look for them.By the way the main heats all the way to the end pretty quick, its just a couple of rads on the second floor nearest the end of the main, risers are hot but they are taking to long to heat. Today i replaced the old sears stat(4 ded over)with new honeywell vision and set cycle rate to 1, finished insulating the main in crawl,40 ft, and reduced the firing rate. yesterdays rad load i did came out to 580 ft...boiler is 760 ft. by the way I am convinced somewhere in the last 40 years, someone removed all the gadgets that used to separate the supply from the return ie air eliminators, traps, check valves and such, what are your thoughts?

Steamhead

I've done it

that's how I know it works! We added to a Trane Orifice Vapor system by using Slant/Fin steam baseboard, and put unions with orifices in them on each baseboard supply line.

The Orifice Vapor system is the simplest of all heating systems since it was designed to minimize the number of moving parts. It depends on accurate pressure regulation at the boiler to keep steam out of the dry returns. Before the mid-1920s or so this accurate regulation was not available, which is why earlier systems had traps or other return-line devices.

The orifices are sized to only allow the convectors to fill to 80% of their capacity at a given pressure. This way, all the steam condenses before it reaches the return connection. BTW, this 80% rule will also affect your boiler sizing!

Trane had a pretty powerful presence in the Baltimore area, so I've gotten to work on several variants of their Vapor systems. They were all piped pretty much alike, but the earlier ones used cast-iron radiators and traps where the later ones used recessed fin-tube convectors. The earlier convector versions also used traps, but the later ones had orifices cast into the convector elements. So I'm sure your system never had any traps.

All the Trane systems I've seen used standard main vents rather than float trap/air eliminators. The main-vent upgrade I suggested will get the steam to those slow risers much more quickly, which should get heat into the convectors faster.

Gorton's site is www.gorton-valves.com . Get in touch with them if you can't find their vents in your area. Talk to Ken Kunz and tell him I sent you.

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Ernie

? Steamhead

Any way to tell if Trane recessed fin-tube convectors have orifices cast into convector element?

Steamhead

If it's a Vapor system with no traps

they almost certainly do.

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Ernie

cast orifice convector elements

Is it possible to have traps and cast orifice in convector elements with a Trane Vapor System,if so what would the effect be?

Steamhead

It's possible

and should work OK. Many Vapor systems such as the Hoffman, Dunham or Webster systems used both orificing shutoff valves and traps on the radiators.

If those convectors do have cast-in orifices, you won't be able to get at them. To check, reduce the pressure at the boiler to 6 ounces or so, and if the system is properly vented and the convectors only fill part way, they're orificed.

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cliff dennis

VAPOR

THANKS MUCH! That was great info. I have been away from a few days.I guess that explains why the customer is getting a flushing noise from the two copper fins I put the traps on. I will remove them and do the orifice thing.I am going to check with factory re; downsizing the boiler 20%