Two Handful of Steam Problems on one jod

Steamhead

If the boiler has been replaced, the dry return vent tee may have been removed. In that case we can drill & tap a 3/8" or 1/2" hole in the return to install a vent.

If you have to vent a 1-1/2-inch main that runs 125 feet, you need to use a Gorton #2 vent. Use the same vent on the dry return. If you can't find Gortons in your area go to www.gorton-valves.com to see who carries them. If no one does in your area they will sell to you direct.

Orifice Vapor systems are wonderfully simple. They have the fewest moving parts of any system out there. All you have to do is keep the pressure low, and they heat quickly and quietly.


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Randy Berg_2

I have been in this trade for over twenty years and learn something new all the time. I was asked to look at a close freinds heating system in his house. I have worked in the commerical field, and not in the residential field. Any and all input will be helpful. Some times you can't see the forrest for the trees. This is a two pipe sytem cira 1947, with a lineral main piping of 125' in the basement. It has main vents on both mains, seven convectors with air vents installed. System does not have any steam traps. Boiler was replaced in 1997 with a W/M SGO 3, and insulation was removed on all supply piping and header in the basement. I contacted W/M and got their specs on this boiler.
Waterside, Found boiler water dirty and foaming was taking place. Skimmed boiler, and cleaned with TPS. Also replaced all the vents with Gorton's.
Nearpipe boiler piping, it is within W/M specs, but the riser has been downszed from 21/2 to 2" to the header, but as I stated this is within their specs. Could this be drawing the steam out of the boiler too fast? Velocity would be greater?
Oil side, found fireside dirty, cleaned and replaced oil nozzle with correct Delvan .85 70 B nozzle. Found drafting issues, not correct draft, corrected problem. As per W/M oil pressure should be at 140 psig, due to the short cycling of the burner set pump pressure to 100 psig. Here is a question that I asked and never got a straight anwser. On the boiler nameplate it states max. firing is .95. At a pressure of 140 psig a .85 nozzle is increased to 1.01 gph. Found pressuretrol set at 3.5 psig, turned the pressure down to 1 1/2 psig operating pressure. He does not have the money right now for the piping insulation, so we insulated the header and mains with rolled house insulation, until this spring or summer when he has the money. The convector's nametags have about twenty coats of paint over them. I feel that the boiler is oversized, but until I can find the Sq. Ft. staem ratings of the convectors I'm not sure. It is still short cycling but not as bad as before. There is even heat thru out the house now. One a cold start up the burner runs for around ten mins. then the short cycling begins, off for about a min, then back on this will happen around five times before the stat cuts the system off on temp in the house. Am I'm missing something, or am I'm on the correct path?

Steamhead

Doing fine so far

bet that cleaning made a big difference!

If the boiler's nameplate specifies a max firing rate of .95 GPH, then the .85 at 140 PSI is too big. Try a .75, which should give you about .90 GPH at 140 PSI. Overfiring can cause surging on its own- even with clean water.

The lack of insulation is certainly wasting steam. That said, I'll bet the boiler is shutting off on pressure before the thermostat is satisfied.

You say the main is 125-feet long. Is this the length of just the steam main, or the return as well? What diameter is the steam main? If we know its length and diameter, we can calculate how much air is in that steam main and make sure it has the proper vent. If the main vent is too small, it can cause short-cycling.

Get Dan's book "E.D.R." to determine the convectors' capacity. You can order it on the Books and More page of this site. If you have something really odd and it isn't in the book, post some pics here and we'll do our best to identify it.

Which brings me to something else: A two-pipe steam system with convectors that don't have traps? There's a chance that could be an Orifice Vapor system that has been butchered. Here's a pic of a convector in one such system I ran into. The cover is off, but it has a damper with a knob on the front that I believe has "Trane" on it. Trane made this particular system. The orifices were originally cast into the convector fin-tube headers.

On your system, look to see if there is a tee at the end of the dry (above the waterline) return that has a plug in it. If so, this was where the return vent was. It eliminated the need for a vent on each convector. Also, find the smallest convector in the house, remove the element and try to blow into the supply connection. If you feel some resistance, there's probably an orifice in there.

Orifice Vapor relied on accurate pressure regulation to keep the steam from reaching the dry return. Most such systems maxed out at 8 ounces or so. On a modern boiler you need a Vaporstat to keep the pressure that low. A standard Pressuretrol won't do. There should not be any steam in the dry return on a Vapor system.

It pays to look over every inch of a steam system. That way you know what you're looking at!


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[Deleted User]

I will

assume that the burner is not being cut on and off by the pressuretrol or the low water cutoff. That leaves one other possibility.

The cad cell relay that comes on the burner is rated for .2 amp heat anticipation at the stat. Sometimes on steam, that .2 setting can cause just what you describe. Try increasing the anticipator setting to .4, or higher, and see what happens. Just might cure your problem.

As to the .85 @140, I asked a Weil Rep about that. Got a verbal shrug of his shoulders. Confidence in their oil specs is not high.

Good luck.

Randy Berg_2

For Steamhead

There is no tee as you stated on the return. But the pic that you posted looks like what he has, and he removed the paint from a nametag and they are Trane convectors. The main piping size is 1 1/2" at 125 total feet not including the returns. I will remove the smallest one and check to see if there is an orifice. I do think this is a system that you stated.