Mammoth one pipe system

DanHolohan

with some big Gorton D vents on this one.

Mike Sullivan

Mammoth one pipe system

10-30-04

I am working on my church's boiler system. The 1922 building was designed with an 8200sqft Steam boiler (78hp ?). The drawings I have show that it was a closed system (no return tank or pump). Since at around 1961 the 42hp replacement system has had F&T traps and vent at the end of the main. A 115 gal return tank handled both returns. Only 42 radiators remain of which 13 are turned off. 10 or more have been removed in the past.

The one pipe system leaves the boiler room at 6" dia for 30 ft. (1-90) then tees to 5" and 4". There is 176 ft of 5" (4-90's) finishing with 40ft of 4" back at the boiler room. The 4" branch has 45ft of 4" (1-90) finishing with 18ft of 3" (1-90) back at the boiler room.

The 1961 1/2 pound system had 1 #75 Hoffman on the 4" return and a 1 1/4 F&T trap. The 3" return had only the 1 1/4 F&T trap. The 29 active radiators mostly had .040 vents, even on the 3rd level.

My new boiler is a 24hp Burnham V906 with a PowerFlame burner. Planing on 1/2 pound pressure. I am sure that the system was not right for at least the last 43 years, as it is not right now, in that getting any pressure is difficult.

I installed a new #75 in both returns (10" risers) and rebuilt the F&T traps. All new Maid-o-mist radiator vents with changeable vents. I sized the vents according to what I have read, all in all much larger than .040s.

First cold start up took an hour to get heat at the long main trap and I had water spitting out the #75 vent. I took the F&T trap apart and checked the hole size in the float check to make sure it was the same as what I took off, Same 0.390. I noticed the valve part of the kit had a 0.060 larger ball, so I bored out the seat to 0.454. I also installed a second #75 vent beside the other one. Again a cold start, heat at trap after 1 hour, but no spitting at the # 75s.

During the hour of waiting for steam to reach the end of the main the water level is not stable in the boiler and when checking the radiators I noticed the vents were pulsing.

I feel that I have at least 2 problems. First the boiler makes steam quickly and when the steam reaches the cold piping it returns to water creating a vacuum within the pipe behind the moving exiting cold air, but in front of the oncoming steam. Thus the steam rushes harder (in the vacuum) and begins to become wet and the boiler water surges. This becomes a vicious cycle requiring more water and before long the mains are flooded. The second problem is that I can't get rid of the air as quick as needed. I have done the math on this mammoth system and found that I have about 465 cubic feet in just the mains not counting the risers to the 2300 sq. ft. of radiators.(radiator volume unknown)

I have installed a vacuum breaker (just a 3/4 swing check valve) on the steam pipe above the boiler to try to stop the surging. (I have not tried this yet as I won't have the #75s till Monday) I have also thought about restricting the inlet to the 6" leaving the boiler room to slow the steam down.

I am also installing 2 more #75s, though I feel that this like 2 more nails in a car tire, what I need is a blowout.

What can I do to get rid of the massive volume of air in the system to speed up the 1 hour interval on cold starts. I have not been able to do a prolonged test, as it has not been cold enough.

I await your comments.

Mike Sullivan
PO box 213
Fairfield, IL 62837

Ph 618-847-4132
Fax 618-842-5068

Mark W

And...

how is the insulation on the mains?

Unknown

Also , check to make sure

the near boiler piping is correct . Very critical to keeping the boiler water line steady and the steam relatively dry . Since it's a new install , has the boiler been skimmed and the returns flushed out ? Would you have some pics of the boiler you could post here ?

Heres a V905 we installed last year , sorry about the lighting . Same symptoms you described , except for the spitting vents . The homeowner insulated all the mains and the problems disappeared .

Boilerpro_3

Mike

Bigger main vents should help. The Gorton number 2 has a 1/2 inch orifice and since you're near Chicago, Engler Distribution should have them. The 75's are about 1/4 that size. I'm over in Amboy, IL southwest of you. Pipe insulation is needed. I wouldn't get the rad vents too big, because they will end up venting the main too quickly, so steam won't get out to the end fast enough. Your surging problem is probably related. If you are making wet steam, it takes forever to fill the main. Talk to anyone who had an WM MGB steamer and they can tell you.
An observation from a fellow steam nut and customer in Chicago (Don) found that as soon as his system needs more pressure before the steam main fills, he knows the boiler is getting dirty.
Oh, and he heats his complete one pipe steam system on 2 to 4 ounces of pressure, so it doesn't take much. And with your oversized mains, you may need even less pressure.


Boilerpro

gerry gill

try this approach,

take off the air vent on the long main and install a full port ball valve..leave it open for a test run..fire the boiler up..time how long it takes to get steam to the end of the main..that will be the best you will do short of vacuum assist..now add as many air valves as it takes to get the same ''time'' between steam up and steam to the mains end..

don_52

your too kind...


the manangement response; ( per tl nancy )

"steam nut", perhaps. "completly nutz", most assuredly!

i've got to write up the blow by blow of that install
the before and after and excellent results.

hats off to boilerpro on a "classic"

thats 2 ounces at design load.

regards, nutz

Steamhead

To find out

how many Gorton #2 vents you need on each main, measure the length and diameter of each main and post it here. We'll tell you what you need. Those Hoffmans are woefully inadequate for anything more than about 25 feet of 2-inch pipe.

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Mike Sullivan

Mammoth one pipe system #2

I stated in my post the pipe info Steamhead ask for, though I made a mistake in the volume math. Total volume is about 39 cubic feet. 25 feet of 2 inch would be .545 cubic feet. 39 /.545 = 71 #75 Hoffmans. Just how much bigger is a Gorton #2?

I do like Gerry Gill's idea of having a ball valve wide open and checking the time for steam. I'll do this in the morning.

Boilerpro_3

One addition

If the rad vents are real big (as in too big), I would suspect the steam will be heading to the closest rads before the mains vent completely, greatly slowing down the warm up time and throwing off balance.

I see it as a need for two things working well together, Vent the mains quickly and fully AND vent the rads slowly to direct the steam down the main on start up. Then vent the rads proportionally to the heating load in that space and account for the volume of air in the rad...ie A 35 EDR flue rad will need alot larger vent than a 35 EDR small tube rad to heat up completely over an hours time.

I have been looking at Steamheads venting tables and seeing how difficult it is to get vents small enough to vent the rads slow enough to provide good system balance without having a greatly oversized boiler.

Boilerpro

Boilerpro_3

Gorton #2 is about 4 times the size of #75....NM

Boilerpro_3

Day by Day I'm starting to feel like the \"Classic\"

Say Hi for me to the management and the fearless attack dog! Glad thngs are working out, with a little help from you.

Dave

Steamhead

Missed it the first time

but here is what you need: Seven Gorton #2 vents on the long main and two Gorton #2 vents on the short one. These can be installed in a "tree" of piping at or near the end of each main. With this configuration there is no need to install any vents at the end of the 6" section.

When the vents are installed, the mains will fill with steam in about a minute or so, measured from the point at which the boiler starts producing steam.

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Mike Sullivan

Mammoth one pipe system

Seven #2 on the long main, now that's a lot of vents. Has anyone tried using a capilary action type valve as vent? This would have a large volume ability.

gerry gill

well, you could use

a radiator trap or a similar steam trap..many of the early systems that i've uncovered paperwork on used these as vents..they didn't call them radiator traps tho..they were called thermostatically operated valves..but they were just your every day 'ol steam trap/radiator trap/blast trap..