Number of main vents

Neild5

I live in a 20 unit condo building built in 1927. Single pipe steam, original unit was coal, updated at least 3-4 times, last one was 5 years ago with a 1.5 million BTU boiler. Three years ago right after I bought my unit the controller was replaced with a Trs wireless control with 4 sensors. The unit furthest from the boiler is always 8-10 degrees colder than the rest until outside temps drop under 20 degrees then it is 1-2 degrees less. Luckily the contractor the management co uses is not a knucklehead, he admits his limit is cleaning the burners and replacing the igniters. The long main is 85 feet of 6 inch pipe then an additional 35 feet of 4 inch. Where it steps down from the 6 to 4 inch there was 1 Dole #1C vent and a Maid o Mist #1 at the end of the 4 inch. From all the reading I have done I know it is not enough but how much should there be? The short main is 25 feet of 2 inch pipe with a small vent, I can not see the size but the 3 units it feeds are all toasty.
Thanks in advance.
Neil

BobC

For optimal results use 1 Gorton #2 for each 20 ft of 2 " main.
A ft of 6" main contains 9X the air a ft of 2" main
A ft of 4" main contains 4X the air a ft of 2" main

The venting has to be balanced between mains, by their volume, for good steam distribution.

For optimal venting 20 ft of 2" main needs 1 Gorton #2
For optimal venting 5 ft of 4" main needs 1 Gorton #2
For optimal venting 2.2 ft of 6" main needs 1 Gorton #2

You can get by with less venting but fuel usage can be higher because the builer has to fire longer for steam to get down the mains. Note a 3/4" outlet can only handle the venting needs of 4 (corrected thanks to @EzzyT ) Gorton #2's. Multiple outlets will be required on some mains to handle the number of vents

Your mains are massively undervented as they are now.

Bob

EzzyT

@BobC Its 4-Gorton #2's on a 3/4" outlet.

nicholas bonham-carter

Maybe this is a situation for the use of steam traps as vents.
The opening and closing temperatures would be better suited to complete venting.
Someone here is making some tests using traps as vents, but I have not heard the outcome.--NBC

BobC

Asco makes a line of steam rated solenoid valves.

http://www.ascovalve.com/Applications/News/News8220Steam_HotWaterValve.aspx

Seems like a good candidate for an option (with a good control scheme) vs a large number of air vents.

Bob

Neild5

Wow 45 #2 vents! I doubt the board will approve that expense.
Thanks for the info. The Asco valve sounds interesting.

BobC

45 #2's would be optimum but you could start with 1/3 that number and see how it does. They don't exactly give the asco steam rated valves away either.

Bob

KC_Jones

Neild5 said:

Wow 45 #2 vents! I doubt the board will approve that expense.

Thanks for the info. The Asco valve sounds interesting.

They are spending that money now in wasted fuel. They have already approved it and don't realize it. Personally I would rather spend it once than every year for the rest of my life.

SWEI

Given the size, some alternative options might be worth exploring. Big traps (we've seen Nicholson and Monash models applied here) would be the simplest option. I'd really be tempted to try the solenoid valves along with a small DDC controller. This will produce some interesting data that can be used to optimize the system.

BobC

@SWEI i found the price of those steam rated ASCO 8200 series solenoids very high, other manufacturers may be more reasonable. I do agree the possibilities are interesting.

Bob