unyoking a double weil mclain

Joe Grosso

Please go to find a contractor section here and have a pro come out to answer your questions and do a walk through to make sure correctly sized or how to correct the problem that you are having.

john_27

unyokimg a weil mcLain boiler

I have two weil's gas/steam in my basement, which generate a total of 1.8mm btu's and 4700 square feet of steam radiation at 0 psi.
The actual square feet load in the house is 1.3mm including a 20% factor for basement piping- I am literally sized 3-4 times the connected load.The system was installed in the mid 1980's.

I would like to disconnect the relays to one of the boilers, and test the system to see whether the second boiler is needed. Mathematics says it isn't, but...
Two questions....one....will either unyoking or not running the second boiler damage either boiler in any way.....second...if the answer to the first question is yes, can I convert the system to a staged fire...where the second boiler fires up only if needed. I think the installer simply put in the system as if it were a hot water installation, and thought about btu's instead of square feet of radiation... conversations with his son indicated that they are "hot water people". Of course, firing over the connected load simply sends the excess up the chimney, and is ecologicaly wasteful as well as extremely expensive to run. I have slightly downfired the boiler, but this is not the best answer because the exhaust temp needs to be a certain level to prevent waste condensation in the chimney...John

ta finnegan

Testing.

If you are CERTAIN about the connected load, use a pick up factor of 1.3 if the pipes are in good shape and well insulated.

If you unyoke, make sure that the near boiler piping is amended otherwise you are begging for big trouble.

I personally don't like yoked steam boilers you can never get the firing just right, but staging is a possibility with outdoor reset.

I also do not like upfiring or downfiring. The boilers are made to fire a specific way and it messes with their efficiency. With a boiler that large you are already paying a fortune to the utility company.

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john_27

unyoking two weil boilers

thanks for the two posts....but....as an interim testing measure, any thoughts on whether simply firing one boiler will damage the one next to it which is not firing...john

Steamhead

You may wish

to simply valve off each boiler from the system. Use one boiler and keep the other for a backup. In a building that size, this makes sense to me.

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john_27

unyoking a weil double boiler

Dear Steamhead....your post is right on....but...as a test....can I fire one boiler without damaging the one next to it....if the load factor works, which math says it should, I should have plenty of heat to fire the connected load( 1700 square feet of radiation versus a rated capacity of 2300),and have a boiler for backup...so...I would like to do the test if firing one next to an unfired one is ok....I note that each boiler has separate controls....if the test works,than valve off the piping(which looks straightforward because there is only one connection to the load from the boiler I wish to decomission.....john

Dave_4

lead/lag the boilers

at least every other week...alternate them to keep 'em both ready to fire up if the other one goes down

Steamhead

I've never done it that way

so I couldn't give you a real answer. Why not ask Bill Wright at Weil-McLain? He shows up here sometimes.... e-mail him at bwright@weil-mclain.com . He'd know if this would cause a problem with those boilers. Be sure to give him the model numbers.

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Unknown

can you show us how it is piped

near the boiler? I'm just interested....

Noel

ta finnegan

Piping

How the existing piping is and how much you may be willing to re-do will be key to success in the "unyoking"

If you are dead-on with the connected load and your pick-up factors are good, heck, try it.

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john_27

update on unyoking weil boiler

I did the test today. The house heated in a slightly slower time, but did heat nicely. No damage to either boiler. Steam was evident at the end of both main basement piping runs-120 feet from the Weil. I was surprised it took a little longer- I thought steam travelled at a constant rate....but I was firing to 2400 square feet of radiation versus 4700 so....

Noticed one of the blower fans(pushing steam through ducts) needed to be replaced....will do so this week, repeat the test, and then seek more advanced help to test our results. I may not have to repipe, but this will be for a pro to decide. My job is to identify the problem, and test results, so that the final phase solves the problem, and shows respect for the steam guy's time as well.....also, noticed that neither main run has vents(Dan wouldn't like this), and also that one of the two returns( one is on the east side and one on the west)needs work ---minimum flushing, and probably some sectionsmay need to be replaced as well. So...coming along slowly, and still trying to clean up this system...John

ta finnegan

Terrific!

Check your pressuretrol, the higher pressure steam moves slower. Crank it down. Sounds counter-intuitive but it works.

Do the calcs for the pressure drop for your system and try a vaporstat. You will have more variability with lower pressures.

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Steamhead

And

vent those mains! You say the mains are 120 feet long- what diameter is the pipe? I'm sure you need Gorton #2 vents- question is, how many? If we know the pipe diameter and length we can figure out what vents you need and how many.

www.gorton-valves.com

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john_27

unyoking a weil boiler

I have two mains-each 100-120 feet long-neither with venting of any sort-pipes are 6-8 inches in diameter. Sized the motor and called grainger-the dayton should be in stock within a day....several other small switches governing two air handling units(from the twenties) may also need to be replaced. SO...will replace the motor, and figure out why the system isn't vented. Dan, as you know, is adamant about vents at the end of the main runs, and also that the vents are placed 6 inches back from the end of the runs(to prevent water hammer). Also, downloaded the manuals and specs for the two boilers from Weil, and will look through them for fun....although the weil's are from the eighties, the system is from the twenties, and seems still workable...john

john_27

psi

sorry...one of the posts mentioned pressure....system is running at 0 psi...john

john_27

unyoking a weil boiler

got the new 1/3rd horse motor installed so that air flow from the system is restored. I will disconnect one of the boilers tomorrow and observe results.But, I need to vent the two mains...what is a gordon#2 vent......this system isn't vented.

Steamhead

Sizing Vents

you say the mains are 6-8 inches in diameter. That turns out to be quite a difference as an 8-inch main has almost twice the air in it as a 6-incher. We size vents based on how much air is to be vented, so we need to know exactly what size the pipe is. If they start out at one size and end at another we need to know how much of each size pipe is involved. Be sure to measure the pipe itself, not the insulation or the fittings.

The Gorton #2 vent is the largest vent made today. It out-vents the Hoffman #75 4-to-1. If your mains are 6-inch all the way through you'd need 5 Gorton #2 vents on each main and if they are 8-inch you need 8 per main.

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TJ_2

This is a house???

The structure you describe sounds like either an apartment house or a grand old mansion. Can you describe it in more detail?