Twin Boilers - One Pipe Steam System

JStar

DAY ONE:



Out with the old, in with the new. We'll be staging on temperature and pressure. The original 5" header was kept in tact, and only modified for the new drop-in boiler risers. The old boiler water line was about 12" taller than the new boilers, leaving all of the wet returns exposed to steam, so we had to choose between stacking the boilers on top of 5 cinder blocks, or creating a false water line...we chose the false water line.



You'll notice the Knucklehead Inc. piping job on the boiler. They went from 4" at the boiler, down to 2-1/2", then back to 5" at the header. STEAM SYPHON!



Here are some photos of the first day.

JStar

NEW

Pictures of the new system going in.

BobC

DRY!

That steam will be drier than one of Hawkeye's martini's.



Bob

JStar

Dry steam

54" from the water line to the top of the drop....why not, right?

Dave in QCA

Interesting!

Do I understand that you're going to stage this one-pipe on temperature, as in a 2 stage thermostat? If so, I'll be interested to know what radiator vents you use and whether you are able to get even steam distribution. Obviously, this will disregard the pickup factor issue.

Unknown

love the drop header!

Love the drop header! What brand boilers are these??

JStar

Staging

I am incredibly skeptical and half-worried about the effectiveness of the two-stage thermostat in a one pipe system. My gut feeling is that we'll scrap the t-stat staging and stick with pressure staging. I figure it's the same t-stat we would use anyway, so no loss on parts. The mains are well insulated and we'll be upgrading the main venting with a healthy dose of Gorton 2's. I'll keep this thread updated as the system rolls on.

JStar

Boilers

Smith series 8, sans jackets.

Dave in QCA

What I was thinking

Even distribution will be the challenge. However, as per Dave Bunnell's writings on the subject, he advises that if fast main vents are used and very slow radiator vents, say no faster than a Hoffman 40, that even distribution can be achieved from boilers smaller than standard formulas would dictate.



I will be very interested to hear how it works out.

JStar

Venting

We're going to try to vent the entire first floor with Gorton 4's and the second floor with C's or D's. In my mind, disttribution is only a problem in having to deal with the extra piping for the second floor. If we throttle the first floor, the steam should favor the second floor enough to be even. In other words...we're going to try it and see! Luckily, this job is about 20 minutes from my house, so I won't mind making a few trips to get it right this winter.

jumper

outside temperature

Why not stage according to outside temperature? One pipe works best when it doesn't cycle too often.

JStar

Steam

All steam works best with long, gradual cycles. The whole point of the pressure staging is to let the system simmer and not bang on and off every 15 minutes. Outdoor reset for steam is just too expensive right now (until MarkS finalizes his conrol package).

Eastman

what systems

are available?

JStar

FINAL

Too many late nights to update this thread every day. Here's the final product.

JStar

PHOTOS

A shot of the TACO 2 stage relay and main vents. We also added a missing vent to a branch-off of the main that handled a few radiators over a crawl space.

Bio

Very very nice

job you guys did, they will last for a very long time, home owner must be happy

Dave in QCA

Thank You

Joe, what a fantastic install! Truly a thing of beauty. And, thank you so much for taking all of the extra time to take pictures and post the job on HH.

JStar

Steam

Thanks for the compliments. What's the point of doing a nice job if ONLY ONE PERSON gets to enjoy it?!?! The pictures are our guilty-as-charged trophies.



PS. We'll be doing another twin system next week. Teaser: 6" drop header.



I'll try to keep this thread updated this season. We'll see what kind of venting and controls end up working the best.

vaporvac

Keep 'em comin'!

OMGosh!!! That is crazy amazing. I'm totally into these posts. (I wonder why given my upcoming twin install?) Thank you for the detailed pics, especially the controls which often get glossed over in favor of the headers.

nicholas bonham-carter

2 boilers or 1?

What drove the choice of using 2 smaller boilers instead of one larger one? Was it the availability off the shelf of preassembled boilers as opposed to boxes of parts which need to be assembled on site?

I think the staging on pressure control will work best, and maybe the vapor stats could be mounted on the header--NBC

JStar

2 vs 1

System efficiency.



With a staged system, most of the winter, only 1 boiler will need to operate, cutting the fuel bills down dramatically. If 2 boilers need to fire, the second one will shut down on pressure once the mains are full of steam. Plus, there is a level of redundancy to keep the heat going if one boiler ever goes down.



The Vaporstats are essentially on the header. They are installed on a tee of one of the boiler risers, close to the header. Same pressure there as is in the actual header.