multiple-boiler design

g squared

thanks to Dan, I think I haver a good understanding of the piping, but I am not sure about the wiring and controls. What have you used on your jobs?

g squared

Dans book "piping away" has convinced me that this is a good idea. But, I need more info on controls. Here is my plan. Two Buderus G124, 103k btu boilers, producing 170k net btu, delivered to 60 year old 2" iron pipe and numerous radiators and convectors, using primary/secondary piping. Are flo cheks recommended? What brand/type of outdoor reset should I use? What boiler controls do you suggest? How should I wire it together? I welcome all replys; thank you for your time and knowledge.

Bob Gagnon plumbing and heating

multiple boilers

I did a couple this way, and it worked out good. Bob Gagnon

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John Starcher_4

Bob, I'm just curious....

....why have the two boilers piped that way? Why not have them both piped into the loop serving the loads?

Starch

hot_rod

I'd suggest

looking at a pair of mod con boilers. Two mod cons give you 10- 1 modulation, A very nice feature for multi zone systems.

hot rod

Rob_37

What software for your piping design do you use?

Bob,

What is the piping software used? Looking to pick up some and also some to draw the loop layouts.

Rob

Bob Gagnon plumbing and heating

electric controls

we used Tekmar, the electrician liked it, he said it was easy to wire. I piped it that way because John Siegenthaler told me to pipe it that way. The boilers are lead- lag, meaning one boiler works for 24, hours then the other boiler works for 24 hours, and if they have a high enough demand, both boilers will work at the same time. I thought not having closely spaced tees on the domestic would allow heat migration, but John said no, and he was absolutely right. The summertime gas bill seems high though, do you think two 80 gal superstors would have much standby loss? The customer said the summertime fuel bills are running about $140 per month. In the winter the fuel prices were reasonable. Bob Gagnon

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Bob Gagnon plumbing and heating

cad software

is HydroniCAD, From hydronicpros.com. Very easy to use and at a reasonable price too. It dosen't do loops though. Bob

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g squared

mod-con

thanks for you input guys. Rod, I was thinking of the mod-con units, then I heard that due to the high water volumn the boilers would not condense for long and therefore would be less effecient. Also, I've heard that these boilers can be sensitive to minerals and dirt which I am sure this system has plenty of. If all thats true this may not be a good application for mod-con. What do you think? thank you.

hot_rod

At some point the dirt

flushes or settles out. Caleffi, SpiroTherm and others have seperators that handle dirt, etc.

I'd still protect the mod cons with y strainers and check them often until the debris settles. A good hydronic fluid would lock up small particles and address the PH etc issues.

Even if the mod cons ocassionally go out of condensing mode, that modulation feature fron 15K to 240K or so with a pair of Buderus GA's would be worth the price of admission in my mind. it's the return temperature that is the critical abspect of condensing and the modulating of the burners happens even at higher temperatures.

I think 26 brands f modcons were counted at the recent ISH-NA show. Must be a reason. These look to be the boiler of the 2000's

hot rod

Ray Landry

If your system is made up of radiators/convectors then chances are it's probably got some oversized radiation therefore you can lower your water temp and condense! Install a Wye strainer on your return with a ball valve for draining purposes. Attatched is a photo of a church I did last year where I did a there boiler system with two gb's on lead lag and a g234 for back up. Each boiler had it's own boiler pump and spring check, air seperator which eliminates the need for primary/secondary and has biult in air elimination and a spot for your expansion tank/fastfill. Good luck! Oh yea control wise I used a Takmar 365(?) my memory is not to good w/ numbers but the contorl was super easy to wire/program

g squared

hey Ray

very impressive job. It sure looks like you earned your money. thats probably the ideal way to go. thank you Ray