General boiler installation questions...

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Old 08-30-08, 08:51 PM
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General boiler installation questions...

I'm going to put all my boiler installation questions in this thread from now on, and those interested in answering can do so. Thanks.

My old boiler had two pipes for the return and two for the supply, all 1 1/4 inch. Is it an issue to connect these together, moving into 3/4 inch piping to connect the old system to the new boiler?
 
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Old 08-30-08, 10:20 PM
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No... you can't do that (if I understand what you are asking)...

Do you mean that you want to try to push the flow from TWO 1-1/4 pipes through a single 3/4" pipe ?

Think about the volume of water... let's pretend it's traffic on the beltway... you are trying to put two four lane interstates on one secondary road ... can you say bottleneck ?
 
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Old 08-31-08, 09:16 AM
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That's about what I figured, it sounded unworkable. Just hoping it was super easy, ha. So, solution? How would I get the flow from a single 3/4" to two 1 1/4" and the flow from two 1 1/4" to a single 3/4"? Can that be done gradually? Or is it even feasible? Would I instead need to replace the 1 1/4"?
 
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Old 08-31-08, 01:14 PM
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Your new boiler is going to probably have at least 1-1/4" supply and return, isn't it ?

I don't even remember what boiler you have, and the particulars about the job ... some pictures would help a lot ...
you can set up a free account at www.photobucket.com and upload them there. Give us a link to view the pics.

A general rule is that 2 pipes of the next smaller size can be joined and fed with the next size up ... example, two 3/4 can go to 1" ... two 1-1/4 can go to 1-1/2 almost ...

Chances are that you can join the two 1-1/4 with tees, and go right into 1-1/4 ... but to be sure we'd have to see the pics and know more about what kind of system you now have.
 
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Old 08-31-08, 03:11 PM
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Alright... I have no digital camera though... will get a hold of one sometime. the supply and return on the boiler is only 3/4 inch, otherwise I'd just use 1/4 for the whole thing. I think that the old boiler just used the heat of the water to circulate, thus the bigger pipes. It seems like 3/4 would be enough for the house though, as I don't have any runs that are too long and it's only 1172 sq. ft.

EDIT: The boiler is a vitodens 100. The job is "simply," but not exclusively, attaching the old pipes that run to cast iron radiators to a new boiler.
 
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Old 08-31-08, 05:12 PM
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Vito 100? Nice boiler. Read, understand, and follow the directions.
 
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Old 08-31-08, 05:17 PM
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Sorry, I know next to nothing about them ... wall hung, condensing ... etc, too fancy for me...

I can tell ya this though... pay strict attention to the manual !

I hope yer pulling permits and will have everything inspected.

You do know that you'll have to run a condensate drain and use an acceptable neutralizer for the condensate before discharging to drain, yes ?

There are a few guyz here who can advise ya better than I can on that one...
 
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Old 08-31-08, 06:16 PM
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Use a Low Loss Header. It'll work better, be easier to pipe, and will be more forgiving of install mistakes.
 
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Old 08-31-08, 08:41 PM
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Haven't even started the install yet, I figure if all the piping is in place, it shouldn't take too long. I'm just scoping things out and seeing if I should get a contractor to do it or not. I figure I could install it and have a contractor come to hook up the Ngas and vent it (can't legally do that in my state). It seems pretty doable. I'm working on figuring out one thing at a time. Right now, how do I run the pipes? *see below* I do appreciate all other helpful comments though .
 
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Old 09-02-08, 08:22 AM
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I have heard that for residential stuff, a low loss header isn't that effective?
 
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Old 09-02-08, 01:15 PM
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IIRC, the Vito100 manual either requires or recommends primary/secondary piping. Given that the boiler input/output is 3/4", I assume p/s in some form is probably required. The boiler is basically an injection system. The LLH is a simple solution to provide the hydraulic separation between the boiler and the distribution system, regardless of system size. Look at the Vito install manual and see which approach you prefer: full p/s or LLH.
 
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Old 09-02-08, 03:18 PM
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Yeah, the low loss header does seem like the best idea after some research. Does anyone have any recommendations for one? The only one that I have found is the B&G psh. I have made a beautiful mspaint diagram of how I understand this would be piped... if you tell me how I'm wrong, that'd be great!

 

Last edited by NJT; 09-02-08 at 03:41 PM. Reason: Jeremiah, linky no worky, I fix ...
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Old 09-02-08, 03:43 PM
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Put the pumps on the supply side.

leave like a foot of straight pipe ahead and behind the circs if you have the room ...

You should have an air scoop on there too ? Depending on the type, you MAY need 18" of straight pipe ahead of that ... some types don't require this straight pipe.

You know them PSH's are pretty pricey ...
 
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Old 09-02-08, 03:56 PM
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yeah, I'm aware of the pricey psh's, it makes me want to cry a little bit... do you have any other low loss header recommendations? The PSH is simply the only one I found online. The expansion tank or header should have something for the air, that would be adequate?
 
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Old 09-03-08, 06:36 AM
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Viessmann makes a/the LLH.
Caleffi Hydroseparator is another one.
Possibly Taco makes one as well.

Troop, the Vito loop is to be pumped on the return. I think because it has a pressure-proving switch in the boiler, and/or because they say so. This is a small hx (holds less than a gallon of water!) and they want to make darn sure the water is doing its job.

But on the space heating loops, definitely pump on the supply side. Don't use bullhead tees. Make supply and return manifolds that have the zone supplies (and returns) coming off of them. For example (from another manufacturer, but a good diagram), page 24 of this:

http://www.htproducts.com/literature/lp-185.pdf
 
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Old 09-03-08, 03:03 PM
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Originally Posted by xiphias View Post
... the Vito loop is to be pumped on the return...
That's why the install manual should be more than a kneepad!
 
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Old 09-04-08, 06:30 AM
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Ha. Yeah, not sure why I would pump into the LLH on the drawing, must've neglected that. Roger on the space between circs and air scoop. I won't be doing much zoning. Perhaps two, but I think that I will first go through a winter and figure out what the zones should even be first. I think the house in general should stay heated in a relatively even manner, as most of it is open and because of its size, the heat loss is only a little over 40,000 btus (in MN).
 
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