P/S confusion....

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Old 11-22-08, 05:53 AM
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P/S confusion....

In an earlier posting rbeck sent a link to this page http://www.comfort-calc.net/primary-..._tutorial.html where drawing #6 says

1. the distance from the closely spaced tee to an elbow is a minimum of 4x primary pipe diameter

2. distance from an elbow to the closely spaced tees is a minimum 8x primary pipe diameter


After browsing the site I ran into this page circulator_sizing where the image says

1. the distance from the closely spaced tee to an elbow should be
4x primary pipe diameter or less

2. the distance to the closely spaced tees should be kept as close as possible.


One diagram is telling us to use more distance and the other is telling us to use the least amount of distance, can someone clarify this?
 
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Old 11-22-08, 07:06 AM
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The distance from an elbow to closely spaced tees is a minimum of 8 times the diameter of the primary pipe, the distance from the set of closely spaced tees to another elbow is a minimum of 4 times the diameter of the primary pipe. The distance between the closely spaced tees is a maximum of 4 times the diameter of the primary pipe not to exceed 12" but the closer the better.
 
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Old 11-22-08, 09:09 AM
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IOW,

The pipe flowing TOWARD the CSTs should be at LEAST 8D.

The pipe flowing AWAY from the CSTs should be at LEAST 4D.

BETWEEN the CSTs, no more than 4D, closer/better.

>>>>>>>>8Dmin>>>>>>>>T>>4Dmax>>T>>>>4Dmin>>>>
 
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Old 11-22-08, 01:49 PM
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Thanks trooper. I am glad you can assist as rapidly as you can.
ZIZANZIO Any other questions See drawing 6
http://www.comfort-calc.net/primary-..._tutorial.html
 
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Old 11-23-08, 06:38 AM
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Drawing 6 says
"The boiler piped as secondary piping would also follow the distance
between the closely spaced tees as per drawing #3 or #4." does this mean
>>>>>>>>8Dmin>>>>>>>>T>>4Dmax>>T>>>>4Dmin>>>>
from and to the boiler? If yes what if there are multiple boilers, is it the ,measurement from the closest fitting to the tees?
 
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Old 11-23-08, 10:06 AM
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I think I'd shoot for at least 12D [edit: I should have said 8D] between pairs of tees ...

You're planning on 'staging' the boilers I presume?

rbeck? is 12D correct ? never mind ...
 

Last edited by NJT; 11-25-08 at 05:00 PM. Reason: my bad
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Old 11-24-08, 09:56 AM
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Yes staged boilers is the plan...

12d is from the cst to the boiler supply/return tee/connection?

Originally Posted by NJ Trooper View Post
I think I'd shoot for at least 12D between pairs of tees ...

You're planning on 'staging' the boilers I presume?

rbeck? is 12D correct ?
 

Last edited by NJT; 11-25-08 at 05:02 PM. Reason: grayed out... see previous post
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Old 11-24-08, 02:30 PM
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Not sure what yer askin' there Ziz ... ?

12 D between pairs of CSTs ... but you could probably get away with 8 D between the pairs of CSTs...

>--8Dmin--TEE--4Dmax--TEE--4Dmin--|>--8Dmin--TEE--4Dmax--TEE--4Dmin--etc ...

but to save space, 8 D between the pairs (sets) of CSTs like this ...

>--8Dmin--TEE--4Dmax--TEE--8Dmin--TEE--4Dmax--TEE--4Dmin--etc ...
 

Last edited by NJT; 11-25-08 at 05:03 PM.
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Old 11-25-08, 01:24 PM
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What I am asking and I dont know if it makes a differance or not maybe someone can help out here is does the distance between the cst and the elbow/tee towards the boiler play a role in this drama?
 
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Old 11-25-08, 04:53 PM
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I think the answer is yes ...

Lemmee try this another way:

A pair of closely spaced tees must be installed in a STRAIGHT run of pipe. This run of pipe should be AT LEAST 8D going IN, and 4D coming OUT of the tees.

example, using 2" pipe, flow from left to right:

ELBOW - 16" nipple - TEE1 - TEE2 - 8" nipple - ELBOW

as always, the tees are as close as practicable, not to exceed 8"

if you had multiple sets of tees in a straight run, I _think_ 8D is ok between them:

ELBOW - 16" nipple - TEE1 - TEE2 - 16" nipple - TEE3 - TEE4 - 8" nipple - ELBOW
 
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Old 11-25-08, 06:11 PM
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OK, understood..

Again, what I am asking and I dont know if it makes a differance or not is does the distance between the cst and the elbow/tee towards the boiler play a role in this drama?

I am talking about the piping that comes off the center tees and goes to the boilers.
 
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Old 11-25-08, 07:23 PM
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Once you come off the tees to the boiler there are not distance requirements. Pipe all boilers into one set of close spaced tees. see link first drawing.
Multiple_boiler
From one set of cst's to another set of cpt's only need to be 6" - 8".
 
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Old 11-25-08, 07:39 PM
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rbeck, is it safe to assume that all the circs in those multiple boiler diagrams would be of the IFC (Internal Flow Check) type ?

Sorry Ziz, I didn't get what you were askin' cuz I'm dense sometimes ... I understand now though ...
 
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Old 11-26-08, 01:51 PM
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Buderus has it so that if you are using multiple boilers each boiler users its own set of CSTs, whats the story here guys? Is there a differance between using a manifold type system and separate tees?
 
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Old 11-28-08, 01:41 AM
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also....

What role does the spacing play after and before the cst?

and...

I am using 2" piping and need to loop back around using 2 elbows and a close nipple, is this too much stress and should I be doing this differently?

Thanks all
 
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Old 11-28-08, 05:53 AM
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Dan Holohan has a nice book called Primary/Secondary Piping Made Easy. Addresses nearly everything you've asked, including multiple boilers. Check it out.
 
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Old 11-28-08, 07:16 AM
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Speaking of books... another very good one would be "Modern Hydronics" by John Siegenthaler ... it's a textbook of everything and anything to do with hydronics... your local library may have a copy if you want to 'try before you buy' .
 
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Old 11-30-08, 12:29 PM
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...more on P/S sizing

Gentlemen, how does this look for starters?

My concern is the double elbow with the 2" close nipple on the far left.


<a href="http://s447.photobucket.com/albums/qq191/zizanio0/?action=view&current=P-S.jpg" target="_blank"><img src="http://i447.photobucket.com/albums/qq191/zizanio0/P-S.jpg" border="0" alt="Photobucket"></a>
 
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Old 11-30-08, 03:04 PM
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What role does the spacing play after and before the cst?
The closely spaced tees operate on the premise that there is little or no pressure difference between the two side ports. When there are elbows and things too close to the tees, they upset the pressure balance between them. Allowing the water a 'straight shot' into and out of the tees gives the pressure in the pipe room to 'stablize' before it runs past the tees.

I am using 2" piping and need to loop back around using 2 elbows and a close nipple, is this too much stress and should I be doing this differently?
Probly be all right ... too much 'stress' ? whatcha mean ?
 
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