HW Boiler > Supply Header > Circ Pumps - Where to Reduce Pipe Size?
#1
Member
Thread Starter
Join Date: Jan 2014
Location: United States
Posts: 30
Upvotes: 0
Received 0 Upvotes
on
0 Posts
HW Boiler > Supply Header > Circ Pumps - Where to Reduce Pipe Size?
I am planning a hot water oil-fired boiler replacement, 2 zones w/circ pumps + an indirect. I am moving circ pumps from return to supply side. So the near boiler supply piping is 1-1/4" NPT but should that be reduced somewhere before it gets to the circ pumps off the supply header? Or is it 1-1/4" including the supply header and off that going to each Circ pump, is that where I reduce it down to 1" or 3/4" at the input of the Circ pumps? Of course the output of the circ pumps will be 3/4".
In looking at the old installation it appears it was 1-1/4" to the input of the air separator and reduced 1" on the output, and then each zone off that was reduced to 3/4".
thanks for all the input
In looking at the old installation it appears it was 1-1/4" to the input of the air separator and reduced 1" on the output, and then each zone off that was reduced to 3/4".
thanks for all the input
#2
Member
Thread Starter
Join Date: Jan 2014
Location: United States
Posts: 30
Upvotes: 0
Received 0 Upvotes
on
0 Posts
In looking at some installation pics it looks like I can reduce down to 1" after the near boiler piping, and before the air separator. Supply manifold would be 1" with 3/4" pipes going up to the circ pump input.
#3
A general rule that most installers follow is that when feeding a pair of certain pipe size, the feed pipe should be one size larger.
So, two 1/2 into 3/4
two 3/4 into 1
four 1/2 into 1
two 1 into 1-1/4
four 3/4 into 1-1/4
eight 1/2 into 1-1/4
So you are fine feeding two 3/4" loops from a 1" manifold. Are you sure you're never going to expand? You'll never, ever, need another 3/4" feed, say for an indirect?
There's nothing at all 'wrong' with feeding a pair of 3/4 from 1-1/4 and adding a couple of 'stubs' to the manifold for future expansion!
Some guys figure that if there are 4 zones, the chances that they will all call at the same time are sorta slim, and will go with 1" feeding four 3/4", just to save a couple bucks on the copper, but for 1-1/4 you will probably be using steel anyway... so why not do it 'right'?
SOME overkill is not a bad thing!
This assures that flow velocity in the pipes remains around 4 feet per second, which is considered about optimum.
Above this size, things change a bit...
So, two 1/2 into 3/4
two 3/4 into 1
four 1/2 into 1
two 1 into 1-1/4
four 3/4 into 1-1/4
eight 1/2 into 1-1/4
So you are fine feeding two 3/4" loops from a 1" manifold. Are you sure you're never going to expand? You'll never, ever, need another 3/4" feed, say for an indirect?
There's nothing at all 'wrong' with feeding a pair of 3/4 from 1-1/4 and adding a couple of 'stubs' to the manifold for future expansion!
Some guys figure that if there are 4 zones, the chances that they will all call at the same time are sorta slim, and will go with 1" feeding four 3/4", just to save a couple bucks on the copper, but for 1-1/4 you will probably be using steel anyway... so why not do it 'right'?
SOME overkill is not a bad thing!
This assures that flow velocity in the pipes remains around 4 feet per second, which is considered about optimum.
Above this size, things change a bit...
#4
I just noticed you're doing an indirect in addition to the 2 zones.
You really should pipe the indirect in ONE INCH if you wanna do it right.
I would probably do this with 1-1/4 black, take a 1" off for the indirect as the first tap on the manifold after the boiler, then the two 3/4" zones after that.
You really should pipe the indirect in ONE INCH if you wanna do it right.
I would probably do this with 1-1/4 black, take a 1" off for the indirect as the first tap on the manifold after the boiler, then the two 3/4" zones after that.
#5
Member
Thread Starter
Join Date: Jan 2014
Location: United States
Posts: 30
Upvotes: 0
Received 0 Upvotes
on
0 Posts
This is the kind of info I need Trooper... thank you. I will be feeding 3 circ pumps (2 heating zones plus indirect HW tank) off the manifold plus I will add one stub for future expansion. By the guidance given it seems I should have a 1-1/4" supply header and the pipe going to each circ will be be 3/4."
#6
Member
Thread Starter
Join Date: Jan 2014
Location: United States
Posts: 30
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Indirect HW Pipe Size
You are saying pipe my whole indirect supply and return paths with 1" vice 3/4"? I was trying not to touch the indirect piping with the boiler change.
#7
You are saying pipe my whole indirect supply and return paths with 1" vice 3/4"? I was trying not to touch the indirect piping with the boiler change