dstutz
New Member
I am planning on replacing the polybutylene pipe in my house with PEX-A basically using Uponor's "Structured Plumbing" recommendations. I'd like to add an on-demand recirculation system while re-piping. I have a ranch house with everything on one level, the pipes run in the crawlspace under the joists (hot and cold are fully insulated and I plan to continue that). The main hot water trunk and the return will be 3/4" using flow-through manifolds. I was planning on using a Taco 006-ST4 pump triggered via timer-relays (ie run for X seconds after switch is pressed then turn off, where X is the time it takes to get hot water to the T/manifold serving the fixture). I'm on a well, the pressure switch runs between 30 and 60psi.
006-ST4 pump specs:
HP: 1/40
Flow Range: 0 – 11 GPM
Head Range: 0 – 9.5 Feet
I've calculated very roughly/generously 75' of pipe to get to my farthest fixture (master bath, which of course is allllll the way on the other end of the house from the WH). Once the line goes down into the crawlspace I plan on only using 90 bend supports and no elbows in basically the whole hot supply/return loop (Actually, I lied. I think I have to use one T (to house a vacuum relief valve) which will function as an elbow for the water flow back into the WH), all fixtures will be T'd off the main 3/4" line. The return line should be ~60-70'.
I'm a little out of my element on calculating "head", pressure loss, friction loss and whether this pump is "too much"or "not enough" for my situation. I've looked at the Uponor pressure loss tables and Hydronic friction loss tables and I'm just scratching my head.
In the Uponor pipe sizing document for domestic hot water piping it recommends:
Maximum velocity of 12 ft./sec. through pipe
Recommended velocity of 8 ft./sec. through pipe
Another document details for the 3/4" fittings:
6.9gpm @ 8ft/sec for brass (6.8gpm plastic)
10.4gpm @ 12ft/sec for brass (10.2gpm plastic)
Since the pump can do 11gpm is this a problem or no, because the pump won't actually move water that fast due to the ~140' of pipe in the whole loop and friction losses? On the contrary, is this pump powerful enough? Should I go bigger (would a 007-SF5-IFC be too much)?
I recently came upon the D'MAND Kontrols® Systems by ACT C3-100 which uses a 0-18GPM pump using the same 3/4" connections....so am I overthinking this/worrying about nothing?
Thanks,
Dave
006-ST4 pump specs:
HP: 1/40
Flow Range: 0 – 11 GPM
Head Range: 0 – 9.5 Feet
I've calculated very roughly/generously 75' of pipe to get to my farthest fixture (master bath, which of course is allllll the way on the other end of the house from the WH). Once the line goes down into the crawlspace I plan on only using 90 bend supports and no elbows in basically the whole hot supply/return loop (Actually, I lied. I think I have to use one T (to house a vacuum relief valve) which will function as an elbow for the water flow back into the WH), all fixtures will be T'd off the main 3/4" line. The return line should be ~60-70'.
I'm a little out of my element on calculating "head", pressure loss, friction loss and whether this pump is "too much"or "not enough" for my situation. I've looked at the Uponor pressure loss tables and Hydronic friction loss tables and I'm just scratching my head.
In the Uponor pipe sizing document for domestic hot water piping it recommends:
Maximum velocity of 12 ft./sec. through pipe
Recommended velocity of 8 ft./sec. through pipe
Another document details for the 3/4" fittings:
6.9gpm @ 8ft/sec for brass (6.8gpm plastic)
10.4gpm @ 12ft/sec for brass (10.2gpm plastic)
Since the pump can do 11gpm is this a problem or no, because the pump won't actually move water that fast due to the ~140' of pipe in the whole loop and friction losses? On the contrary, is this pump powerful enough? Should I go bigger (would a 007-SF5-IFC be too much)?
I recently came upon the D'MAND Kontrols® Systems by ACT C3-100 which uses a 0-18GPM pump using the same 3/4" connections....so am I overthinking this/worrying about nothing?
Thanks,
Dave
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