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Author Topic: New guy needing help  (Read 2040 times)

Dalebert

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New guy needing help
« on: February 02, 2012, 10:16:51 AM »
First I'd like to say I'm so glad I found this site...It's been a blessing to me as I have started my first build. With that said, I need some help with figuring head loss. My boiler will sit roughly 120 feet from my house and somewhere around 180 feet from the last heat exchanger. So round trip the water will be traveling 360 feet. My question is, does the water returning to the boiler(slightly downhill) act as a siphon(SP?), and in doing so, lower the head pressure loss? The way I have it figured, with 1" pex I would have roughly 30ft of head. If this is the case, I would probably need to go to a lager size pipe because I don't know if the pump I've bought(Grundfos 26-99) will handle it. I would like to stay with the 1" because of the price but I dont want to sacrifice performance. Any advice would be greatly appreciated!
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Bull

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Re: New guy needing help
« Reply #1 on: February 02, 2012, 10:24:08 AM »
Welcome to the site Dalebert, I have about a 500 feet loop going through 2 water to air hx through 3/4 inch pex with a taco pump and it works. I did not find this site before I put in my lines LOL.
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Southern Indiana
Just outside of the "Small Town"

rhugg

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Re: New guy needing help
« Reply #2 on: February 02, 2012, 10:50:38 AM »
Yes the water returning does act as a syphon so long as you get the air out.  So head is NOT lift height like you would calculate if you were pumping the water up to the top floor bath tub.  Head is only a frictional resistance that takes into account length of run, resistance of pipe used plus any valve and fitting resistance (90's etc).

You need to get, and keep your return line full of water.  You can't have small air leaks in the return line or the water column will fall back into your boiler and your circulator may not have the ability to push the coulumn up to get things going again.

If you poke around on the site you will find a link for head loss calculations for 1" PEX and fittings, but I doubt you have any problem.
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BoilerHouse

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Re: New guy needing help
« Reply #3 on: February 02, 2012, 11:48:05 AM »
I also do not think you will have a problem based on my situation.  I bought a 250 foot coil of 1 inch triple wrapped pex in big "O".   My OWB is 160 feet from the house and in addition I have a second loop from the OWB to garage which is 90 feet away.  All this is handled by a single chinese wasser pump and it all seems to work.
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Muskoka, Ont