Outdoor Wood Furnace Info
All-Purpose OWF Discussions => Plumbing => Topic started by: hoardac on April 16, 2018, 09:55:56 AM
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I have a pump question, right now I am running 2 Taco 007-F5 in series to push water through my in floor heating Would like to change to a single pump. Would a single Grundfos UPS15-58FC replace those. That is what my boiler internal circulator pump is so a spare would work for either one.
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I think a 15-58 maxes out at around 18' of head, a single 007 maxes at 10'. So together two 007's would have a 20' of head available compared to a single 15-58 with 18'. But you may not need that tiny bit extra and it would be fine.
How many loops of what size and length are you pushing? A B&G NRF-25 has a bit more flow with the same head and runs about the same price. It's a 3 speed also so is very versatile.
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I got 10 loops 1/2 pex 300ft loops but usually only 6 on at once the others are there but not usually needed.
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Checking return water temps after it's been running several days to level out would tell you if you're lacking on flow. Anything over 20F delta T would indicate dropping down to one 15-58 probably wouldn't be good.
I'd bet you'd be fine though, but I don't do radiant on an everyday basis down here in forced air land. I know there's others on here who do it all the time.
Is this in a slab? Mixed down temps?
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Unless you have a very low flow rate, a single 15-58 will not flow as much as two 007 in series. Take a look at the flow curves for each pump and double the head pressure for the 007 and you can directly compare them.
If you need the same flow rate, I would probably use a 26-99 if you want to go with a single pump. Low or medium speed would probably be pretty close to the two 007 pumps.
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I second the 26-99. 10 loops is too much for proper flow with a 15-58, although it will likely still work if you're determined to go that route. I have seen quite a few 10-12 loop systems fed with a 15-58, but the delta T is pretty huge- like 40-50 degrees. Anything over 8 loops I go to a 26-99 to keep the delta T tight. At 10 loops I go to speed 2, and at 13 loops speed 3. Did one last fall with an 8, 10, and 11 loop manifold on 3 zones. Each got their own 26-99, with the little guy on speed 1 and the others on speed 2. They balanced out to ~.70 GPM per loop and settled to a 24 degree delta T. I also run my loops 250ft max. In your case you'd be maxing out speed 2
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Thanks for all the info I will pull the 15 off the boiler and try it see if I can get same or very similar flow rates if not then I will go to the bigger pump. Never had a problem with Delta T most it ever was 13-15 degrees and that is on the coldest windiest nights. I thought 300 feet was ok to run with a 10% overage max on 1/2 inch pex. I have never had a house is to cold issue but I spaced the pex very close and extra around perimeters.