Need help with sizing circulator

[BHetrick10]

I have worked out the math for the circ on the primary loop. Now I am struggling to find a formula to figure out what I need on the actual zones.

I am putting one pump on two zones. Each zone only has two 300' loops of 1/2 pex radiant in floor.

Thanks

 

[heaterman]

Off the cuff.......you need a circ that will do 2gpm at around 3.5-4 feet of head when all 4 loops are flowing. Think small or else variable speed. A typical 007 Taco, Grundfos 15-58 or anything similar is way more than you need.

 

[BHetrick10]

Thanks Heaterman. I figured a 007 would be enough and am glad because we have one from another project.

The situation above is for a friend. I am hoping to soon get working on mine and am in the same situation, I have three different zones. Two of the zones will be using the same water temp (radiant in floor joist) the other is in concrete. I was planning on using one mixing valve and pump and two zone valves for the zones in joist I assume a 007 will work because each of those zones consist of two 300' loops of 1/2 pex. The other zone would be its own mix valve, pump it has 9 300' loops of 1/2 pex.

Would I take the total BTU for the zone and divide it by the total loops? and stilll use the same equation? I am a numbers guy and enjoy plugging in numbers to so how everything works in the big picture of things.

 

[maple1]

Simplistically speaking, are there many situations where a 'standard' 3 speed 15-58 wouldn't work? Seems to be a pretty 'universal' pump that you can speed up & down to meet pretty well any condition.

 

[Armaton]

Actually, I think he's saying a 15-58FC is too big. I have them on my system, and even on low I get flow noise. One for each zone, and each zone has 3 legs of 250-300' so his will be even more overkill. I use them because it's what I had, and if one goes bad I have an extra one on the shelf to slave in. If I read the grundfos chart correctly you get 10 gpm at 0 head and about 7at 3-4 feet?

 

[BHetrick10]

anyone? Is there an equation somewhere? Trying to get everything purchased to get rolling on the install.

 

[Karl_northwind]

google Taco TD-10, "sizing circulators"

 

[BHetrick10]

That is what I based everything else off of, but I dont see where it talks about sizing pumps on manifolds....

 

[Karl_northwind]

That's just some physics, if you're pumping 5 gpm into a manifold with 5 loops off it, you will have 1 gpm per loop (as long as they're balanced), so you take 1 gpm thru say 300' of 1/2" pex, you'll get the head for that part of the circuit. add that to the head loss of the supply and return piping (say 3/4" or 1" copper) and you get your resulting head loss for the circulator.

 

[BHetrick10]

I just did the math on it and it comes out to be a 008.

4.7 gpm / 4 = 1.175

.0374 * 300 * 1.32 = 14.8 feet of head.

look right?

 

[Karl_northwind]

those numbers look right (at laest that's what I came up with too) . of course you have to add the head of any home run piping, from the manifold back to the primary loop, at the 4.7 GPM rate. those are 300' loops of 1/2" pex right? is it Pex-Al-Pex or just regular pex? that makes a difference too.
I would recommend a 00R, as that setpoint is a little closer to the middle of the curve on medium, and you can run it on low if the performance is still adequate (in your opinion) . and it's cheaper.

karl

 

[BHetrick10]

It is just reg 1/2 " pex Head should be close the longest run is about 280'

I cant find a pump curve chart for the 00r know anywhere to find one?

 

[Karl_northwind]

It is just reg 1/2 " pex Head should be close the longest run is about 280'

I cant find a pump curve chart for the 00r know anywhere to find one?

http://www.taco-hvac.com/en/products/3-Speed Cartridge Circulator/products.html?current_category=363#

sorry, it's been replaced with the 0015 3 speed( very recently?). I'm sure you can find a 00R for sale, and a spec sheet somewhere else.

run it on medium, then on low, see if you can tell the difference. if you can't, run it on the lower speed and save some power. It really adds up over the years.

 

[BoilerMan]

I run 008s on pretty much all radiant slab runs (300' of 1/2" or 400' of 3/4") I have one 008 on a manifold that serves 5 loops of 1/2" pex. Longest run is 340' and shortest run is 260'. The manifold has flow meters and without any balancing I get 7/8 gpm on the 340' and 1gpm on the 260 footer.... I left them all alone, no need to balance, contrary to what the math says, I figured I'd try it and see what the flows did, then balance accordingly, was all good IMHO.
I'm gonna say it's about the same as a 007 but with a high head/low flow impeller. I've compaired the 007 and 008 cartridges and the 008 is thinner with more vanes and the same diameter. The wattage is almost identical.

TS

 

[BHetrick10]

Thanks for all the help.

I am trying to find a chart like this http://www.taco-hvac.com/uploads/FileLibrary/SelectingCirculators.pdf to show the pumpo curve of the 0015 and see what it looks like compared to the rest.

 

[Bob Rohr]

Thanks for all the help.

I am trying to find a chart like this http://www.taco-hvac.com/uploads/FileLibrary/SelectingCirculators.pdf to show the pumpo curve of the 0015 and see what it looks like compared to the rest.

Just "google" Taco 0015