cirulator advice please


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Old 03-15-10, 11:21 AM
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cirulator advice please

i am going to put in a new pump to replace the old and leaking and noisy B&G 100. My choices are the taco 007 and the 008. i have a 3/4" copper baseboard hot water system, 4 zones, with the longest loop having an effective length of about 350 feet. by my calcualtions, at a flow of 4 gpm, the head is 13; at 3.5 gpm it is 10. any thoughts on the 007 vs the 008? i assume i can use the current flanges with either pump? is that correct?
 
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Old 03-15-10, 11:29 AM
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I didn't check the curve but from your question the 007 would be a better choice as the 008 has a steeper pump curve. You want flatter curves with zone valves.
 
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Old 03-15-10, 11:46 AM
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Originally Posted by reisjdmd
i am going to put in a new pump to replace the old and leaking and noisy B&G 100. My choices are the taco 007 and the 008. i have a 3/4" copper baseboard hot water system, 4 zones, with the longest loop having an effective length of about 350 feet. by my calcualtions, at a flow of 4 gpm, the head is 13; at 3.5 gpm it is 10. any thoughts on the 007 vs the 008? i assume i can use the current flanges with either pump? is that correct?
Determining Frictional head can be tricky. I would use the existing pump to plot out your system head requirements.
What doesnt look right with your calcuations i=s
Head 13 =4 gpm
Head 10=3.5 gpm
As your system friction head resistance to flow decreases your gpm will increase. this is backwards from what you stated.
H1/H2 = (W1/W2)2 ........... 2 is suppose to mean squared
H= head in FT
W=GPM
Personally i would stick with the B/G pump If its a ball bearing design switching to a sleeve bearing for less noise.
B&G is a good pump, what kind of noise is it making sound like marbles? or more squeaky?
 
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Old 03-15-10, 11:52 AM
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I may have misread your post the examples of head may be for different pumps the 007 and the 008?
 
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Old 03-15-10, 03:51 PM
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Rebuild kits are available for B&G 3-piece pumps.

If your choice is to replace your pump, and the 100 was performing satisfactorily, pick a replacement with a pump curve close to the 100.

As far as flange compatibility - yes, that's a definite maybe! Check the pump dimensions available on the pump manufacturers' websites.
 
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Old 03-16-10, 08:57 AM
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sorry. my post was way too confusing.
the old B&G was installed, years ago, for only 3 heating zones [and i remote water heater]. I got rid of the wter heater andreplaced it with a 4th zone, which has the longest effective length of all [350 feet]. the B&G can handle a head of 8 at a flow of 4 gpm or less [flat curve]. this pump is now delivering only about 1 1/2 gpm in the longest zone. time to replace!!
if i want a flow of 4 gpm with the current zones, i need a pump that can handle a head of 11. the 007 cannot do this, although it can possibly handle a head of 9 at 4 gpm. the 008 can definitely do the job, but uses more energy. i do think the 007, at a flow of 3.5 gpm, can handle a head of 8.6.

so, do i get a pump slightly undersized or slightly oversized, since my design specs at 4 gpm fall between the two pumps?? is it ok to settle for 3 to 3.5 gpm flow [which is what the 007 will do]??
 
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Old 03-16-10, 09:33 AM
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Personally If would use the existing Pump as a tool to figure out what your new system head would be for selecting a pump . Increase in gpm is a increase in velocity which increases system resistance. I will make up some numbers assume that your system head now 6 FT head= 1.5 gpm
using the formula i stated before you can predict what your new head requirements are at your new GPM of 4.
select a pump on these values as mentioned as flat as possible with the highest effiecency rating.
H1= actual head ( you need to measure it ) 6
W1= actual gpm 1.4
H2 = New head ( this is what you find using the equation i mentioned previously and you need for selecting a pump.
W2= New gpm 4. ( 0r what ever you you flow requirements are. IF you size your 4 and you need 3.5 you can throttle your balancing valve to obtain your new flow rate. basically you are Increasing system head .
Inceased gpm = increased velocity which = increased frictional resistance to flow.
This way there is no guessing what kinda of system head you will have when you install a new pump, and you need to know what your new head is for selecting a pump.
Maybe overkill but this is what i would do in a commercial application. Takes the guess work out of it.
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Old 03-16-10, 09:37 AM
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Forgot to mention when selecting a Pump take a look at your NPSH this is the point your pump will cavitate if it falls below this point. Lower the NPSH the better
NPSH= Net Positive Suction Head.
 
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Old 03-16-10, 02:49 PM
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Grundfos 15-58 3-speed
Taco 00R 3-speed.

Or if you really want the cats meow, use the Grudfos Alpha
 
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Old 03-16-10, 03:49 PM
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I'm interested in those multi-speed circulators. Perhaps a slight drawback might be that efficiency would be optimum at just one speed?

One advantage would be if you were unsure of the preferred gpm/head requirements for your system. Then, you could play around with the speeds.

Or, and this is interesting to me, what about switching speeds - based on the season, outdoor reset, etc.? For systems with zone valves, the speed could be changed depending upon the number of zones calling for heat?

The possibilities seem endless.
 
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Old 03-17-10, 08:40 AM
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ok. thanks to all for your advice.
 
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Old 03-17-10, 03:19 PM
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Originally Posted by Mike Speed 30
I'm interested in those multi-speed circulators. Perhaps a slight drawback might be that efficiency would be optimum at just one speed?

One advantage would be if you were unsure of the preferred gpm/head requirements for your system. Then, you could play around with the speeds.

Or, and this is interesting to me, what about switching speeds - based on the season, outdoor reset, etc.? For systems with zone valves, the speed could be changed depending upon the number of zones calling for heat?

The possibilities seem endless.
Taco's mutli speed are said to be seperate windings, so they might be a pinch better. There is nothing to say that one could not put a relay in to automatically control the speeds based on designs. To me the Alpha would be the best bet.

I really don't think they lose much due to the speed changes, I am no pump engineer but I would imagine everything has be optimized.
 
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Old 03-25-10, 02:32 PM
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Originally Posted by Mike Speed 30
I'm interested in those multi-speed circulators. Perhaps a slight drawback might be that efficiency would be optimum at just one speed?

One advantage would be if you were unsure of the preferred gpm/head requirements for your system. Then, you could play around with the speeds.

Or, and this is interesting to me, what about switching speeds - based on the season, outdoor reset, etc.? For systems with zone valves, the speed could be changed depending upon the number of zones calling for heat?

The possibilities seem endless.
I totally agree with you. There are a lot of possibilities and the only way to find out is to make a good choice.
 
 

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