Grundfos circulator "Setting" question..

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Old 11-19-08, 05:57 AM
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Grundfos circulator "Setting" question..

Have a question on the settings on my Grundfos circulators. They can be set as Low/Medium/High as far as circ speed/flow. Two questions. First, as to comfort. Does the higher circulator flow mean that the hot water baseboard is putting out slightly more heat? And second, if the water flow circ is increased, am I using more oil? I guess the default setting is in the medium position. I am curious about the Low and High settings....Thanks, Bill (Sorry if I asked this question before, I don't recall a reply.
 

Last edited by bostonfan49; 11-19-08 at 05:59 AM. Reason: follow-up
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Old 11-19-08, 08:16 PM
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Does the higher circulator flow mean that the hot water baseboard is putting out slightly more heat?
Ummmm... no, and maybe yes ... if the flow is too low, and/or the baseboard run is rather long ... you would probably get a little bit more out of the baseboards near the END of the loop. The higher flow will mean that there will be slightly hotter water at the END ... the water at the beginning is still the same temp, so the effects there will be minimal. But on a well designed system, I doubt you would notice.

if the water flow circ is increased, am I using more oil?
That's a trick question ... in a very small way, you are, but at the power plant, if they burn oil to generate electricity ... because the higher speed will use slightly more electricity, but you won't burn any more/less fuel oil. Even if you did, I highly doubt you would be able to measure the difference.

The speed of the pump should be such that flow velocity is between 2-4 Feet Per Second. This will be fast enough to remove trapped air bubbles, and not so fast that you will hear the water running, or scour the inside of the pipes until they leak.

At that flow rate, in a properly designed system, the difference in temperature between the supply and return will be around 20 degrees F ... a slower pump speed will INCREASE that difference, and a faster speed will DECREASE it. You could put thermometers on both the supply and return ... or,

just set them on medium and enjoy the warmth!
 
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Old 11-24-08, 07:23 AM
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..thanks NJ! Set to medium. By the way, With the OR, the boiler temp has yet to come up over 148-150F even with the outdoor temps as low as 18-20F, and we are toasty. I am beginning to wonder when I will see a higher boiler temp...hope I don't! Its early yet so far I calculate I have saved about a 100 gallons of oil.... Thanks, Bill
 
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