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I was told that esp should be taken distance of 2.5 times the diameter of the blower wheel from the center of the blower shaft.
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But if you look closely at the manufactures info you'll find that YORK for instance , gives ESP values WITHOUT filters And very intelligently then gives some instruction as to why you may for instance need 2 return elbows and filters for say a 5T unitOriginally Posted by JBM1000
You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!
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Your's
I think the underlined sentence agrees with " result in higher operating costs the system is working more." that you said you disagree withI disagree that dirty filters etc. result in higher operating costs the system is working more. It is actually working less. Take a blower and run it wild with no restrictions....amps go up. Stick board in front of the outlet and restrict flow and amps go down...it's moving less air and doing less work. Your losing efficiency, which wastes energy and is a loss of efficiency causing the system to run longer.
But I like your point about amp draw. Counter intuitive isn't it!
You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!
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When a furnace tune-up is being performed by reputable person/agency do they undertake such static pressure tests in supply and return and thus adjust (if possible) accordingly? Or, this is something completely out of the purview of maintenance?
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With a constant cfm ECM blower the amps will go up as the filter becomes restrictive.
I assume that Gib's Son was responding to Desuperheater's statement. But here's what he actually said "Less ESP at equal CFM means the blower is working less, might last longer and will use less energy." Which is correct. HTH.
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determined at installation and bench marked. It should be checked on each maintenance call to help determine if the system is functioning propperly.
Most companies will not check it because they do not know what it should be, or where to take the measurements.
Reputable person/agency is a relative term.
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Originally Posted by genduct
I think the underlined sentence agrees with " result in higher operating costs the system is working more." that you said you disagree with
But I like your point about amp draw. Counter intuitive isn't it!
BUT I believe the counter intuitive situation we mentioned should still be true even though the more efficient, and smarter moptor is going to try to hunt for the "sweet spot' delivering the CFMs it want to "shovel" into the duct system
You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!
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The original discussion did not mention an ECM motor. That being said, I would have to run my own real world test to confirm ( in my mind) that amps would go up as ESP increases with an ECM motor in order to believe it. I have never tested this. On the surface it sounds logical, but before I ran real world test's on non-ecm motors, I never believed that more static = less amp draw either.
Politicians need to be changed like diapers, and for the same reason.
Mark Twain
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[QUOTE=Gib's Son;11478882]The original discussion did not mention an ECM motor. That being said, I would have to run my own real world test to confirm ( in my mind) that amps would go up as ESP increases with an ECM motor in order to believe it. I have never tested this. On the surface it sounds logical, but before I ran real world test's on non-ecm motors, I never believed that more static = less amp draw eitherOTE]
His statement was valid for PSC motors too, given that he specified "at the same cfm."
What he meant, best I can tell, is that given the choice of a lower speed tap and and a lower ESP vs. a higher speed tap and a higher ESP, the former would consume less energy "at equal cfm."
The fan laws will tell you the same thing.
I brought up the constant cfm ECM blower because it's a more direct example of this effect.
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And you are right I misread your quote "With a constant cfm ECM blower the amps will go up as the filter becomes restrictive" and now agree that as the Smart ECM ramps up RPM trying to maintain CFMs it will use more watts to do it.What he meant, best I can tell, is that given the choice of a lower speed tap and and a lower ESP vs. a higher speed tap and a higher ESP, the former would consume less energy "at equal cfm."
Good call, I should read more slowly I heard you without listening
You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!
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Thank you all who responded to answer my original post. Now I have another question:
The static pressure rating that is located on the manufacturers plate is that SP as it pertains to the unit operating in the fan or cooling mode?
Since that heat operation is on a lower speed than cooling what pressure should I be looking for in regards to the manufacturers specs and installation design?
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