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Motors do work harder under load.... Posted by Herb Hirsch [Email]  (#114)  [Profile/Gallery]
(more from Herb Hirsch) on Fri, 7 Sep 2007 12:55:05
In Reply to: Re: HVAC High End Filter (3M) or Cheap Blue Filter?, OKSaabs, Fri, 7 Sep 2007 06:25:53 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Blower motors on HVAC systems are usually AC synchronous motors. Motors of this type turn at a constant speed determined by the frequency of the AC voltage applied (60 hertz in the US).
If the load on the motor increases (eg.: a finer filer) the motor will draw more current in an effort to remain synchronous with the frequency of the AC voltage aplied.
Everything works wonderfully as long as the load on the motor is within its design load parameters. Well designed HVAC systems will use a motor that is overrated by a factor of 2-4. Hence, the opinion that a change to a finer filter putting a higher load on the blower motor is of no consequence...the load on the motor is still within its design parameters. A clamp typ AC ampmeter is one way of determining the load on the motor by measuring current used and comparing this with design load information.
If the load on the motor exceeds the load design parameter the consequence is a motor that runs hot (no warm which is normal....but, burn your hand hot). The more you exceed the maximum load parameter of the motor the hotter it will run. In an overloaded state the consequences are shortened motor life, blown circuit breaker, fire, poor performance.
HVAC blower motors get an added benefit in that they are placed in a moving air stream...this helps to keep them cool and prolong their life. It does not mitigate/prevent the consequence of heavily overloading a motor.
Finally, I have been using a high-end 3M filter in my home HVAC system for 8 years....no problems. And yes, I felt the motor after a couple of hours of continuous operation....it was cool.
posted by 205.188.11...
, Fri, 7 Sep 2007 12:55:05 <-- Viewing This Message
, Thu, 6 Sep 2007 09:50:07, Thu, 6 Sep 2007 05:58:00
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