On Tuesday, February 12, 2019 at 9:14:49 AM UTC-5, Scott Lurndal wrote:
Clare Snyder writes:
On Mon, 11 Feb 2019 16:35:25 -0500, Tekkie®
wrote:
Clare Snyder posted for all of us...
On Wed, 6 Feb 2019 14:02:53 -0500, Tekkie® wrote:
Frank posted for all of us...
On 2/4/2019 7:23 PM, Ed Pawlowski wrote:
For the first time in 53 years of owning homes, my new house has a
furnace and uses filters.Â* It takes a 1" filter.
I see prices can vary considerably but is a MERV 8 and MERV 8 regardless
of the brand?Â* Should I use MERV 8 or MERV 11?Â* We have no pets.
I see filters with MERV 11 rating from $9.95 ($7.45ea by a dozen) to
$14.50. Any real difference if they have the same rating?
Discount filters seems cheapest.
I use air filters and had never heard the term MERV so looked up your
question:
https://airexpertsnj.com/knowledge/e...erv-11-filters
Prompted me to look at the filters I'm using and now see that they are
MERV 11. Don't know about price difference but sometimes filter may
collapse somewhat and more expensive filter might be sturdier.
I am no filter expert but IIRC if the MERV number is increased then possibly
the blower motor can overload. Research the info on your system to determine
the suitability.
Restricting airflow does NOT overload a blower motor. Restricted
filters restrict the amount of air moved REDUCING load on the blower
motor. Youknew that and forgot - right "tekkie"?
If I am wrong then teach me. I have always been willing to listen.
Plug your vacuum hose and listen to the pitch of the motor. It speeds
up. Power is consumed by moving air. Block the filter and you move
less air, therefore using less power. It's not like a positive
displacement pump like a compressoe - where you WOULD be correct.
One problem with blocked air filters and plugged vacuums (without a
bypass motor) is overheating because less air moves across the motor
to cool it. It overheats not from overloading but undercooling.
I hope that "clare"ifies things for you.
Don't take my word for it.
look at
https://www.cagi.org/news/HowInletCo...pressors. pdf
look at the intake pressure section on page 3 - just after figure 2.
I thought we were discussing furnace filters. What does an
air compressor have to do with it?
The facts are that the air handler in the furnace needs to work _harder_
when the filter gets dirty. Working _harder_ requires more current.
It would seem to me there are two competing factors. Clare says that a
fan with a dirty filter moves less air, so that means less current. That
certainly would be true, all things being equal. You raise a good point
though, that it's not necessarily just about how much air is moved, but
the force required to pull what air it's moving. If I'm lifting 30
1 lb balls a minute off the floor, it takes X power. If I'm lifting only
20 1 lb balls a minute, it takes a third less power, 0.66X. But if I'm lifting
20 1 lb balls and they are being held back now with a small spring,
representing a dirty filter, then
the power used will be more than .66X. I think in the real world, for an
ordinary blower motor, with a restricted filter it does wind up using less
power with a clogged filter. Ultimately if you clog if enough, the blower
winds up cavitating and the power drops even more. The new ECM, variable
speed blowers though, I think behave differently and may use more power
with a clogged filter.