Tony Hwang wrote:
harry wrote:
On Mar 29, 1:18 am, Tony wrote:
wrote:
On Sun, 28 Mar 2010 17:09:05 -0600, Tony
wrote:

Hi,
When I was replacing blower motor on our furnace
there were two replacement choices 1.0 Hp or 3/4 Hp 3 speed
motor. Between two only difference was Hp rating and full load
current draw. As sn after thought I wonder if there'd be any advantage
choosing the 1.0 Hp one. BTW, our a/c unit is 3.5ton.
TIA for any experienced comments.

You really should be consulting the installation documentation of your
system. That is not as simple as just saying bigger is better.
The air handler and the condenser have to be matched.

Hmmm,
Not knowing anyting HVAC. I put in 3/4 Hp one as the manual states.
But curious duck wannna learn. Any pointers where to look? Getting
old guy has to exercise his brain, LOL!

So long as the motor is not exceeding it's rated current (Amps)
depicted on the nameplate, there is no need to worry. There is no
point in putting in an oversized motor. So, if you're worried, you
need to borrow a meter that can read amps& check it out. But if it
was 3/4 HP before, it's gonna be 3/4HP again.
Hi,
Original motor spec. is 3/4, 2/1, 1/3 Hp, 3 speed of which first two
speed are used high speed for cooling and medium for heating.
The 1.0 Hp motor had 1.0, 3/4, 1/2, 1/3 Hp 4 speed. My thought was
with this motor I could have more options.

If the 3/4 HP motor is large enough you don't need the extra power. Then
the comparison is the different motor speeds. I would be cautious
changing RPMs from the manufacturer options.

Also this motor had ball
bearings vs sleeve bearings. I understand ball baerings last longer.
Any how furnace is back up and running again.

Sounds reasonable.

Some motors are more efficient than others. Electric cost can swamp out
value of different lifetime and cost of a higher efficiency motor.

Next is time to replace it
when breaks again. Price difference was like ~40.00

I believe, other things being equal, the 3/4 HP motor run near its
rating is more efficient than a 1HP motor run below its rating.