Blower Motor for Rudd UGPH-07EAUER, 1/2hp to 3/4


Old 07-15-13, 04:19 PM
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Join Date: Jul 2013
Location: canada
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Smile Blower Motor for Rudd UGPH-07EAUER, 1/2hp to 3/4

Hi all!
just a quick question I hope...
my Rudd 75000btu gas furnace has a 1/2hp blower motor which seems to work fine except that it takes forever to cool the house down in the summertime. I pretty much have to leave the fan on all the time to keep the house at a comfortable temp. The air temp seems cold enough, so I'm thinking that more airflow/pressure would solve the problem. From the manual, it looks like the 1/2hp and 3/4hp furnace models are identical, same BTU's except more airflow of course. I'm wondering if this is a viable option? would any of the wiring change? control board? Any ideas??? manual says the blower motor is 11 x 7 for the 3/4hp instead of 11 x 6 for the 1/2. Where can I buy the larger motor...? Home Depot?
Thanks for any help!
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Old 07-15-13, 06:16 PM
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Join Date: Jan 2011
Posts: 6,245
Air flow must be set at 400 cfm per ton (12,000 BTU) of cooling. The outdoor unit will have the btu rating in the model number. Post that model number. Also post the model number of the furnace. Changing the fan speed in cooling will effect the dehumidification that the a/c does and not necessarily effect how quickly the house cools down. I strong advise against doing as you propose.

11 X 7 indicates the size of the blower wheel and not the size of the motor which is why the larger motor is required for the larger wheel. Box stores will have nothing in way of a replacement motor.

It would be in your best interest to make sure all filters are clean and all coils are clean as a first step in trying to improve cooling.
Old 07-17-13, 10:44 AM
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Join Date: Jul 2013
Location: canada
Posts: 3

Hi Kevin,
Thanks very much for your reply. I understand what you are saying. I will check the outdoor unit for more info. Thanks for the suggestions, I never thought to check the coils inside the furnace. I should give it all a good cleaning!!!
Old 07-17-13, 03:26 PM
Join Date: Oct 2008
Location: USA
Posts: 2,815
Increasing the motor from 1/2 to 3/4 hp probably would change the air flow insignificantly driving the existing fan. The speed of the higher hp motor would be just a tad higher (due to slightly lower slip) - so the original fan will still run essentially at the same speed. Do some googling of induction motors to better understand this.
Old 07-18-13, 11:28 AM
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Join Date: Jul 2013
Location: canada
Posts: 3
Thanks gilmorrie. I'll check that out.

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