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post #1 of 6 Old 07-28-2020, 10:49 PM Thread Starter
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HVAC guys here?

I’m needing to replace the blower motor in the air handler for my oil burner/Air Conditioner.

To ensure that I wired the new motor properly, I read the schematics and noticed that it’s currently wired differently than the schematic in the installation guide.

The unit is currently wired to have the blower on high for both heat and cooling.

The schematic shows high for cooling and medium high for heat.


It’s always been my understanding that lower speeds make heat feel more comfortable, so is there any reason not to set the blower speed for heating to medium high for heat instead of high?
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post #2 of 6 Old 07-29-2020, 07:50 AM
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I am not a HVAC guy.



Why not wire it with a single pole double pole switch so you have a winter speed and a summer speed for the blower. And yes a slower blower speed for heat is more comfortable. I had this same situation some years ago with a heat pump system. The house felt drafty in the winter where the blower was wired when the unit was installed.
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post #3 of 6 Old 07-29-2020, 07:53 AM
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we have a sister website called DIY Chatroom.
there is a specific section for HVAC questions where trade
professionals are there to help.

.

there is no educational alternative to having a front row seat in the School of Hard Knocks.
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post #4 of 6 Old 07-29-2020, 08:28 AM
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Quote:
Originally Posted by Quickstep View Post
Iím needing to replace the blower motor in the air handler for my oil burner/Air Conditioner.

To ensure that I wired the new motor properly, I read the schematics and noticed that itís currently wired differently than the schematic in the installation guide.

The unit is currently wired to have the blower on high for both heat and cooling.

The schematic shows high for cooling and medium high for heat.


Itís always been my understanding that lower speeds make heat feel more comfortable, so is there any reason not to set the blower speed for heating to medium high for heat instead of high?
In order to accurately set the blower speed for heating, you need to take a temperature rise. The blower may have been set to high to overcome a shortfall with the ductwork. If its performed adequately, wire it the same.

Furnace blowers have between 3 and 5 speeds typically, and selection is based on field conditions.

Sent from my SM-G930V using Tapatalk

Dave H
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post #5 of 6 Old 07-29-2020, 08:29 AM
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The lower the blower speed the higher the temp rise across the furnace.

Sent from my SM-G930V using Tapatalk

Dave H
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post #6 of 6 Old 07-29-2020, 12:36 PM Thread Starter
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Originally Posted by furnacefighter15 View Post
The lower the blower speed the higher the temp rise across the furnace.

Sent from my SM-G930V using Tapatalk

Thanks for this incredibly useful answer. It's all adding up now. As I recall (and my memory ain't that great), I think the unit was shipped with a .75gph tip, but it short cycled, so we switched to a .65 tip. The schematic says to use the High blower speed for the .75 tip and Med-Hi for the .65 tip. It sounds like I could use med-high if I wanted to, but if someone ever went back to the .75 tip it could over heat. Since it's kinda old, sounds best to stay with high for the blower to avoid killing the heat exchanger.
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