Author Topic: Low Air Flow  (Read 441 times)

Offline steve_togo

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Low Air Flow
« on: September 18, 2018, 04:52:21 PM »
Hello everyone,

I am a newb here and I would like some help. We had a new Furnace and AC installed last year
EL296UH070XV36B
14ACXS030-230A22   

I believe its a 2.5 ton AC unit. All my jumpers on the furnace board are at the default setting and as per the manual the default setting would yield around 800 CFM. I see a lot of posts online as to 400 CFM per ton guidelines. We experience very low air flow, What is the best way to increase the air flow. I did see a post asking to wire the Y1 from the thermostat to the Y2 of the furnace board. I am curious as to how this will work as the the connection to the outside condenser is from Y1 on the furnace board. I do have an Ecobee4 TS.

Thanks,
Steve

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Re: Low Air Flow
« Reply #1 on: September 18, 2018, 07:22:05 PM »
That other post was wrong.  Y1 is what you use and the default second stage cooling CFM is 1230.  You only need 1000 CFM.  You could boost the cooling airflow by 10% to 1355 by turning dip switch #7 to ON.

The control board should display the CFM.  Pull the front door off and look through the window in the bottom door.

Quote
Cooling stage (1 second ON, 0.5 second OFF) / 1 or 2 displayed / Pause / cfm setting displayed / Pause / Repeat codes).

You may just have an ductwork problem or maybe the AC coil above the furnace is dirty.

Offline steve_togo

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Re: Low Air Flow
« Reply #2 on: September 18, 2018, 09:47:17 PM »
Thanks for the quick response, how can I get 1265 cfm when I am using only a single stage compressor. I live in Michigan and do you think the cfm I have now is good? I have attached the blower data for my furnace and based on the table I don’t see how I can get to 1000 unless I connect the outdoor unit and thermostat yo y2 on my furnace board and reduce the airflow by 10%. Is that what you are suggesting I do?

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Re: Low Air Flow
« Reply #3 on: September 19, 2018, 08:02:25 AM »
Well I thought you wanted to increase the airflow.  Have you checked the control board to see what CFM the fan runs at in cooling?

You’re looking at the chart with bottom return air.  I was using the chart with single side return air.

If you use a single stage AC then the second stage cooling column is what you use, not the first stage cooling column.

If someone cut the W915 jumper for two stage cooling just wire the AC to Y1 and install a jumper wire between Y1 and Y2 on the furnace board.

If it’s a 2 storey house using the high speed second stage cooling speed should be fine.  I’m not sure what’s causing the low airflow.

Offline steve_togo

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Re: Low Air Flow
« Reply #4 on: September 20, 2018, 11:16:29 AM »
Thanks for the detailed info.

I did not realize it runs a single stage AC with a 2nd stage fan CFM in the default mode. My house is an 1800 SQFT 2 floor home and I was not getting Enough AC in the second floor, The air was not cool enough. I have now slowed it down to run at 1050 CFM and its 2.5 ton AC, Do you think I could freeze the coil when running at that speed. I am not sure if  the CFM number shown at the furnace is accurate, are those numbers theoretical numbers or is that the CFM i will always get in spite of ESP because its a ECM motor.

Thanks,
Steve

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Re: Low Air Flow
« Reply #5 on: September 20, 2018, 11:45:53 AM »
You should be able to use 875 - 1000 CFM without problem.

That's a good question, I'm not sure if that's a real CFM reading or just a calculated one.  I suspect if you throw in a very dirty filter it would still display the same CFM even though we know it's reduced.

Offline steve_togo

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Re: Low Air Flow
« Reply #6 on: September 20, 2018, 03:59:22 PM »
You are correct, I did have a dirty filter before and i recall showing the same values. But i thought it is correct because a ECM fan  works harder to push the same amount of air.

Offline steve_togo

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Re: Low Air Flow
« Reply #7 on: September 20, 2018, 04:02:37 PM »
Another general question. Do you happen to know if i put an IComfort thermostat do i get all ranges of the fan speed or the same that i set via the dip switches. I have an ecobee now and I heard the Icomfort does the "Feels Like" temps. So does the fan work like a variable fan meaning does it push say from 200CFM to the max supported or does it do the same set values like i have it in my ecobee.

Offline Sergroum

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Re: Low Air Flow
« Reply #8 on: September 22, 2018, 11:47:12 AM »
No. With iComfort the cfm can change by increment of 1cfm up and down with that furnace. Not the gas valve staging though.