I have a Goodman 40,000 Btu 96% ecm motor furnace ready to install. When I ordered the furnace I checked the spec sheet. The furnace I received had completely different specs. Every airflow value on the table was multiplied by exactly 1.96 but the temperatures were unchanged. I have degrees in physics and engineering, so I know this is not possible.
For example the old spec sheet shows a 61F degree change with an airflow of 581 cfm. The update sheet shows a 61F degree change with an air flow of 1139 cfm
The old and new spec sheets still show the same temperature rise range of 35 - 65 in degrees F. Also the same output BTUs
All of the other size furnaces have values that are unchanged from the old to new spec sheets.
I checked the values with equation (output Btu)/((change in temp)x(1.08))=(airflow in cfm). All of the other sizes of furnaces give the right values but for the 40,000 Btu furnace the values are off by a factor of 1.96. The same errors are on spec sheets for both the upflow and downflow.
The distributer said "specs change thats just the way it is." I could understand 20% but not 200%.
I know that ecm motors don't like pushing against a high static pressure. I don't think most systems could handle a doubling of airflow.
Goodman tech support said something seems off. They left a message with the Product Specialist, but no one has called me back.
I know Goodman must have made a production error. I am sending the furnace back.
How come Goodman isn't flooded with calls from distributers and techs? Don't most installers read the manuals? Don't most installers notice when the Temperature rise is half of what it is supposed to be?
Any suggestions or questions would be appreciated.
Thanks Eric
For example the old spec sheet shows a 61F degree change with an airflow of 581 cfm. The update sheet shows a 61F degree change with an air flow of 1139 cfm
The old and new spec sheets still show the same temperature rise range of 35 - 65 in degrees F. Also the same output BTUs
All of the other size furnaces have values that are unchanged from the old to new spec sheets.
I checked the values with equation (output Btu)/((change in temp)x(1.08))=(airflow in cfm). All of the other sizes of furnaces give the right values but for the 40,000 Btu furnace the values are off by a factor of 1.96. The same errors are on spec sheets for both the upflow and downflow.
The distributer said "specs change thats just the way it is." I could understand 20% but not 200%.
I know that ecm motors don't like pushing against a high static pressure. I don't think most systems could handle a doubling of airflow.
Goodman tech support said something seems off. They left a message with the Product Specialist, but no one has called me back.
I know Goodman must have made a production error. I am sending the furnace back.
How come Goodman isn't flooded with calls from distributers and techs? Don't most installers read the manuals? Don't most installers notice when the Temperature rise is half of what it is supposed to be?
Any suggestions or questions would be appreciated.
Thanks Eric
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