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duct sizes

  1. ECM motor needs supply back pressure?

    I have a 4 ton heatpump. Single phase, 220v. I'm going to straight duct it into a main living area. Unrestricted return and supply, save for a filter and a few bends in some flex from the unit. Should I expect that the ECM motor (GE brand) will burn up without any restriction to air flow on...