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Improve air flow from Coleman Blend Air small ductwork?

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  • Improve air flow from Coleman Blend Air small ductwork?

    Anyone out there have mix of regular 6" tubular ducts along with small 3 1/2" old Coleman Blend Air round ductwork? FYI the Coleman Blend Air

    Bought older house last year and learning that airflow through mix of ductwork is restricting ability of Lennox Pulse21 furnace to push enough air for A/C purposes. Heating last winter was fine, but record setting heat of 2012 was killer for system to keep up. Bad part is I've got fairly new 13 SEER Coleman 3 ton compressor outside so no real need to change out the Lennox Pulse21 furnace which is 90% and working fine (except for limited airflow).

    Any potential way for Lennox Pulse21 furnace be Upgraded with high speed variable speed blower to force more air through the whole system?

  • #2
    Re: Improve air flow from Coleman Blend Air small ductwork?

    Didnt the pulse furnace already come with a multispeed blower? It should have red, black, and white wires to the motor (heat, cool, common). What you need is a qualified heating contractor to verify the output of the furnace vs. available duct capacity. Forcing more air at a higher speed will only raise the duct pressure. It will not allow you to cool any better. You need properly sized and balanced air flow. The only reason you havent had any heating problems is that heat rises. It's easier to move warm air to the living space. it's "lighter". not technical, but you get the idea. also, the pulse has a cast iron heat exchanger. it is taking more abuse, in your setup, where a normal pressed steel exchanger would have burned out long ago.

    your best option would be to change out the undersized ducts with ones equal to the others.

    ... it was plumbed by Ray Charles and his helper Stevie Wonder