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  1. #1
    Join Date
    Nov 2008
    Location
    DFW,TX
    Posts
    2,170

    Coil placement feedback; upstream vs downstream issues?

    Ok so i typically do not do many modular blower installs but have come accross afew and reading the instructions for this particualr brand it states the evaporator coil must be downstream of the blower, basically before the blower after the return. I understand we have no choice on fan coil thats the way they are built and may have something to do with water overflowing into heat strips and components, also understand same concept with upflow/vertical installs for same reason..

    However a horizontal install IMO we should have a choice and i feel we should , like a furnace install, put the coils in the upstream before the supply plenum for same reasons . I think cold air leads to moisture which also helps stick dirt and debris onto blower motor/wheel/electronics and that cannot be good.

    Why can the coil NOT be put in supply side of modular blower. Ive seem many installs way back done that way..

    so whats the theory behind the new install instructions stating to NOT install them that way now? can the blower motors not push as hard as they can pull?

    is this only for some brands?

    feedback?

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,189
    Straight cool, go for it. Keeps the mold out of the blower. Can't do it with a HP that has backup.

  3. #3
    Join Date
    Jun 2011
    Location
    Hammond,La.
    Posts
    1,176
    Good question. I have never put much thought into it but just assumed that the coils were placed at the return side to keep them from getting blasted with instant heat on electric furnaces. Will have a more gradual temperature change. Not sure what a rapid expansion of refrigerant would do to these light coils going from a winter cold evap to an almost instantly 100 something degrees blast from the heat strips.
    "I am for doing good to the poor, but I differ in opinion of the means. I think the best way of doing good to the poor, is not making them easy in poverty, but leading or driving them out of it."
    Benjamin Franklin, 1766

  4. #4
    Join Date
    Nov 2008
    Location
    DFW,TX
    Posts
    2,170
    Quote Originally Posted by BaldLoonie View Post
    Straight cool, go for it. Keeps the mold out of the blower. Can't do it with a HP that has backup.
    thats what i was thinking , good point though i guess its good to just do them the same way as maybe some of these installs could be upgraded to a HP system at a later date and having the attic equipment installed correctly the first time will save time and money in the future..

    thats good enough for me.. thanks

  5. #5
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    5,047
    Imagine that coil leaking onto your heat strips.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  6. #6
    Join Date
    Feb 2009
    Location
    Tallahassee, FL
    Posts
    6,048
    Also with the blower outlet being smaller - you wouldnt get a very uniform air flow through the coil on the supply side.

    Unless you put a nice transition and had the coil wayyy off the blower outlet. IMO

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