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  1. #14
    Join Date
    Nov 2001
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    I suspect that in residential systems the coils are typically after the fans because the coil section is an add-on to the furnace. Ideally, you would stick the coils below the furnace instead of on top, but then you would have to construct the coil section to hold the weight of the entire furnace assembly. You also might have problems getting rid of the condensate if the coils were on the floor.

    You could put the coil section to the side of the furnace, and I have seen that. However, you would then have to move the filter to the inlet of the coil section and still need some elevation or a pump to handle the condensate. More floor space is needed too.

    From a manufacturer's point of view, either of these options adds cost, and this is an industry where they fight for pennies in savings. Also, draw-through could have a small negative effect on the EER/SEER based on the way those are measured.
    d

  2. #15
    Join Date
    Jan 2007
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    Mn the state where absolutey nothing is allowed
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    Quote Originally Posted by coolcoil View Post
    I suspect that in residential systems the coils are typically after the fans because the coil section is an add-on to the furnace. Ideally, you would stick the coils below the furnace instead of on top, but then you would have to construct the coil section to hold the weight of the entire furnace assembly. You also might have problems getting rid of the condensate if the coils were on the floor.

    You could put the coil section to the side of the furnace, and I have seen that. However, you would then have to move the filter to the inlet of the coil section and still need some elevation or a pump to handle the condensate. More floor space is needed too.

    From a manufacturer's point of view, either of these options adds cost, and this is an industry where they fight for pennies in savings. Also, draw-through could have a small negative effect on the EER/SEER based on the way those are measured.
    d
    i believe the reason lies in the fact the innards of a heat-x in the summer are exposed to outside air(read humid). a cooling coil before the heat-x can and will drop the heat-x below dewpoint and rot out the heat-x. the mfg would not want to warranty that

    do you really believe the manufacture cares how hard it is for you to install it?
    my boss thinks its possible to repeal the laws of physics

  3. #16
    Join Date
    Nov 2001
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    167
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    Quote Originally Posted by ch4man View Post
    i believe the reason lies in the fact the innards of a heat-x in the summer are exposed to outside air(read humid). a cooling coil before the heat-x can and will drop the heat-x below dewpoint and rot out the heat-x. the mfg would not want to warranty that

    do you really believe the manufacture cares how hard it is for you to install it?
    I don't disagree with your assessment. However, I was talking about the location of the cooling coil upstream or downstream of the fan, not the location of the HX. As noted above, the HX must always be downstream of the fan. Having the cooling coil downstream of that makes sense for manufacturing and the reason that you cited.

    Though, in rooftops the order of components in direction of airflow is almost always cooling coil -> fan -> HX.

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