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  1. #1
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    HEATPIPS in FAHU

    The FAHU that is around above 200-ton capacity with 4 number consist heat recovery and heat pipe. We face a problem that ahu room where no space to remove the giant heat pipe to service and the 6-row cooling coil which trapped inside the heat pipe. The ahu is working without service the cooling coil from last 10 year. Some people opined that eliminate the heat pipe, because already system has heat recovery. heat pipe only will slightly maintain RH and it is trivial. And will get more space to service the cooling coil. What are your comments. Thanks
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  2. #2
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    Well i cant say i really understand your situation but i am certainly interested.
    What does the heat pipe do? Is it setup to help control humidity by bypassing sensible heat around the coil? If so than it seems from my research that you would be marginally increasing the system sensible capacity while decreasing the latent capacity if you remove it.
    I would start by asking my self if i can afford the reduction in latent capacity.
    Also will the increased sensible capacity cause short cycling or worsen it?
    Was it installed because of a specific need for it or was it just a salesman making more profit on unnecessary add-ons?

    I have to say that you always have the most interesting questions.

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  3. #3
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    This is a combination of pre cool and reheat process by which change the saturated condition of air off temperature. RH will only be varied by this arrangement.
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  4. #4
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    Exactly just a different way of saying it. You're basically taking sensible heat and bypassing it around the coil. So that the coil can remove more moisture.

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  5. #5
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    I put the manufacture’s documented typical design value in psychrometric then I found only a very little arounf 0.91lb(w)/lb moisture content (absolute humidity) removed by the pre cool coil. but the RH maintains 60% after the reheat coil.
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  6. #6
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    We are in a very humid area that is also hot in the summer.
    I have seen "0" heat pipes here. Now my brother is in a cooler climate and puts them in regularly.
    IMHO they seem to be one step above snake oil... Not worth the (install) money or aggravation.
    Life is too short, Behappy!
    TFMM

  7. #7
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    Thread Starter
    Quote Originally Posted by behappy View Post
    We are in a very humid area that is also hot in the summer.
    I have seen "0" heat pipes here. Now my brother is in a cooler climate and puts them in regularly.
    IMHO they seem to be one step above snake oil... Not worth the (install) money or aggravation.
    I align with you, after the psychometric analysis, i thing there is not much benefit from heat pipe. really welcome if any different comments and more lights to the subjects

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  9. #8
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    Keep us posted.
    If you do remove it i would love to see before and after refrigerant saturation temps and dew points of supply and return air.

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  10. #9
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    Interested in this. Wouldn't the benefit be the energy saving from the easier cooling and moisture removal by the cooling coil? I see the "free" reheat temperature rise after the coil and think less natural gas or electric reheat.

    You are transfering the energy you want around the cooling coil instead of making the cooling coil remove this energy, then adding energy after coil?

  11. #10
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    It seems like a desuperheater type setup would be more efficient than the heat pipe anyway because it could help lower head pressure.

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