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  1. #1
    Join Date
    Jan 2005
    Location
    Bakersfield, CA
    Posts
    209
    Can someone take a minute and explain how a TXV and a fan delay increases SEER ratings? And what is a fan delay relay and what does it accomplish?

    Thanks

  2. #2
    Join Date
    Feb 2005
    Location
    Central Alabama
    Posts
    466
    the txv increase effiency by maintaining superheat
    under all loads , which in turn helps in maintaining the
    comfort in the home, also humidity and temperature.

    The fan delay is another question. Is it variable speed or just fan delay

  3. #3
    Join Date
    Jan 2005
    Location
    Bakersfield, CA
    Posts
    209
    I saw the reference to a fan delay on the spec sheet for a Trane XL19i AC unit. It will be used with a VS furnace.

    The Trane spec sheet (downloaded from Trane distributor) had a section that reflected EER/SEER ratings with optional equipment. The 2 options were TXV and fan delay relay.

    I've read on this post that a VS furnace or air handler will increase SEER.

    I just hadn't heard of a fan delay relay until I read it in the Trane document.

  4. #4
    Join Date
    Feb 2005
    Location
    Central Alabama
    Posts
    466
    The only way i see a fan relay helping in efficency is maybe the precooling of evaporator then the fan coming on
    only to circulate cool air and then running until all cool air is out of duct or until coil comes up to indoor temp. So they are taking more advantage of the cold coil is what i'm saying.

  5. #5
    Join Date
    Feb 2004
    Location
    mesa Az
    Posts
    15
    A txv is used to regulate your super heat, and a fan manager is going to keep your blower motor from comming on a few seconds to cool your evap coil faster. Then when your compressor shuts off the blower motor stays on for up to 90 seconds. At this time the evap coil is still cool and the air from your supply is still cool. Some techs call this free cooling.

  6. #6
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Originally posted by mrhvacman
    A txv is used to regulate your super heat, and a fan manager is going to keep your blower motor from comming on a few seconds to cool your evap coil faster. Then when your compressor shuts off the blower motor stays on for up to 90 seconds. At this time the evap coil is still cool and the air from your supply is still cool. Some techs call this free cooling.

    Exactly the "free" cooling is what raises the SEER under "test" conditions,not real conditions,in a humid climate might be best to turn it off.

  7. #7
    Join Date
    Feb 2004
    Location
    mesa Az
    Posts
    15
    A vs motor is diffrent from a fan delay.It will start out at 50% of it's rpm for aprox 3 min. Then go to 80% for the next 7 min. After that it will go 100% untill the house reaches temp. Then it will run for 3 min at 50% after the compressor has shut off. Also you will want to get the correct t-stat with a vs motor. It will make a diffrence.

  8. #8
    Join Date
    Jan 2005
    Location
    Bakersfield, CA
    Posts
    209
    Thanks for the information. I'm in a dry climate so the fan delay might be of some limited benefit.

    As usual, great responses from the professional contractors.

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