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  1. #1
    My buddy recently installed a Trane XL90, two stage furnace and is happy with it. I was set to go with that, but the sales people almost have me convinced that the Trane variable speed XV90 is much better. I'd appreciate your opinion, especially if you service these furnaces.

  2. #2
    Join Date
    Jan 2005
    Posts
    95
    Muddled,go with the variable speed furnace its worth the extra cash,especially during cooling.

  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,398
    The variable speed is nice if budget allows and installers are smart enough to set up properly. If in a humid climate, add a humidistat for dehumidify on demand capability or get it as part of your thermostat.

    Buy an extended warranty, parts is pricey if something fails!

  4. #4
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,852
    Variable speed is the way to go for best ability to regulate comfort in heating or in cooling. Just don't restrict the air with a variable speed blower.
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  5. #5
    Join Date
    Jan 2005
    Location
    Dallas, TX
    Posts
    154
    Originally posted by RoBoTeq
    Variable speed is the way to go for best ability to regulate comfort in heating or in cooling. Just don't restrict the air with a variable speed blower.
    What do you mean by your second sentence??

  6. #6
    Join Date
    Apr 2004
    Location
    Niantic, Illinois
    Posts
    545
    Basicly, the installing company needs to look at the ductwork to determine that it will handle the airflow required for the new system. If the duct is to small it will be a furnace killer.

  7. #7
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,304
    I have the XV90 in our house and love it.. The quiet air flow when the fan is "ON" all times. and even temp in heating..

    Agree with the other guys. make sure the duct is sized right to handel it.

    I got the 10 years warranity, and will be worth it in the long run if something did go wrong.

    Also with the Variable speed, it use less power. And make sure you get a 2-stage t-stat. Don't fall for the dealer saying the timer will work just as well.

  8. #8
    Join Date
    Jan 2005
    Location
    Bakersfield, CA
    Posts
    209
    Could someone give the consumer a brief primer on fans? Baby b said the VS furnace would be of great benefit for cooling.

    Here's a real HVAC 101 question from an accountant:

    What does the VS fan on the furnace have to do with the fan or delivery system of the AC of a split system? Does having a VS furnace mean that you have a VS AC as well?


  9. #9
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,803
    Originally posted by nathan9999

    What does the VS fan on the furnace have to do with the fan or delivery system of the AC of a split system? Does having a VS furnace mean that you have a VS AC as well?

    If you have a VS blower on the furnace, you have a VS blower for your a/c, it gives good humidity control, allows better control of cfm for both heating and cooling, and uses less electric to deliver the conditioned air.

    Putting a VS blower on bad duct work, doesn't make it good duct work. If you restrict air to a vs, it will have a shorter life span, and can get loud.
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  10. #10
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,398
    Some brands have a feature where the variable speed blower slowly ramps up in cooling mode. This allows the coil to get cold fast and really increases moisture removal. As far as I know, about all of them have the capability for dehumidification on demand where the blower slows 10-15% if humidity is high. This requires a simple humidifier-type humidistat wired on or a thermostat with this capability.

    Without the ramp up or humidistat, the variable speed blower wouldn't have any special cooling capability.

  11. #11
    Join Date
    Apr 2005
    Location
    illinois
    Posts
    257

    vs and zoning

    From the prior comments on vs and inadequate ducts it would seem tha vs and zoning may not work well. That is to say when only one of multiple zones calls the ductwork has to be undersized. Prior posts have also said a bypass damper should be avoided if possible with zoning. What do you think of zoning and vs where you are retrofitting?

  12. #12
    Join Date
    Apr 2004
    Location
    Niantic, Illinois
    Posts
    545
    It works fine as long as your zones aren't way out of proportion with one another.Aslo the vs units are two stage which is a huge help in zoning. Here is an example: You have a 90,000 btu/h of output on your furnace. Your first zone needs about 75,000 of this and your second needs about 15,000 of this. When the small zone calls it will be getting way to much production from the furnace, over heating and limiting. No amount of by-pass will help this imbalance and even a two stage of vs unit will have a tough time delivering proper heat to that zone. You would have to choose between over conditioning the zone or beating your furnace to death. If you arrange the duct system to make for a more equal split of the zones you can set up a two stage or vs to operate on low-fire while one zone calls and high fire when bothe stages call. With the right by-pass and duct sizing you will be very pleased.

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