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  1. #1
    Join Date
    Aug 2005
    Posts
    93
    Hit minus 7 this morning at 6 am (windchill -27!!!). So much for minus 4 design day for northern Illinois (between chicago/wisconsin)

    Summary of my situation....

    Old furnace system was 80K BTUH Bryant Single stage unit.

    Home size - first floor about 1350 SF, finished basement about 1000 SF. 1964 home. Did not heat/cool finished basement before.

    New system is 80K BTUH Carrier Infinity System. Added Ducts to heat/cool finished basement.

    Calcs showed a load of about 70,000 BTUH using first floor + basement + future 400 SF addition. Winter Design day temp of minus 4 used.

    Watched the infinity controller for a short time. Never saw it go to high stage heat but it did stay on low heat – heating nearly all the time (50 mins/ hour) this morning.

    Good thing I did not listen to the other bidders who wanted to sell me a 100k BTUH system. Their Logic = you had 80K + small future addition = 100K.

    It appears to me I could have gone with a 60k furnace since it never went to high heat this morning - but perhaps a 60K unit would bee a tad short when I put on the family room addition next year. Glad I went with a two-stage burner and VS fan system in any case.

    Should be interesting to see summer operation with new AC unit, which is also the infinity two-stage type.

  2. #2
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,305
    Sounds like it's working right.

    Where are you out of?

    Minnesota here, and I had -18 this morning, and furnace is running in 2nd stage for about 15 min, then 1st stage for about 20 min.

    I couldn't imagin having a 2 stage on a timer.

  3. #3
    Join Date
    Aug 2005
    Posts
    93
    Thanks - I am in a small town about 35 miles north of Chicago, IL along lake Michigan.

    I think it is working about right too - given that I need a little reserve capacity for my addition.

    The infinity controller is nice - I just watched the clock to see how long it went into heating mode (watching wether it was low or high). It was into low heating about 50 mins. Then off for 15 mins or so - then back on. Not really a timer - the controller determined how long to be on.


  4. #4
    Join Date
    Feb 2006
    Location
    Horicon, Madison, Milwuakee WI
    Posts
    32
    Carriers two stage Furnaces will run 10 or 15min on first stage if T-stat is not satisfied in this time it should go in two second satage which pumps more gas in to the burners and ramps up rpm's on the blower if your ran 50 min on first stage it is not properly hooked up it has nothing to do with the btu it puts out or the requiered btu for your home. The purpose of matching you Btu demand and you furnace is so that you don't end up with a unit that runs all day and it's always cold or a unit that runs 5 min and kicks out on high limit. I can only think of three reasons why it didn't kick in to second stage either there might be t-stat setting preventing which is unlikly or the t-stat wiring its missing a jumper from 1st stage to 2nd stage or the gas pressure setting on first and second stages were never properly set but the fan would still go in to a faster rpm's so have your contractor watch it run for longer than 15 min and see what he says is not kicking in second satage.

  5. #5
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,795
    2 stage furnaces shouldn't go to second stage after x minutes, the stat should determine when it goes to second stage.

    His Infinity controler is controlling the staging, not the furnace timer.
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  6. #6
    Join Date
    Aug 2005
    Posts
    93
    hmmmm... conflicting professional opinoins. Now I am wondering.

    Isn’t Dash here on this board the resident Carrier Pro?

  7. #7
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,795
    There's several Carrier guys here, including a tech rep, one of them should see this thread soon.

    Your controller is doing what it is suppose to do.
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  8. #8
    Join Date
    Feb 2006
    Location
    Horicon, Madison, Milwuakee WI
    Posts
    32
    I've installed plenty of carriers the t-stat conectiones have w1 and w2 jumpered the furnace goes on to second stage after x min if you don't have the jumper and you have a special t-stat then the setting on your t-stat or zone controler would power up the w2 terminal I'll have two look up my manuals.

  9. #9
    Join Date
    Feb 2006
    Location
    Horicon, Madison, Milwuakee WI
    Posts
    32
    with infinity control you might have a set up that compares the outside temp and the temp your are at and the temp you are requiring and the control system it self would decide if its required to go two second stage but there is no reason why you should have to wait 50 min in low stage for your t-stat to be satisfied if thats the case your control should of kicked on second stage right away.

  10. #10
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,795
    The long run time in first stage is for comfort.

    When its real cold out, it keeps a nice even temp in the house, and eliminates cold drafts.
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  11. #11
    Join Date
    Feb 2006
    Location
    Horicon, Madison, Milwuakee WI
    Posts
    32
    Ok! Sorry what I meant was 2 stage furnaces with regular t-stat will kick in to 2nd stage in a x amount of time if wired properly. Now the infinity control will take multiple in-puts such as outside temp, inside temp, desired temp, an posibly even last time it was cicled on or running and then determine if seconed stage is needed I still do not think you should have to wait almost an hour for your furnace to satisfy your t-stat. is this system zoned or not?

    [Edited by vics_zone on 02-22-2006 at 08:03 PM]

  12. #12
    Join Date
    Aug 2005
    Posts
    93
    No the system is not zoned.

    In general the infinity controller did a good job of maintaining an even temp in the home.

    I have the system set up to maintain and average temp of 70 degree in my old home, but a few parts of the home vary up to 2-3 degrees.

    I would say that during the off time (the 15 mins) the temp dropped 2 degrees below 70 in most parts of home, then the system kicked on an maintained the temps back again to mostly 70. However, I only watched the system for about 1.5 hours.


    Bottom line is that I was comfortable, just wanted to see if the system would ever kick into high heat, which it did not. I suppose it is desirable for a nice long low heat/low fan cycle, rather than shorter high blasts (like my old single stage Bryant system did last year).

    I read somewhere that the VS two stage system is supposed to be in low mode like 90% of time if properly sized... and as mentioned I am a bit oversized, so perhaps even at - 7 degrees, low heat is enough. I see the low heat mode for my unit is 49K BTUH out of 75K available.

    Not an expert though... appreciate all of your comments.


  13. #13
    Join Date
    Feb 2006
    Location
    Horicon, Madison, Milwuakee WI
    Posts
    32
    yeah! ok I was under the impresion that the unit ran that long and just never really warmed up. everything you said sounds right I would have to say that if you want it to kick into second stage just to see if it works, try this!on a cold day with your setback thermostat let it drop lets say to 60 degrees while your at work when you come home set it to your normal setting of 70 degrees, and maybe taking in consideration its 30degrees or less outside and the furnace now has to make up 10+ degrees maybe that will triger the system to go into second stage. and good luck and sorry i got your thread so out of track. I my self fond of carrier systems and just did not realize you had the infinity control instaled thus I thought they were for zoned systems only.

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