Two Stage Furnace and TStat SetUp
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  1. #1
    Join Date
    Oct 2006
    Location
    New England
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    13
    Thanks to the information I got from this great Forum, this past summer I made sure that my contractor installed a 2 stage thermostat to go with our new American Standard Comfort R furnace (2 stage variable speed). The thermostat is the 800 Family 7-day Digital Programmable Comfort Control(http://www.americanstandardair.com/HomeOwner/Products/Thermostats/800Family.aspx).
    The heating season has just started and every time the furnace kicks in, it goes into the high 2nd stage, which blows hard and cycles often. Since it is not particularly cold yet, this seems most unnecessary.
    I called the contractor, and he said that they usually install a single stage for this furnace and set the furnace for the 2 stages. I told him that to get the most comfort and efficiency from the furnace that the Tstat should be controlling the stages (besides the fact that the furnace clearly was set to run only on high). He said that he'll check with the tech who did the setup. He asked me if I had the manual, and I think that he wanted me to go into the Tstat install instructions and do it myself.
    Is it simple to do? I'd rather not, since I don't know what codes I may accidentily enter. However, if they don't usually use this Tstat (they had to ask the supplier which one to order) would they know how to properly set it up?

    Is it right that the Tstat should be set up to control the stages? Is it right that I should have the conractor perform this set up?





  2. #2
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,304
    I'd get them back out there and set it up right.

    There are going to be wires that needs to be remove/moved for two stage t-stat at both t-stat and furnace.


    If the t-stat is an 800, then you need to get upgraded to an 802 to get a two stage control.

  3. #3
    Join Date
    Oct 2006
    Location
    New England
    Posts
    13
    Originally posted by mayguy
    I'd get them back out there and set it up right.

    There are going to be wires that needs to be remove/moved for two stage t-stat at both t-stat and furnace.


    If the t-stat is an 800, then you need to get upgraded to an 802 to get a two stage control.
    THANKS
    Yes, it is the 802. I went into the manual and changed the codes from the factory settings for a 1 stage to the codes for a 2 stage. I performed the installation test, running the 1st and then the 2nd stage.

    Am I be ready to go now? Or do I need to have the tech change anything settings on the furnace?

  4. #4
    Join Date
    Dec 2002
    Location
    Rochester, MN
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    5,304
    We don't know if there is still a jumper on the furnace from W1 to W2 is there or not.

  5. #5
    Join Date
    Oct 2006
    Location
    New England
    Posts
    13
    Originally posted by mayguy
    We don't know if there is still a jumper on the furnace from W1 to W2 is there or not.
    Yikes. I'm not overly technical. Can you explain to me what "a jumper on the furnace from W1 to W2" is?

    Also, the first stage seems like it could be slower; the 2nd stage is almost overpowering. Can the tech change the blower speed?

    Although it is not that cold out, the furnace seems to be cycling on and off more than I would expect. I had hoped to get longer slower cycles in the 1st stage.

  6. #6
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,304
    Sorry, I can't go into details due the rules here.

    You are better off to get them back and get things fine tuned.

    Yes, the 2nd stage is going to be stronger, Was there a start up test done?

    Make sure the CPH is set at 3, it will run less on warmer days,, but when it get colder, ti will run longer. Also, this is a learning t-stat, give it a few days to to adjust.

  7. #7
    Join Date
    Oct 2006
    Location
    New England
    Posts
    13
    Originally posted by mayguy
    Sorry, I can't go into details due the rules here.

    You are better off to get them back and get things fine tuned.

    Yes, the 2nd stage is going to be stronger, Was there a start up test done?

    Make sure the CPH is set at 3, it will run less on warmer days,, but when it get colder, ti will run longer. Also, this is a learning t-stat, give it a few days to to adjust.
    Thanks, and I appreciate the rules. Not to worry, I would not touch my furnace other than to clean the filter. I asked about the W1 to W2 so I can ask the installer without sounding like an idiot - I think they already assume the worst with women.
    I know that 2nd stage will be stronger, but it seems that both stages were a bit too strong. So, was wondering if they were able to reduce the blower speed.

    I'd like to have them come out to do fine tuning, but would like to be able to clearly express to them what needs fine tuning. Especially since they seem to have little experience setting up these furnaces with 2 stage thermostats. Although they are decent size reputable company, they say that they've always installed these furnaces with single stage stats and have set the furnace for the stages. They only installed this AM STd 802 because having read this board I asked them to.
    THANKS!!!

  8. #8
    Join Date
    Oct 2006
    Location
    New England
    Posts
    13
    Okay, I found the Installer's Guide and now understand (somewhat). The furnace shows 4 wires running out to the thermostat: W1, W2, G, R (a wire is not connecting W1 to W2, if that is what "jumpering" refers to). I pulled the panel on the 802 thermostat and it has these 4 wires connected. Is this the proper wiring for the thermostat? On the forum, I've seen 5 wires referred to? (there is no cooling, humidifier, etc.)


    2nd question (2 parts), hope it doesn't get buried in the thread. A) Can the tech change the blower speeds for each stage using the dip switches and B) Is this a reasonable way to increase comfort. I ask because the heat distribution in our old house (circa 1850) is quite uneven due to duct and venting and other considerations, and I thought that if the furnace can blow slower and longer that the distribution would be improved. Although the real cold hasn't yet hit, I can tell that stage 1 blows pretty strong (as strong as the old single stage it replaced) and that the 2nd stage air flow is nearly overpowering in some rooms. Is having the tech change the flow from the factory set "normal" to medium low a reasonable way to address these concerns?

    THANKS

  9. #9
    Join Date
    Apr 2004
    Posts
    7,680
    Your furnace has an airflow requirement. In order for your furnace to run at it's optimum efficiency and reliability, there is a temperature rise range that must be maintained. Also, your duct and distribution system have ideal velocities. Lower the velocity and static too much and you loose control of the comfort.

    the efficiecy of the system will be the same from single to two stages, you are looking for optimum comfort. Really, you need your tech to come back out and verify that it is properly configured for a two individual stages. If he is reluctant, you may be simply better off to have someone else out.


  10. #10
    Join Date
    Oct 2006
    Location
    New England
    Posts
    13
    THANKS Docholiday.

    I went through the thermostat installation guide and I think that I have entered the proper codes for 2 stage set-up. Is there a test that I can run from the thermostat, that you pros will consider appropriate for the HO and not considered DIY, to test whether the set up is correct?

    Also, is the wiring that I described above correct for this equipment and thermostat? "The furnace shows 4 wires running out to the thermostat: W1, W2, G, R (a wire is not connecting W1 to W2, if that is what "jumpering" refers to). I pulled the panel on the 802 thermostat and it has these 4 wires connected. Is this the proper wiring for the thermostat? On the forum, I've seen 5 wires referred to? (there is no cooling, humidifier, etc.)"

    THANKS

  11. #11
    Join Date
    Jul 2006
    Location
    NW burbs of Detroit
    Posts
    6,058
    Originally posted by drzeuss
    THANKS Docholiday.

    I went through the thermostat installation guide and I think that I have entered the proper codes for 2 stage set-up. Is there a test that I can run from the thermostat, that you pros will consider appropriate for the HO and not considered DIY, to test whether the set up is correct?

    Also, is the wiring that I described above correct for this equipment and thermostat? "The furnace shows 4 wires running out to the thermostat: W1, W2, G, R (a wire is not connecting W1 to W2, if that is what "jumpering" refers to). I pulled the panel on the 802 thermostat and it has these 4 wires connected. Is this the proper wiring for the thermostat? On the forum, I've seen 5 wires referred to? (there is no cooling, humidifier, etc.)"

    THANKS
    Is it just me or did someone just explain the ruels of the forum?

  12. #12
    Join Date
    Oct 2006
    Location
    New England
    Posts
    13
    [/B][/QUOTE]

    Is it just me or did someone just explain the ruels of the forum? [/B][/QUOTE]

    Thanks for comments.

    hvaclover, didn't mean to run the rules. I'm just trying to educate myself (wish I had done so earlier) to make sure my set up is optimal so I can have the tech come out if need be, to make sure that me and the kids have the best heat setup before the real cold hits.

    I see that people post pics for critique. I hope it's okay to post this part of my installation for critique - the tstat wiring.

    If it's not right for running our new 2 stage variable speed furnace, then I'll have the tech out.





  13. #13
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,304
    It's wired right. I'd hook up the C for common to save on your battery, and you can also run the back light all time.

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