Page 1 of 7 1234567 LastLast
Results 1 to 13 of 87
  1. #1
    Join Date
    Jun 2006
    Posts
    110
    Trying to set up new furance (Bryant Evolution Plus90I, variable speed, 2 stages).

    Using a Honewell FocusProTH611)D.

    Setup of stat has "Heating cycle rate" setting.

    Please explain what this is for. What is "cycles/hour"? What is considered a "cycle"?

  2. #2
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,304
    Cycle is run per hour on an AVG.

    If you set it to 3, it will run avg of 3 times in an hour.

  3. #3
    Join Date
    Jun 2006
    Posts
    110
    Is this something to be changing? Is it something one adjusts, or is it dependent on the furnace/system type?

  4. #4
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,304
    Most of the time out of the box it's set at 5, in the owners manual says what system for CPH. Lot of us here agree 3 on all system. 5 is too much (Short cycle) where 3 is right. less stop and go.

  5. #5
    Join Date
    Jun 2006
    Posts
    110
    So a problem I had observed from the beginning with the new furnace system was that seemingly without regard to there being no differential between actual temperature and setpoint the system would kick into High Speed heat mode approximately 3 times/hour. The heating cycle rate on the stat was set to "3" as per the recomendation in the installation manual (stating 3 was for furnaces over 90% efficiency). The system had been sold to me as one which would be silently and gently maintaining temperature on Low Speed mode (which truly is very silent, very nice).

    After much back-and-forth with the contractor, they sent out their technician to look. He agreed that it didn't seem to be working as one would expect, but didn't really seem to know why.

    So, he set the stat Heating cycle rate to 6 (indicating that this was what they normally ran their systems at) and told me to see what it would do.

    It seems to have worked, the system now only kicks into High Speed in the mornings when bringing the house up to temperature. However, I really don't know how often it is cycling to "heat" mode because it is so silent in Low Speed.

    So then now I'm concerned as to whether the system is actually set up correctly or is it now set up incorrectly in order to get required results, but in the end will harm my investment.

    I.E. why should I care if it is set to 1,2,3,4,5,6,...?
    and why is "3" the recommended setting for high efficiency gas furnaces?

  6. #6
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,304
    Yikes 6 on a 90% system!?

    man, that will be hard on the system cycling on and off often about 6 times an hour.

    They make sure the 1st and 2nd stage wire wasn't turned around or something?

    I would try to reset the t-stat, and start over. if everything is wired right... If that don't work. maybe a defect?

    if the system is set at 6, the run time is too short, and not going to get your full efficiency.. It takes the system about 10 min to get at it's peek efficiency as everything warms up.

    Now the longer run cycle you can get out of it, the better efficiency you can get out of it.. Like in your car, you going to get better gas milage on cruise or stop and go?

  7. #7
    Join Date
    Jun 2006
    Posts
    110
    That's what I had surmised to this point (that 6 isn't advisable).

    So I'm totaly unclear on how the stat determines when to cycle. How does the stat determine when to turn on and off (other than if there is a temperature differential?

    Perhaps I should state the problem/concern that has lead to this question: The problem is the furnace keeps kicking into High Speed operation when it is supposed to be cruising along only in Low Speed (High Speed being only for making up large temperature differentials such as during recovery in the morning). I'm getting about 3 cycles of Low-then-High speed operation each hour.

    Basic logic (which so far has always failed me in these HVAC discussions) tells me that if the stat is going to cycle 3 times/hour then this means it must somehow be breaking the hour down into 20 minute segments and then running the heat for a period of time in each segment. If cycle is 6 it breaks it into 10 minute segments and runs for a while each segment (at Low Speed). So what determines how long it runs in each segment of time?

    Where am I going with this? The manual on the Bryant furnace (a 94% furnace) indicates that it will switch to 2nd stage (High Speed) after 16 minutes of 1st stage operation. I am again making an assumption that this means if the furnace turns on at Low Speed, then if it is still running after 16 minutes it will kick into High Speed and run for some amount of time (how long?). So then this would/could explain why when set to cycle rate of 3 the High Speed always kicks in, because to get only 3 cycles/hour means that Low Speed runs longer...perhaps all the way out to 16 minutes which automatically triggers the furnace to kick into High Speed.

    Setting the cycle rate to 6 causes the furnace to run short (and inefficient) bursts of Low Speed, much less than 16 minutes and therefore High Speed never kicks in.

    Is this close?

    Why am I not dealing with the contractor on this? Because I'm not confident of the answers I'm getting. It seems that no matter what I ask the answer is always "that's the way it is supposed to work" even if it starts working totally differently the answer is then still "that's the way it is supposed to work". I have every expectation that the contractor is going to answer my question as to why I have to run 6 cycles/hour with "who cares, that's how it is working so just leave it that way".

  8. #8
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,304

    Found your problem.

    I went back to the start of your post and saw that you said you have FocusPro 6110


    Found your problem!

    That t-sat is an SINGLE stage t-stat, NOT a two stage t-stat.

    The 16 min timing is used on single stage, if two stage t-stat (TH6220) is used, the timer is taken out of the picture.

    so, maybe that's why the set it at 6 CPH to advoid people complaning about system running high fire for a few min.

  9. #9
    So, I don't intend to hi-jack this post by any means but I do have a follow-up question re: CPH settings. I have a dual-fuel system with a single-stage HP and a two-stage 80% variable speed gas furnace. A Honeywell VisionPro IAQ T-stat is running the show. Actually, my wife runs the show, but ah, nevermind. I digress...

    I notice in the installer settings for the T-stat the following:

    Code 172 (System Selection) - 2 (Heat Pump)
    Code 174 (Number of Cool/Compressor Stages) - 1
    Code 176 (Number of Conventional Heat or Heat Pump Aux Stages) - 2
    Code 220 (CPH for 1st Stage Cool/Compressor) - 3 (CPH recommended for compressors)
    Code 240 (CPH for 1st Stage Conventional Heat or Auxiliary) - 5 (5 CPH used for standard fossil fuel forced air (less than 80% efficient) systems)*
    Code 250 (CPH for 2nd Stage Conventional Heat or 2nd Stage Auxiliary) - 5 (5 CPH used for standard fuel forced air (less than 90% efficient) systems)

    So, if I understand this correctly, my heat pump is set for 3 cycles per hour which sounds right in order to maximize comfort and efficiency. However, both stages of the gas furnace are set to 5 CPH. *Note, that for installer code 240 it references 5 CPH as the setting for 1st stage gas furnaces less than 80% efficienty. 3 CPH is recommend for 1st stage gas furnaces 90% or better efficiency. So, since my gas furnace is rated, or marketed as 80% efficient, is 5 CPH the correct setting, or should it be 4?

    The description is different for the recommendations for the CPH settings for 2nd stage. 5 CPH is recommended for furnaces less than 90% efficiency. 3 CPH is recommended for for 2nd stage furnaces 90% or better efficiency. Again, is 4 CPH the "more correct" setting?

    Do these "recommended settings" take into account whether your furnace is running a variable speed fan? If my goal is to maximize comfort, efficiency, and durability of my system are these current settings the appropriate ones? What's the impact if I choose to lower the gas (1st and 2nd-stage settings) to 4 or 3 with an 80% efficient furnace? Or, if there are concerns re: DIY guidance, what if I ask my contractor to come out and change these settings to something lower?

    Thanks for your time.


  10. #10
    Join Date
    Dec 2004
    Location
    Derby City
    Posts
    3,963
    To the original poster and the hijacker: Uh, yeah, call out the original contractor with whom you invested $$$ for this system. You should not be trying to straighten out a system that you bought and had installed from a legit contractor. If you don't get satisfaction for whatever reason, call the local Bryant office. They will do "whatever it takes." I repeat, call a contractor. Here you are trying to straighten out a problem with the system and it turns out to be the thermostat!!?? And, we're here and you're there..........

    I don't understand why individuals will come here and post a question after they have invested hundreds and thousands of dollars with a contractor, but they won't ask the same question of that contractor. What's up with that?
    Everyone has a purpose in life..........even if it's to be a bad example.

    Seek first to understand, before seeking to be understood.

  11. #11
    Join Date
    Dec 2004
    Location
    Derby City
    Posts
    3,963
    To the original poster and the hijacker: Uh, yeah, call out the original contractor with whom you invested $$$ for this system. You should not be trying to straighten out a system that you bought and had installed from a legit contractor. If you don't get satisfaction for whatever reason, call the local Bryant office. They will do "whatever it takes." I repeat, call a contractor. Here you are trying to straighten out a problem with the system and it turns out to be the thermostat!!?? And, we're here and you're there..........

    I don't understand why individuals will come here and post a question after they have invested hundreds and thousands of dollars with a contractor, but they won't ask the same question of that contractor. What's up with that? All the best, John.
    Everyone has a purpose in life..........even if it's to be a bad example.

    Seek first to understand, before seeking to be understood.

  12. #12
    Hey, John.

    Thanks for the reply. I fully understand the jist of your message. I have worked closely with the contractor for several weeks "fine-tuning" my install that I did pay lots of $'s for. The reason I have the VisioPro IAQ T-stat is because I'm the one that requested a change-out from the originally installed Lenox T-stat.

    I'm just trying to better understand myself how to optimize the overall peformance and longevity of my system. Like others, this forum has provided lots of great information for me so I could competently communicate with my contractor re: desired equipment and configuraiton options. I have asked my contractor many of these same questions and look to you and other professionals to validate the information I'm provided.

    Thanks again for your assistance, and apologies to the original poster for derailing this conversation.

  13. #13
    Join Date
    Dec 2004
    Location
    Derby City
    Posts
    3,963
    Kinda off the subject, but one of these days, contractors are gonna start asking their customers,

    "You've been on that hvac-talk site haven't you?"

    Then they look at your with one raised eyebrow.

    We love giving out advice. And, we're arrogant to boot!

    But there will never be a substitute for someone who has first-hand familiarity with a system versus us who are working 'sight unseen.'

    You will never find a non-willingness to help from anyone here at this site, BUT, you also won't find anyone who will try to guide someone through something that may hurt person or property regardless of the best intentions.

    All the best, John.
    Everyone has a purpose in life..........even if it's to be a bad example.

    Seek first to understand, before seeking to be understood.

Page 1 of 7 1234567 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event