after inspection, short stage 1 cycle time before going to stage 2

Discussion in 'Maintenance and Troubleshooting' started by palandor, Jan 6, 2012.

  1. palandor

    palandor New Member

    System is a Climatemaster TT two tonne single unit with DSH and climatemaster ATP32U04 thermostat. Closed loop slinky five feet under the surface, 600 ft pipe loops for a total of 1800 ft of pipe.

    Setpoint is at 70f all the time and does not change. Outside temps are about 40-45f for the purposes of this question. Heating Algorithm is set for P&I, Anticipator is set for 3. circulating fan or set for 20 minutes on after 5 minutes without a heating call. Auxilary resistance heating coils are turned off at the breaker.

    First year, it worked great, cycled well, and used stage 1 most if not all of the time above about 25f. Heating Algorithm is for P&I.

    After the 1st year inspection this past October, with same settings (at least from what I remembered it had during the first year) it now cycles on stage 1 for 30 seconds to 5 minutes and goes to stage 2 until it satisfies the call for heating (often taking about 4-10 minutes to do so. It is then off for a 10-30 minutes until the next call for heating.
    The inspection went well and results were good and air temperature output at the furnace was 108 f with input being 70 f, although I am 95% sure that was stage 2 measurements.

    When compared to last year, post-inspection behavior seems very odd. I've checked the settings on the thermostat, tried changing Smart Recovery, Smart Heat Staging, both at the same time, etc and still get the same results of a short stage 1 cycle.
    Kilowatt usage data for November & December after the install versus after the 1yr inspection are comparable and similar enough given weather conditions, so it's not consuming a lot more energy overall, but I'd guess energy usage of the longer stage 1 run time in the first year is comparable against the energy usage of the post-inspection combined run times of a short stage 1 plus a short stage 2.

    As a new thing to try (and random info for anyone that may see something important in this info), I studied up on "Differential" vs "P&I" heating algorithms and changed the algorithm to "Differential" and set the degree differences to 1-1-2. When a call for heating is made, stage 1 now runs for about 20-40 minutes and then time off is 10-30 minutes until the next call for heating.

    I'm not sure where to start with this one. Besides calling the company/person that did the inspection, anyone have suggestions? First year stage 1 run time was really nice for air circulation in the house, plud DSH output. Is there a setting or something that got changed to make the stage 1 ontime so short before going to stage 2?

    I don't expect miracles or unreasonable results, and I'm comfortable with the fact that energy usage is about the same, but after having it work one way the first year and work differently post-inspection, my question for this thread is asking "what should I look at to get my longer stage 1 runtimes back?"
    Thanks,
    -b
     
  2. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Try to set the differential to 2-1-2. That should keep it longer in first stage. Double check the manual, since I am not too familiar with the thermostat, but I think that was the way it worked last time I touched one of these.
     
  3. palandor

    palandor New Member

    Thanks, but I'd rather not allow the temperature to drop two degrees to kick in first stage.

    My apologies if I was unclear. I am trying to figure out why, when the temperature algorithm is set to P&I, it has such a super-short first stage before kicking up to 2nd stage for a short run-time.
    I would that that it should behave the way it did first year (almost never kicking up to 2nd stage when outside temps are mildly cool (45-55).

    Is a bubble in the lines a possibility, or could something have happened when line (pressure?) readings were taken?

    Thanks,
    -b
     
  4. spf8298

    spf8298 New Member

    Did you ever get a response to your problem with your unit running short in stage 1? I'm having the same exact problems that you are having. I have 4 ton, vertical loop, Climatemaster TT27, and this is the 3rd winter I've had the unit. It has been cold here the past couple days (28 degrees F during the day and 13 degrees F at night) but for the last few months I've noticed that my unit will short stage 1 and run for expanded periods of time in stage two. AUX heat was kicking on quite often until I changed the 'smart heat staging' to a 120 minute delay yesterday, now the unit just maintains heat at stages 1 & 2.

    I can't seem to manipulate the differential settings in my thermostat (there is no setting in the menu), which is the same as your thermostat. Do you know, is there a way I can change the settings in my thermostat to allow me to manipulate the differential? I see in the manual that there is an 'installer section' that has instructions to alter settings in the thermostat, but I haven't tried that yet. Let me know your thoughts.

    Shaun Farmer
     
  5. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    why wouldn't you call the guy who inspected it and ask him if he changed anything?
     
  6. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    that would be the place to go
     
  7. palandor

    palandor New Member

    I got the differential settings to work, but found I didn't like the way it worked so I put it back to the default factory settings.
    As for the P&I short cycling to stage 2, I reset the thermostat to factory, and turned off the power for a day to it in case there was some saved setting that only reset when it was without power. It reset successfully and I had no more short cycling. I did change the sensitivity level (don't remember what the setting is actually called) so that it activates sooner when the temperature drops (or rises, in summer), rather than letting it drop more and activate later (and thus require more energy/effort to bring it back up to the set temperature).
     
    Last edited: Jan 26, 2013
    johnny1720 likes this.

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