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  1. #1
    Join Date
    Jan 2002
    Posts
    57
    They have finally completed intallation of my zoned HP system. It's been running about a month, but it does not seem to operate as I might expect. Here's the specs:

    Am. Stnd. 5 ton HP with dual fuel and two compressors. This is their 19 SEER unit. Variable speed Am Stnd. air handler. Honeywell 4 zone contol system with two zones being utilized. The two stats are Honeywell programable and have the hold button on the front.

    We are still finishing up the home so we have not yet moved in. I have reset the stat schedule so that every time period the heat is set on 60. The stat always shows the room temp is 60.

    I don't understand why the stat triggers the unit to come on even when the room temp does not change. It's almost like it's on some kind of timer. The stat makes a "click", the unit comes on, runs for a short period maybe 2 or 3 minutes then it purges and shuts off. The same routine begins again a few minutes later, the room temp has never changed.

    I don't know why it does this? Shouldn't the stat show a reading of 59 degress before the unit kicks on? I had hoped getting the high efficiency HP would be benifical, but I don't imagine I'm get much efficiency with such short cycling.

    Any thoughts before I call them back for a second look?

  2. #2
    Join Date
    Mar 2001
    Posts
    285

    Don't expect it to turn on at 59.0 then shut off at 61.0*. It's probably keeping the room 60.2*-60.8*.

    2-3 minutes sounds like an awfully short run-time for a heatpump... was a heat load study done? Are you sure the heatpump has clicked on an off within those two to three minutes? It can take a couple mintues before heatpumps start warming....what temp is it outside and what temp do will you keep it when the house is occupied?

  3. #3
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,641
    see if cycle rate is adjustable. most digital stats will cycle close enough that you will never see temp change on display.

  4. #4
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,750
    As stated above, check the CPH setting. If its at 6, change it to 3.

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    How many times must one fix something before it is fixed?

  5. #5
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,376
    Some stats will show a change, others won't. Usually Honeywell & W-R don't show a 1 degree change, Robertshaw & Totaline do. How is the staging done? By the zone panel?

  6. #6
    Join Date
    Jan 2002
    Posts
    57
    A heat load was done. As a matter of fact due to this forum I went through "a number" of different contractors before settling on this one for the install, mainly because he actually goes by a heat load rather than a rule of thumb. Which most in this area do. I also purchased HVAC Calc and ran my own load to confirm what he did.

    The short run time is what bothers me. In my current home, the one we will be moving from, the unit runs much less and I know the new house is much better insulated and sealed.

    The setup was explained to me this way: Once the stat calls for heat (or cool) the HP starts up and runs the smaller compressor trying to meet the demand, if it cannot meet the demand within a certain time period (I have forgotten what he told me that was) then the smaller compressor shuts down and the larger one kicks in. If the demand request is more than a few degress the compressors don't run but rather the gas burner kicks in and boosts the heat then the compressor takes over.

    The outside temp here lately has been in the upper 40s and sometimes higher. There is supposed to be a sensor on the unit outside that determines the outside temp. so that the HP does not run below a certain temp., causing a switch over to the gas unit.

    I know there are a number of dip switches he adjusted to control time and so forth, and at this point I'm not really into adjusting those, but rather more interested in how it should work and what questions I should ask when the tech. comes back out. It's my understanding that the staging is done on the Honeywell zoning board.

    I guess my preference would be to see a temp drop on the stat before anything turns on, (maybe not realistic) and for the unit to run a while before shutting down. This on off business is bound to keep the efficiency rating way down.

    I relly don't know yet how things are going to work once occupied, since we're still under contruction. I do know we set the temp up to 72* while the floors were being finished, but at the time the outside unit was missing some kind of sensor so the tech. set the unit to only run on the gas. The compressors never ran, but the gas unit did exactly what the HP is doing now, on and off every few minutes. And boy was my gas bill high! (It was much colder outside during this time than it is now.)

    thanks for your help

  7. #7
    Join Date
    Jun 2001
    Location
    Louisville, KY
    Posts
    12,000
    As stated, you won't see a drop in displayed temperature. The 3 minute run time is minimum that it will run. With the rather cool indoor temp and mild outdoor temp, there's not much load on the system. So, the resultant run time will be short. Do have the cycle rate checked. It should be moved to 3.

  8. #8
    Join Date
    Apr 2005
    Location
    Kingston Ontario Canada
    Posts
    1,209
    Originally posted by dogbone
    A heat load was done. As a matter of fact due to this forum I went through "a number" of different contractors before settling on this one for the install, mainly because he actually goes by a heat load rather than a rule of thumb. Which most in this area do. I also purchased HVAC Calc and ran my own load to confirm what he did.

    The short run time is what bothers me. In my current home, the one we will be moving from, the unit runs much less and I know the new house is much better insulated and sealed.

    The setup was explained to me this way: Once the stat calls for heat (or cool) the HP starts up and runs the smaller compressor trying to meet the demand, if it cannot meet the demand within a certain time period (I have forgotten what he told me that was) then the smaller compressor shuts down and the larger one kicks in. If the demand request is more than a few degress the compressors don't run but rather the gas burner kicks in and boosts the heat then the compressor takes over.

    The outside temp here lately has been in the upper 40s and sometimes higher. There is supposed to be a sensor on the unit outside that determines the outside temp. so that the HP does not run below a certain temp., causing a switch over to the gas unit.

    I know there are a number of dip switches he adjusted to control time and so forth, and at this point I'm not really into adjusting those, but rather more interested in how it should work and what questions I should ask when the tech. comes back out. It's my understanding that the staging is done on the Honeywell zoning board.

    I guess my preference would be to see a temp drop on the stat before anything turns on, (maybe not realistic) and for the unit to run a while before shutting down. This on off business is bound to keep the efficiency rating way down.

    I relly don't know yet how things are going to work once occupied, since we're still under contruction. I do know we set the temp up to 72* while the floors were being finished, but at the time the outside unit was missing some kind of sensor so the tech. set the unit to only run on the gas. The compressors never ran, but the gas unit did exactly what the HP is doing now, on and off every few minutes. And boy was my gas bill high! (It was much colder outside during this time than it is now.)

    thanks for your help
    Any piece of heating or cooling equipment is oversized when the outdoor temperature is above design temperature! So with a indoor temperature of only 60 degrees and the outdoor temprature temperature in the high 40's and above the equipment is going to short cycle. I have a Carrier digital thermidistat and i found that is was too sensitive to temperature swings, too. It seemed anytime you walked by it, it would click on the heatpump. Mine has an adjustable anticipator, so I adjusted it to the hightest number I could. It has helped, some. I also plugged the hole where the wires of the thermiistat came thought the wall, which wasn't done on install. This helped some, too.

    Thorton

    [Edited by thorton on 02-01-2006 at 11:57 AM]

  9. #9
    Join Date
    Jan 2002
    Posts
    57
    where would the cycle rate adjustment be located. I looked on the digital stat and there are not switches to be seen even after taking it apart. Is there a software switch?

    Or is this done on the zoning board?

    thanks

  10. #10
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,376
    Whose zone panel? I like the TZ4. You can have it stage by % of zones calling so if you have 1 zone on, it won't run 2nd stage. Only if most of the zones need comfort does it switch to high. I set up a friend's that way. It takes all 3 zones to bring on high fire with the gas backup. That would be rare.

    Most HW stats have adjustments in the advanced setup for cycle rate.

  11. #11
    Join Date
    Jan 2002
    Posts
    57
    Total zone 4 I think is the name on the box. It's Honeywell. We're only using 2 zones.

  12. #12
    Join Date
    Nov 2003
    Location
    Olympia, WA
    Posts
    47
    Its been a little while since I've done one of these two stage dual fuel set ups with a zoning system.

    There are a few models of thremostats which have a cycle per hour function. Would you beable to tell us what the model number is?

    As for the dip switches for your application.. from left to right
    ---Dips 4 (using 1stage heat/cool Tstats)---
    down/up/down/down/down/down/down/down

    ---Dips 4 (using 2stage heat/cool Tstats)---
    up/up/down/down/down/down/down/down

    ---Dips 5---
    down/up/down/down/up/up/up/down
    *note: Switch number 2 is used for your lowest cooling supply temperature. Up is 40F Down is 48F I'm used to a setting of 45F to prevent evaporator coil freeze ups.

  13. #13
    Join Date
    Jan 2004
    Posts
    60
    Originally posted by BaldLoonie
    Whose zone panel? I like the TZ4. You can have it stage by % of zones calling so if you have 1 zone on, it won't run 2nd stage. Only if most of the zones need comfort does it switch to high. I set up a friend's that way. It takes all 3 zones to bring on high fire with the gas backup. That would be rare.
    Are you talking about 50% rule?

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