Results 1 to 12 of 12

Thread: Goodman mod

  1. #1
    Join Date
    Sep 2002
    Location
    I don't know
    Posts
    2,909

    Goodman mod

    How is the GMVM96 controlled?

    Does it modulate with a 2-stage t-stat or only with the communicating t-stat?

    What kind of algorithm does it use to control output without the communicating stat?
    General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"

  2. #2
    Join Date
    Dec 2006
    Location
    toronto, canada
    Posts
    551
    If use single or two stage tstat, just like lennox SLP. If use their CTK2A T-STAT, it's full modulating. I believe the CTK2A is same as Rheem's series communicating modulating tstat.

  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,594
    With a 2 stage stat, will it modulate to a lower rate if 2nd stage is satisfied or does it stay high like a Lennox?

    And with the communicating stat, it modulates based on house needs like a Rheem?

  4. #4
    Join Date
    Sep 2002
    Location
    I don't know
    Posts
    2,909
    I just read the install manual - it works like the lennox.

    Low is 50%, not 40% like the others.

    Not sure how it works with the communicating t-stat, but I doubt it drops down.
    General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"

  5. #5
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,594
    So even though the stat says less heat is needed, it keeps blasting. So much for long run cycles on gentle, quiet low

  6. #6
    Join Date
    Sep 2002
    Location
    I don't know
    Posts
    2,909
    Perhaps the manufacturers do it to avoid complaints - many people still think furnaces are supposed to cycle a lot.

    Manufacturers give the distributors and dealers what they want I suppose; after all, we have 2-stage units which work on timers and the option of using indoor air for combustion.
    General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"

  7. #7
    Join Date
    Sep 2002
    Location
    I don't know
    Posts
    2,909
    There actually is a mod communicating stat available...
    Attached Images Attached Images
    General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"

  8. #8
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,763
    Amd, that PDF is very unclear to me. Anybody else make heads or tails of it?

    Seems goodman doesn't quite understand the point of modulating OR communicating...

    Just tell the system how far away it is and let it try to keep temp tight and match loss! Why do they want it cycling off!?
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  9. #9
    Join Date
    Sep 2002
    Location
    I don't know
    Posts
    2,909
    With the mod stat I think it waits until the temp is 2F below the setpoint before ramping up - seems silly to me.
    General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"

  10. #10
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    5,312
    "• If the differential is 2 degrees or less, the Heat Current
    Demand Status will show 50%.
    • If the specific Heat Requested Demand is above 2 degrees,
    the Heat Current Demand Status will track the
    specific Heat Requested Demand."

    It runs "first stage" if the the desired temp is under 2*.

    If above 2*, it modulates, up and down.

    Meaning during the middle of winter, without using programming, it will run 50%, and cycle, all the time.

    Which, is stupid. Which happens to be why we're not selling it.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  11. #11
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,594
    I can't make too much sense of it either. Key is getting the modulating communicating stat if you want the full comfort. But I still can't tell if it will run constantly and ramp up & down as conditions change like Rheem, Trane & Nordyne with their special controls do.

  12. #12
    Join Date
    Dec 2006
    Location
    toronto, canada
    Posts
    551
    Quote Originally Posted by BaldLoonie View Post
    So even though the stat says less heat is needed, it keeps blasting. So much for long run cycles on gentle, quiet low
    For 2 stage or their CTK1 tstat, if the second stage calls off and first stage stay on, it will not shift to low fire. I saw the picture of their CTK2 Tstat, It is identical to Rheem's new serial communicating modulating tstat. They said it will be full modulated if you use CTK2 stat.

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