Ontario Compressor Discharge Temps When Cooling vs Heating

Discussion in 'General Discussions' started by Tom6547, May 26, 2020.

  1. Tom6547

    Tom6547 New Member

    I'm brand new to this forum but mostly understand the principle of geothermal. I am NOT a DIY but like to observe and ask questions...probably a techs worst nightmare! Let me give you my geothermal background, such as it is

    I had a Commandaire 5-ton unit from 1991 until 2014, when my tech advised me that if it broke-down, parts would be an issue and it was old technolgy. It had a single stage compressor that still worked well (for 23 years) but was not available anymore. I also had a single tank setp for the desuperheater.

    So, in 2014 I upgraded to a ClimateMaster Tranquility 22, 5-ton, with all of the new computerized guts, 2-stage compressor, variable speed fan, internal loop pumps and all the rest. Very nice unit. And, I have the desuperheater running now with a two 60 gallon tank system in the standard configuration that's all over the forum.

    I live in Ontario, north of Toronto and this is a primarily heating climate. The house is a 2500 square foot bungalow and a finished basement. I'm in the country with a BIG front yard that's 500x400 feet. I have an horizontal 2500 foot, 1.25 inch black ABS loop in a switch-back desgin (not slinky) and it runs up and down the front yard, in trenches that were cut with a ditch witch. It covers the whole yard and then back into the house. It's 6 feet underground and has a 15% glycol/water solution and pressurized to 15lbs. When it was buried in 1991, the standard was 500 feet per ton. That may have changed nowadays but thats what I have.

    So, all is running well... lots of heat and lots of cold. So here's the question:

    I have noticed in heating that the compressor discharge temp gets up to 180-182F after about 20 minutes and the hot water EWT from the buffer tank rises steadily to about 130F and then holds unless theres a need for hot water. The unit consistently picks-up 6-7F degrees from the loop. The air into the house is usually 90-92F.

    In cooling, I have noticed that the compressor discharge temp is way down, usually between 120 to 130F. The EWT from the buffer tank never gets much above 90F . The air to the house is 45-46F and it's dumping about 11F degrees into the ground. So, it's definately cooling but I'm curious why the discharge temp is so low and therefore, not making much hot water.

    Here's a pic of the thermostat system info after the unit had been running in cooling (stage 1) mode for 4 hours with 88F temps outside.

    GSHP Status.png

    Is this a normal situation or is something not quite right?

    Thanks for any info you can provide and sorry for writing a book!

    Last edited: May 26, 2020
  2. mrpac

    mrpac Member

    Hi Tom, I too am in northern TO area with the same setup, except I have a 3 T 27.
    I can't see a screen like you have displayed on my Climatemaster Thermostat. I wanted to simply compare the specs provided by the controller.

    Possibly you have a different data board or something that was upgraded?
  3. Tom6547

    Tom6547 New Member

    Howdy mrpac: There's a bit of button-pushing to get to the system status screen. It may be hidden in all of the other stuff on yours. I do Menu>Settings>Service Information>System Status and there it is. But, your mileage may vary! ;) But, there should be some kind of status display somewhere, I would think, with all of the computer controlling going on.

    It's the original thermostat, right out of the box.
  4. SShaw

    SShaw Member

    I saw your similar post on hvac-talk. I think you'll find more expertise here.

    Yes, this is normal.

    I suggest you look up the performance documents for your unit on the Climatemaster website. You will find the hot water generator capacity listed as a function of EWT under the performance data. It's listed for both heating and cooling modes. You will see that the hot water output is low for 60-deg incoming water, and about half compared to output in heating mode at the same EWT. The output will increase as summer progresses and your EWT goes up.
  5. Tom6547

    Tom6547 New Member

    Ok, I'll look up the specs and see what's what. Thanks for the info!
  6. ChrisJ

    ChrisJ Active Member Forum Leader

    Ditto what SShaw said.

    On that thermostat if you press and hold the left arrow it should go right to that screen.
  7. Tom6547

    Tom6547 New Member

    @ChrisJ: It does so!! Who knew? :) Thanks for the shortcut.
  8. ChrisJ

    ChrisJ Active Member Forum Leader

    Your welcome, not sure where I got the info, I went through all screens to get there for 2 years....Lol
  9. Tom6547

    Tom6547 New Member

    Yea, that happens to me all the time!

    Would you or anyone else happen to know what the LT1 and LT2 temps are? I can't find any info about that....well, at least none that makes any sense to me :confused:
  10. SShaw

    SShaw Member

    Water and air temperature sensors.

  11. Tom6547

    Tom6547 New Member

    Excellent! Thanks a lot for the info. I've often wondered what they were.

  12. mrpac

    mrpac Member

    Funny, my thermostat doesn't react like you have indicated.

    Service information only includes 3 variables, and Fault history.

    Attached Files:

  13. Tom6547

    Tom6547 New Member

    Oh, I guess you must have a different version of the software or thermostat, although it is identical to mine. Try holding down the left arrow for about 3 seconds and see if that take you to it. That was a shortcut suggested by another poster. But, you may not have the software.

    Hunt around....they might call it something else
  14. geoxne

    geoxne Active Member Forum Leader

    You mentioned previously that you have a T27. The System Status with temperatures and other info was not available until the DXM digital control board was introduced with the T30 and T22 digital models. That function also requires the communicating thermostat. Your thermostat looks like the one posted by Tom but is totally different in every other way.
  15. mrpac

    mrpac Member

    Thanks Geoxne,. Valuable information.

    Do you know if the new DXM board is a direct replacement for my non-communicating board? I have read several other posts where option boards and other items were added over the years, and wonder if it might be a worthwhile investment if it is a direct replacement.

    Sorry for hyjacking the thread,

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