Saskatchewan Forever Curious

Discussion in 'General Discussions' started by BatocheBob, May 15, 2016.

  1. BatocheBob

    BatocheBob Member

    I have had my two ClimateMaster geothermal systems for almost 5 years now and have had my share of issues. My choice of geothermal was from necessity, I have no gas in this area and propane or oil were not good choices in my opinion. Generally I am pleased with my choice. My energy consumption seems to be good when I compare my bills with other homes of similar size in our climate. And although we have always been fairly comfortable I am still looking to reach a little better comfort level and still trying to manage my own expectations.

    Over the years I have received a lot of good information from this site and, even if it didn't always appear that way, I have appreciated that info and acted on it as much as I could. I have added an outdoor reset to my water-to-water side and I'm trying to work up the courage and budget to make some improvements to my manifold system. On the water-to-air side I have switched to an Ecobee thermostat.

    My question today is hopefully a simple one. I realize there can be many variables in heating scenarios but assuming a very well insulated house and a properly sized system what would be a reasonable time lapse from the call for heat to setpoint where the tStat differential is .03C and the outdoor temperature is 0C. Thanks.
     
  2. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Very hard to tell.

    At design temperature you, in theory, would have your equipment running at peak load forever to maintain your indoor temp setting.

    With your climate, a 0C outdoor temp is likely far less than 1/2 of your actual peak load demand. So you have a lot of extra tonnage available. But then you likely stage all your equipment so it would be operating at reduced output.

    And then there is zoning issues that can strongly influence this.

    So it is really hard to give a definitive answer but if your equipment is staging and taking 20+min to get there, I would see no concerns at all. If your equipment is not staging, has bad zoning, and is running flat out but not getting there in 20min, I would have some concerns.
     
    Last edited: May 15, 2016
  3. BatocheBob

    BatocheBob Member

    Thanks for your reply Chris. One of my concerns from the beginning was how long each heating cycle lasted. I have since learned that as it gets colder each cycle can be expected to get longer and, as you mentioned, at design temp it runs 100%. Just to clarify your term, when a heat cycle begins my pump starts in 1st. stage, moves on to 2nd. stage after about 10 minutes and reverts back to 1st. stage as I approach the set point so I would say I am staging. I guess why I am curious is last night, still with my ClimateMaster tStat, the temperature was 0C and rising and yet the system ran for well in excess of 4hrs before reaching set point. As it gets colder that time extends till it is running forever at -33C, which is fine . Is 4+hrs at 0C acceptable? In a more typical winter situation when it is -10C it will take about 45-50 minutes to drop 1 degree and then take 6 hours or more to recover that degree. During this extended period of time a person can get a bit uncomfortable waiting for the temperature to get back to the desired level. I will be installing my Ecobee sometime this week and expect a great improvement in my overall performance. I'm trying to see what a reasonable expectation should be.
     
  4. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Bob:

    Any idea what the EWT and LWT temps are?
     
  5. BatocheBob

    BatocheBob Member

    As a matter of fact I do. it was 34C & 29.4C. Thanks Mark
     
    Last edited: May 15, 2016
  6. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    How about the loop side?
     
  7. BatocheBob

    BatocheBob Member

    Guess I misunderstood you. Those readings were the ground loop. We are dealing with a water-to-air unit.
     
  8. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    Really ??? your loop temp coming out of the ground is 34° C. You must mean 34° F
     
  9. BatocheBob

    BatocheBob Member

    Sorry about that. i operate mostly in Celsius but my thermometer is F So yes 34F & 29.4F
     
  10. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I re-did my math and thought you might have been cooling. Using your F numbers I think you are good. A published rule of thumb from Climate Master is 4 to 8*F drop in loop temp in heating and a nominal 3 GPM/ton.

    Of all the moving target variables used to determine the health of a heat pump, run time is the least meaningful.

    Do you have an I/O for your machines?

    Mark
     
  11. BatocheBob

    BatocheBob Member

    Thanks Mark.s I recall at the beginning my expectations were high and my knowledge low. Over the past 5 years my knowledge has increased, mostly due to this forum, and I'm trying to manage my expectations a bit more. I did see my performance improve a bit within the first couple of years and was told that was due to the ground loop getting settled and improved heat exchange. I do agree and think I'm pretty good on the loop side and am hoping my pump is in pretty good shape. What I am mostly concerned about is the 'health' of my Wife;-) She is a lot more sensitive to the cold than me and notices the long periods of time when the room is not at the set point temperature. Many times I have measured my duct air temp at about 32C and can't understand why it takes so long to get the room back to set point. As mentioned I have just purchased an Ecobee and will be installing it shortly. What I'm trying to do here is determine what kind of elapsed time I should expect from call to set point. Besides some of the nifty smarts of the Ecobee the feature that attracted me the most was the ability to adjust the differential down to .03C I'm hoping that, along with the ability to manage the timing of 1st. & 2nd. stages, I can keep the room at a steadier temperature. Not sure if I'll cut down the total runtime but my expectation is I will. My logic says if it takes 30 or 40 minutes to lose a degree when it's -15C outside it shouldn't take me 4 to 6 hours to retrieve it given that the design temp of my system is -33C.
     
  12. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Your expectations remain contrary to good design, while it is not design practice to fall short of set points, it is often design practice to set staging up and back down based on demand. So one scenario that occurs often in our systems is:
    at .5F below set point, stage one is activated and will continue to operate until thermostat is satisfied.
    If temp falls to 1F below set point then stage 2 is activated and will continue to run until house temp is within .5F of set point.
    Once within a half degree stage 2 shuts off and stage one remains on until thermostat is satisfied.
    If stage 1 is maintains within .9F of set point unit will neither shut off nor activate stage 2

    For those who don't understand the design, this gives the system the appearence of "struggling to keep up". What it really is, is using the least amount of energy to maintain set guidelines and giving the home supperior comfort without the temperature peaks and troughs associated with old single stage equipment.
     
  13. BatocheBob

    BatocheBob Member

    Joe,

    Thanks for your comments. I'm not sure I understand your comment 'your (mine) expectations remain contrary to good design'. I have admitted several times that my expectations could very well be too high, or as you put it 'contrary to good design'. Perhaps it is normal, after spending $50,000+ on a heating system, to be a little uncomfortable for a few hours while the heating system gets the house back up to set point. Personally I don't think that is acceptable, especially when I have to listen to my wife tell me how cold she is. I have talked with my dealer/installer several times and after a few attempts to improve the situation he has suggested I get a new thermostat, which I have done. What I was trying to accomplish with this thread was try and get a good educated opinion on how long I might expect my system to recover 1C given that it is 0C outside and assuming that my system is designed correctly. I find it unusual that it takes me approximately 1 hour to drop 1C but it then takes 4+ hours to recover that 1C. During that recovery period it can sometimes get a bit uncomfortable especially when it's colder and the recovery period is much longer, I had one suggestion that if my system is properly staging, which I think it is, 20+ minutes to recover 1C at 0C outside temp is not a concern. To me 20+ minutes suggests possibly up to 40 minutes, or even 60, which is a long ways from 240+ minutes.

    In relating your scenario for good staging you refer to .5F differential. Unfortunately, to the best of my knowledge, a ClimateMaster thermostat can only go to 1 degree differential regardless of whether you are set for C or F. This is the main reason why I accepted the suggestion of an Ecobee tStat; it can go as low as .05F (.03C) which I'm hoping will help even out the room temperature and cut down on the recovery time.

    I do understand that once the outdoor temperature has dropped to my system design temperature (-32C) I can expect the system to be running constantly in order to maintain setpoint and I can even understand that when we have approached that point, or possibly lower, I could start losing ground and require some supplementary heat. So if you still think my expectations are contrary to good design I will have to accept that;-)
     
  14. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    So your system running, I'm assuming, is the zone valves calling. Not necessarily the heat pumps running for that time period? If your heat pumps are running 4 hours straight during your example, then yes, something is off.

    I haven't gone back and digested all this, but if you're radiant supply temps are too low, then you will have a hard time reaching temp. That can be a fault of the algorithm in the control if you're using outdoor reset.

    For example:

    -20C I want tank water to be 45C
    + 15C I want tank heat off

    So then some proprietary calculations are done and you may find at -2C then machine only wants to put out 32C water. Depending on your design, this may not get you there.

    So, with these controls, either set a minimum tank temperature. Or make your outdoor design temperature warmer (say -10C). The tank then gets 45C at -10C out and the algorithm adjusts all the in-between temperatures accordingly.
     
    Last edited: May 23, 2016
  15. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Keep in mind that a good designed system shall be keeping (holding) your temperature at the coldest year of the year, but should not be designed to recover to much, as Chris mentioned.

    Sometimes a radiant system is slow responding, what we call thermal inertia, meaning you have to heat up the floors first to heat up the space. You don't want the temperature too hot either, since now your floors short cycle between hot and cold.

    Ideally you want your call to be almost alway on, for an even heat, and have the outdoor reset regulate the water temp up and down, so you heat less on warmer days.

    That way it is most efficient and most comfortable.

    Now throw solar gain, or wind into the equation, and things can be off. Some more complex controllers have outdoor have an algorithm build in where they measure the speed of the outdoor temp drop, so they preheat the buffer tank in anticipation of a higher load, or make the supply water warmer.

    The nightmare scenario is no clouds, solar gain stops at night, cold clear sky winter night, house cools down, all the floors call for heat at the same time, heat pump needs to heat up the floors plus the space. That is why a water to water system needs extra capacity to overcome the thermal inertia quicker. Now you want to slow things down (staged heat pumps) through the night. In the morning then the opposite effect, solar gain through the windows heats up the warm slab further, temps in the rooms overshoot, causing system to shut down completely until nighttime.

    High mass radiant system is slow responding (thermal inertia). That is why you want a really smart control system, not just a thermostat.
     
  16. BatocheBob

    BatocheBob Member

    Sorry gentlemen, there may have been a lack of information on my part. In previous threads we had much discussion about my hydronics system. In this thread it is my water-to-air system that I am referring to. There are no valves involved. The tStat calls for heat and the heat pump fires up and runs for 4 hours or more.

    My water-to-water unit that runs my hydronics is a single stage pump with a thermostat for each zone. In spite of the inefficiencies that have been identified the hydronics side actually performs better than the air system possibly because it mostly heats the unfinished basement and garage and they are kept at a much lower temperature than the rest of the house I never worried about it until I implemented the last zone which heats my ensuite and laundry/mud room. That's when I identified a bit of a short fall but now were getting back to my previous thread from a few months ago. Since that thread I have bought an outdoor reset for that system and tweaked the flow valves a bit but unfortunately the heating season is finished so I'll have to wait till next winter. By that time I may have also made some improvements to my manifold system.
     
  17. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Measure your heat extraction. That will tell you if your equipment is OK.
    Again, on the coldest day the system should maintain temperature, not catch up and satisfy the thermostat.
     
  18. BatocheBob

    BatocheBob Member

    Thanks for your reply Doc. I'm assuming that you are referring to EWT & LWT with regard to heat extraction. On one day recently when I monitored this closely my temps were 34F & 29.4F which I think suggests fairly good heat exchange. Also If I remember correctly my duct air temp at the room outlet was 90F.

    You mention maintaining temperature and not catching up. I'm not sure how that works. I thought the whole idea of thermostats was to shut the system off when setpoint was attained and then startup when the differential temperature was reached. Here is where I'm hoping the Ecobee, with it's finer differential (.03C) will minimize this 'catch up' and maintain a more constant temperature. I'm also hoping that with only .03C of catch up the system will be able to satisfy this in a more reasonable time. Thanks.

    PS I'm assuming you checked into the security error I experienced. Thanks.
     
  19. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    You need delta T (EWT-LWT) x flow x 485 = heat extraction in BTUs.

    The delta T means nothing if you do not have the flow. 4.6 F delta is in the range where one would expect it at the right flow, but since you don't know the flow......
    Also 90F at the duct outlet is in the range. But again, at what flow rate, in first or second stage, or with the supplement heat on?

    Finer differential can cause more short cycling, ideally it runs continuously at a certain stage, assuming you have a multistage heat pump. It also throttles back to first stage when it hits that second differential depending on the algorithm, and then runs in 1st stage until it hits the next differential set point and shuts off, so it would be normal to continue to run much longer since it now runs only at first stage.

    All that would be normal and desirable for comfort and energy efficiency.
     
  20. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Did you add the water coil to the ducted system?
     

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