I'm the second owner of a 3500 sq. ft. home with a geothermal HVAC system. The home is built on a slab with 10' ceilings. The heat pump and all ductwork (insulated flexible ducts) are located in the attic. The system currently has three zones. I have been happy with the comfort (except for the compressor noise) and cost of operation of the system---- in all but the very coldest weather. When the outside temperature goes below about 10 degrees the electric consumption skyrockets because the auxiliary electric heat cycles on a great deal. I am trying to determine what "minor" changes I could make to reduce the amount of time that the auxiliary heat is on. I am not a HVAC professional, so I need some assistance in understanding how my system functions. My heat pump is a Climatemaster Tranquility 27 model TTV049 The three thermostats are Honeywell TH8320 The zone control is a Jackson 300HPS I can monitor my electric consumption by using the daily consumption figures provided by the local electric utility. Degree day information is readily available on the internet. I don't have much additional information about the system since I am the second owner of the house. I do know that it is a closed loop system with four vertical wells of unknown depth. The system is regularly serviced by the company that installed it, but I don't have any specific information on pressures, temperatures, etc. The rather loud compressor noise transmitting thru my ceiling lets me know when the compressor is running---which is nearly constantly during very cold weather. The thermostats tell me whether a zone is calling for heat---but do not tell me whether the compressor is on the first or second stage. The only way I can determine whether the compressor is running on the second stage is by viewing the lights on the zone control panel. This is a problem for me since the unit is in the attic and I don't climb stairs well. The thermostats also will show an "aux heat on" message at times. This message may be shown on only one thermostat, two thermostats, or all three thermostats. The home was built for a disabled man and his elderly caregiver. It originally had two zones. One was an "enclosed porch" with is a long, narrow room with mostly glass (windows and atrium door) on two sides. I think that it was intended for a spa/exercise room of sorts. The second zone was the remainder of the home. The thermostat was located in a "dead air" zone in a hallway between two bedrooms. Sometime after moving into the home the man decided that he liked his bedroom cool and his caregiver liked her areas very warm. They had the main part of the home divided into two zones with a second thermostat located in a hallway outside the other two bedrooms on the far side of the house. We have set the "porch" zone at 62 degrees because we don't use it often. The other two zones are kept in the 65 to 67 degree range---depending on how we feel on a given day. We do turn down the zone where our bedroom is located to 64 degrees during the night because we sleep better with a cool temperature. In very cold weather when we turn the thermostat back up to 66 the temperature seems to rise to about 65 degrees, then drop back to 64 degrees and the "aux heat on" message will appear on the thermostat in one of the other two zones. When I walk around the house there feels to be very little air flow from any of the ceiling registers. I suspect that increasing the set point on one thermostat is causing the auxiliary heat to kick in, and that the hotter supply air is stratifying near the 10' ceilings and not reaching the thermostat that was recently changed. I have looked a the programming on all three thermostats. They are identical with a first stage cycle rate of 3 and a second stage cycle rate of three. I have noticed that the system may run for an extended time with the "aux heat on" message showing on one or more thermostats, then the system will shut off for a few minutes. (All thermostats have the compressor protection set for five minutes off). The heart of the matter is that I don't understand how the three thermostats function in combination with the zone control. Can someone explain: 1. What controls the progression through the stages? (is it based on time or temperature differential?) 2. The auxiliary heat is either on or off. Why don't all thermostats show the "aux heat on" message when the auxiliary heat is on? 3. I'm not really concerned with temperature on the enclosed porch (as long as it stays above 55 degrees). With all the glass, it's the zone most likely to drop below the set point. Can I change something to prevent a small temperature drop in this one room from causing the auxiliary heat to come on? 4. The compressor does seem to cycle on and off even in zero degree weather. I don't know whether it is cycling between 1st and 2nd stage. Is it possible (or likely) that this cycling coupled with having multiple zones is causing the system to use the auxiliary heat rather than the 2nd state heat (because of the cycle rate specified?) 5. I don't currently have a way to measure static pressures in the system or the cfm delivered at each register. With ceiling registers and 10' ceilings the warm air seem to stay above my head level. Would increasing the blower speed help (if it is possible?) 6. I like the ability to keep the enclosed porch at a different temperature than the rest of the house---so long as it doesn't increase my costs by causing the auxiliary heat to run more. Would it be more efficient if I recombined the other two zones? (The only reason we keep one zone hotter or cooler than the other is an attempt to save money.) 7. Based on the information I have presented, does anyone have any suggestions what else I should consider?
I'll try an answer some of the questions I'm not sure with this tstat.. but with most, moving the temp by more then 1 (or 2 ) degrees can cause the aux heat to engage. ie dropping the bedroom to 64 at night and then rising it to 66/67 in the morning could be costing you more then just leaving the tstat set at 66. Most tstat have one way communications... the unit does not inform them what it's actually doing. The aux heat msg will only appear on the tstat that is requesting aux heat at the time. Well you could unhook the 'W' (aux heat) connection for the porch tstat.... but it's unclear if it would maintain 55 degrees or not. You would need to try and see. Maybe keeping the fan on would help in general? (at least in the non porch zones) It's quite possible that when the added the 'extra' zone they turned down the air flow (or added in a bypass) to prevent excess air noise. Increasing the blower speed could improve the efficiency of the system. When they service your system, do they calculate the system performance?
Thanks for the information dgbair. The Honeywell TH8320 literature states "The second stage energizes when the thermostat senses 1st stage is running at 90% capacity. This operation is droopless control" I don't have a clue as to what this means. The tstat has some programmable settings. One is 0680 Temperature Control in Heat. The standard setting is 2. Less aggressive temperature control is 1 and more aggressive temperature control is 3. Perhaps I should change my settings to 1---at least for the zone where I set back the temperature at night. What confuses me is that the "aux heat on" message may appear on the tstat(s) that are showing that the temperature is at the set point. The message may not be displayed on the tstat where the temperature is less than the set point. I would rather avoid changing the wiring to determine what might work. Could I defeat the auxiliary heat on the porch tstat by reprogramming it as a 2heat/2cool (rather than 3heat/2cool)? Putting the fan on the "ON" or "CYCLE" settings seems to create more problems than it solves. The "fan only" speeds are fairly low compared to the speeds when the heating or cooling is on. The ductwork is in the attic. Running the fan without the heat being on seems to produce a cold draft in very cold weather. It produces a hot draft in the hot summer weather. Whoever designed the system seemed to place the diffusers where they would blow on the most likely spot to place a bed or chair. (It was probably the same person who put the wall electric outlets directly behind a large, heavy piece of furniture!) Most of my rooms have ceiling fans. Running them in reverse (blowing the air upward) seems to help when the auxiliary heat is on, but just creates a draft when the heat goes off in the zone. The system has a bypass (I'm not sure whether the reason is to reduce noise, limit static pressure, or ???? I'm not sure what is done when the "service my system" It seems like there is a different serviceman nearly every time. They prepare a "service invoice" and give me a carbon copy . The handwriting generally looks like my doctor's handwriting . The latest one where I could actually read the writing said: PMH on GEO -Checked Aux heat -Checked zone board and dampers -Replaced filter -Checked water pressure in and out 26 and 19 Geo operating properly at this time I'm beginning to suspect that I should try another company. I have complained about the excessive compressor noise six at my last six service calls. I was always told that they had examined the system closely and that there was nothing they could do to improve it. Last week I decided to take a look myself. The shipping bolts on the spring mounting for the compressor had never been loosened. When I loosed the bolts, the noise transmitted through my ceiling dropped by a major percentage. Unfortunately, my favorite chair in the house is about 8' away from the spot directly under the compressor. What should I expect to get with a semi-annual "service"? The service is always scheduled at the beginning of the cooling season and the beginning of the heating season. My only real complaints are in the very coldest weather. One additional thing that I noted in the tstat literature. It said that the tstat should be mounted 5' above the floor. The original owner of my home was disabled and the tstats were mounted 4' above the floor. In terms of heat stratification (heat rising), this doesn't seem to be the best with tall ceilings, ductwork in the attic, and a relatively cold slab floor.
"I would rather avoid changing the wiring to determine what might work. Could I defeat the auxiliary heat on the porch tstat by reprogramming it as a 2heat/2cool (rather than 3heat/2cool)?" https://customer.honeywell.com/resources/techlit/TechLitDocuments/69-0000s/69-2733EFS.pdf Based in this set up literature, on page 6 it says that you can set the stat to system type 11 (heat pump with no aux heat) or 12 (heat pump with aux heat). If it is wired correctly, and you change the system type from 12 to 11, your aux heat will not come on.
Yeah, what Tamar said.... but I'm assuming the pdf she pointed to isn't the tstat you have? She pointed to a Wi-Fi model which has some nice options.... but I'm assuming you have the older non-Wi-Fi model? That confuses me as well....
WiFi or not shouldn't matter, all T8623s should be wired the same. It's been over 20 years since I worked at Honeywell, but even back then the thermostats had algorithms that "learned" what it would take to keep a room close to set point. If the stat has learned that it "needs" the aux heat if the temp doesn't rise above setpoint, then that's perhaps what it is supposed to do. Is it set to comfort or economy? (economy will allow for more of a swing). We had a T8623 for 3+ years before switching to Danfoss valves a few months ago, and my husband was sure that the stat was displaying the temperature incorrectly because if we changed the setting (by a degree or 2) sometimes the display temp would change immediately with no change to whether heat was actually being called for. I chalked it up to liberal "rounding" of the temp reading. As far as the aux heat not being on when the temp is less than the set point....how long has the temp been less than setpoint? There would typically be some period of time when the stat would attempt to recover to temp without bringing on aux heat.
I was just about to start a thread with the same title. I too have a Tranquility TTV. Mine would seem to be a bit smaller, 038. My thermostat is a ClimatemasterATP32U04 controlling just one zone. Like RetiredIn I'm pretty satisfied with my system but in this extreme cold (-35C) I wonder if the system is working as well as it should. Normally I operate with the Aux heat turned of (I do it at the breaker) and can usually maintain the house at 72F up until the outside temp hits below -30C. At that point if I don't power up the Aux heat the house will fall down to 70F even though the unit is running constantly (22hrs at last count). When it gets like this I usually run down and monitor my loop temps and air duct temp. What I have noticed the last three times I have done this, the outside temp was -29, -34 and -35C. Each time my EWT and LWT dropped (33/25F, 31/25F and 30/24F) but the difference stayed about the same and my duct temp stayed about 90F. I was thinking that as the loop temp dropped, even though the diff stayed the same, I was not getting the same amount of BTU but since the duct temp is remaining at 90 that would seem to blow that theory. The house is super insulated with WallTite Eco foam (6" in the roof and 4" in the walls) but I'm inclined to think that the insulation has it's limit and -30 and below is pushing that limit. Any comments? I'm also curious as to Tamar's comment. How does a thermostat 'learn' the house. Mine has 3 possible heat algorithms and is set to Integrated Proportional. Tamar, are you saying that over time the behavior of this algorithm changes and what causes this change i.e what does the thermostat learn? Is this learning an ongoing process?
Tamar, are you saying that over time the behavior of this algorithm changes and what causes this change i.e what does the thermostat learn? Is this learning an ongoing process? Well, my knowledge of what "smarts" Honeywell builds into its stats is from the '90s, but I used to answer the 800-number consumer and contractor line to help with the choice and programming and troubleshooting of thermostats. I took tons of calls on T8600s and T8602s. In programming those stats, you would set the time you wanted the house to BE a certain temp (e.g., if you wanted it to be 68 degrees when your alarm went off at 6:30am, that's exactly what you'd program). Then, the stat would "experiment" with bringing the heat on at certain temps X how much time it was until you wanted it to be 68 degrees. If it was 64 degrees at 5:30, it would turn the heat on and see how close it was to hitting 68 without overshooting at 6:30am. The next day it would adjust the time it came on, and so on. It also "understood" that conditions were not constant and would make adjustments as mornings got progressively colder/warmer. If you had a day or 3 that were real outliers, the stat would not perform as accurately. I have to assume that the technology has gotten even more complex and accurate, but that there are more conditions that might cause an occasionally perplexing reading.
In your case the Jackson Zone panel is in charge of staging. Your thermostats tell the zone panel what it wants and the zone panel decides what control signals to send to the equipment. I am not familiar with Jackson and I found no documentation that explains their staging control logic or any way to adjust it. It is very possible that a zone panel can make a "smart" thermostat dumb in relation to the equipment being controlled. Every model zone panel and manufacturer have there own control scheme, some proprietary, some documented and some configurable in setup. Most commonly staging is based on elapsed run time ie. 20 min between stages. Some zone panels can stage based on % of zones calling. Some allow staged tstat signals to pass through. Others might use a combination of strategies.
Thanks for your reply Tamar. Your explanation sounds similar to how Nest tStats work. In the case of a geothermal stat where the setpoint remains constant and the unit runs constantly I have a hard time trying to imagine how the learning can be done although I have heard from others where they said their installer set the thermostat to an agressive cycle until it could learn the house. This agressiveness manifested itself as shortcycling. I have looked at the settings , including the installer settings, and aren't sure how this can be accomplished. I have experienced something that you mentioned where the unit was running for over 20 hours at a set point of 72F and read only 70. When I shut the unit down to check some settings and then re-started it the thermostat read 74F and did not call for any heat. Just a fluke or a faulty tStat?
I have experienced something that you mentioned where the unit was running for over 20 hours at a set point of 72F and read only 70. When I shut the unit down to check some settings and then re-started it the thermostat read 74F and did not call for any heat. Just a fluke or a faulty tStat? I'm not sure. It's sounds "wrong", but to me, the important question is whether the stat is keeping the area that it is meant to control comfortable. If it's keeping your unit running to the point that it regularly overshoots the desired temp, it's faulty. If the "thermometer" reading is sometimes off, but the stat is maintaining a comfortable room temp, then that's less of a problem. For all we know, maybe Honeywell has build in a "feels like" temp that takes humidity into consideration, but the thermometer display doesn't reflect that. It may be worth a call to the 800 # on the stat itself (that's the one I used to answer), just to satisfy your curiousity, or maybe you can even send an email or chat online with a rep these days. I will warn you that back in the day there was an average 45 minute hold time to get through to one of us.
I think Geoxne is on the correct path. I now the Arzel zone panels I use look at both ODT, (outdoor temperature, with an outdoor sensor) and LAT, (leaving air temperature with a sensor in the supply duct work). One then tells the Arzel board what is wanted when and at what temps and the board "thinks about" what to do to make you happy. Arzel uses dumb on off thermostats from each zone. If I am using an ECM blower system I need to program the blower speeds from my laptop or Stephanies table. I do not know about Jackson, except as a company with that name retro fitting their system on Trane veritrack proprietary control systems. Do you have any books? Have you looked online for info? You could pop the cover and look at the wiring print for sensor input above and beyond the zone stats. Look for ODT and LAT inputs. I have used Tamar's stats and they may be too "smart" for the zone control. Since above and beyond the zone satisfaction, I have no idea about Jackson. Hope this helps. If not PM me here or call me. 440.223.0840. Mark
The circuit board has an 11/3/03 date stamped on it. The Jackson Systems website has information on a later model. I contacted the company and they emailed me a copy of the installation manual for my older model. It seems to say that the thermostats will control the heat. When any thermostat calls for heat the equipment will be powered up. Zones not calling for heat will have their dampers power closed by a damper motor. The only other (than for the thermostats) input terminals were for some sort of maximum and minimum "controls". I'm assuming that these are would be needed if the thermostat didn't have maximum heating set limits and minimum cooling set limits
