Happy Geothermal owner for the last three years. Tranquility 27 (Lake Loop) with Ecobee Smart Si. Some say longer runtimes and some say not. I have switched my Ecobee settings from a 30 minute Stage 2 runtime to a 3 hour Stage 2 runtime. I will be tracking any potential savings over the winter coming. Can you have too long a runtime? Will the ground around the loops "freeze" up and offer up no more heat? I recently read a post where the lake loop will extract heat from the "warmer" stratified water surrounding it, then as the water cools, it begins to ascend and warmer water replaces it around the loops. Our Bay is fed from a river as well, so does this bode well for Geothermal? Not looking to get into loop temps and super detailed info, just a home owner looking to get the most out of our Geo system. Looking to minimize Aux heat as much as I can. Thanks, Scott
Your conversion from 30min to 3 hours is how long it will run in Stage 1 "before" engaging Stage 2. Your heat loss (outside temperature vs. inside temperature) will dictate how long the unit will run to try to reach or maintain your interior setting. Stage 2 limiting (of 3 hours) may lead to some temperature swings in the house. So, I wouldn't necessarily, for comfort, have such a long time before engaging Stage 2. It's stage 3 (electric heat usually) that you want to pay careful attention to. All the mucking about should have limited effect on your "well designed" lake loops.
I do not think run times will cause depletion of BTUH in the bay or lake. Think about heat transfer not electric bills.
Stage 1 is set for 15 minutes. Stage 2 is now 3 hours. We get up to -30C up North here and Stage 1 is not enough. Stage 2 kicks in and the fan speed increases and the comp kicks in (nice even heat and massive air flow). I asked an Ecobee Rep about Reverse Staging and he advised not to use it.
OK that makes more sense now. Stage 2 kicks in after 15 minutes and will run until setpoint or trigger the next stage after 3 hours.
I thought it was and was really excited to try it out. I find that Stage 1 isn't very effective (especially at colder outdoor temps) or perhaps I am not giving it a chance. I usually set Stage 1 to 15 minutes because I like Stage 2 to kick in and give that warm blast of forced air quicker into the house. If the "stratified water" theory is correct, I just may up the Stage 2 runtime to 6 hours or more. Just looking for the optimal settings to minimize aux heat kicking on.
I too have a Tranquility 27, but with a Honeywell stat that does not allow me to specify length of time in stages like your Ecobee does. Once heating season arrives and I turn on the system, I set the desired temp and leave it there (i.e. no setbacks). From there, the stat handles the staging of the heat pump. From watching my heat pump stage up and down, I believe it's doing what it is supposed to. That is, at design temp, it's running 100% of the time on stage 2. When the outside temp dips below design temp, you should expect brief shots of aux to occur. Below design temp, it'll run stage 1 as needed and go up and down to/from stage 2 depending on the differential between set and actual temps.
Update Jan 2017 After extensive research across many forums, I set my Comp to Aux setback to 5c and Comp to Aux time to disabled. I have now enjoyed two straight days of no Aux heat while the outdoor temps have ranged from -10c to -22c. The loop is keeping up. I can't wait to see those Hydro bills go down!
Dec 2018 Update Installed a new Ecobee 3 Lite in Sept 2018. Installer wired it incorrectly and the result was Aux Heat only for Oct and Nov 2018. Hydro bills doubled. Re-wired and now no Aux Heat has been used at all during Dec 2018. Runtimes are still varying between 2 hours and 5 hours. Not getting long run times and concerned about short cycling. I am thinking I should drop the Engage Heat setting down a bit to encourage longer runtimes. Currently set at 1.8c drop. Don't want to have too big of a drop as comfort will be compromised. Added a ton of basement insulation as well so I am looking forward to tracking future Hydro bills now that I am back on track.
