Published Sunday February 8, 2015:  Updated March 8, 2015

Two Years of Ground-Loop Heating and Air Conditioning

It’s been 2 years since we ripped out the natural gas furnace and replaced it with a super efficient ground-loop heat pump.


Nothing eventful has happened since that time. The heat pump equipment just does what it’s supposed to do and our house is kept at room temperature without anyone knowing any different.


In December 2014, we had a cold-snap where the outside temperatures dropped into the single digits, (°F) and the wind chill was -22°F. The heat pump ran solid in state 2 all night while the house stayed at a comfy 70°F inside.

With all that heating, the passive tank on the hot water generator heated up 11 degrees F above what the regular electric water heater tank was set at. Even with tons of showers, laundry, dishes and cooking, the hot-water heater never kicked on once that day.

While the temperature of the fluid going back into the ground got as low as, (44.2 °F), the ground loop itself never dropped below (49.6 °F).

In the summer time, the temperature of the fluid going back into the ground got as high as, (81.5 °F), the ground loop itself never rose above (72.9 °F).

While I consider myself extremely fortunate to have our household, (and my wallet) benefiting from this technology, I only hope that economies of scale will continue to play into this market until it is considered financially foolish to not build a house without a ground-loop HVAC system. For me, that was already the case. Our neighborhood sits on lake Bonneville sediment and that makes the drilling process easier and the drilling costs much lower. Had the soil contained layers of bedrock, costs would have been much higher and I probably would not have been able to justify getting a Geothermal Ground loop system. Currently drilling costs range from $15 to $30 per lineal foot of vertical loop.


I also hope the number of geothermal installers will increase to match demand. This technology is just too AWESOME and reliable! Why on Earth are we still burning fossil fuels for heat, (like tenant farmers burning fences), when we have almost limitless solar energy stored in the ground below our feet?




Problems:

The following tiny problem has happened three times now in past two years. Twice in 2013 and once in 2014. I suspect it is caused by brown-outs.
We woke up one morning to the house temperature sitting 4°F under the set-point, (66°F instead of 70°F). The blower fan was running but the heat pump was not. Turning the circuit breaker off and back on again reset its brain and the heat-pump was back up and running as if nothing had happened. Only this time when the heat pump cycled off, the fans remained on continually at maximum RPM. Something happened to the parameters programmed in the heat pump. I changed the program from the thermostat to correct this problem. Weird!


Overall, we are extremely pleased with our wonderful ground-loop heat pump. I look forward to many more years of comfortable, quiet, super-inexpensive heating, air conditioning and nearly free hot water. 

Energy Usage: For 2014, it took 3517 kWh in energy for both heating and cooling using the Geothermal, ground-loop heat pump. Assuming we didn't have solar panels, (and as you recall we no longer subscribe to natural gas), that works out to about $29/month in energy costs. 
1779 kWh went toward heating (Jan-April and Nov-Dec 2014) and 
1738 kWh went toward cooling (May-Oct 2014). 

How interesting that energy usage between heating and cooling is almost perfectly split. ~1:1
In the winter time, with colder temperatures, it actually takes more energy to keep the house warm vs keeping the house cool in the summer time. But since the heat pump is more efficient at heating air vs cooling it, it works out that the seasonal energy usage is almost even.