Hello everyone! I'm new to the forum, so please be kind (:

I moved into a new home this September. It's a 2200 sqft ranch near Boston, MA, built in 1964 and updated in 2008. It's 2200 sqft of living space (about 1800 upstairs, 400 finished and heated/cooled in the basement, and another 1100 unfinished.) It's heated and cooled with a geothermal pump, and the bills have been CLIMBING. I was told by the utility company that the highest bill last winter was $318 in January - my November bill (with a total average monthly temperature of 46F) was $319. So I think something is wrong.

I've filled out the starter guide below to the best of my abilities.

I will say that the system seems to be doing its job in the end, as the auxiliary heat isn't kicking on hardly ever (maybe once a week and only for a few minutes, according to my sensor data.) That being said, the bills - seem to point to something being wrong.

The only other note is that I suppose it's possible that the previous homeowners were constantly supplementing with wood (there is a small wood stove, though there's no evidence of any kind of mass wood storage), but with the current temperature/cost trendline continuing, I'm seeing this system costing $450-$500 a month in the winter to heat my 2200 sq ft house. Does that seem reasonable for a Geo heat pump system?

Please let me know your thoughts, or if there is more data that I should collect.

Thank you!! ~Jake

1) Where you live
Boston, MA


2) Heat loss/gain calculations for your home

Main level:
Total wall length - 168 ft
Wall height - 8 ft
19 Windows at 11.5 sqft
5 Doors at 19.5 sqft


Finished Basement:
Wall length - 45 ft
Wall height - 4 ft
Windows - 30 sqft

TOTAL Wall - 1524 sq ft Openings - 346 sq ft

Attic is insulated.

Total Heat Loss for 60F Temp. Diff. = 57,679.83 BTU/hr

(I will say that this estimate seems high, as the calculator that I used is assuming about 19k BTU/hr for infiltration, and I think my house is a bit tighter than that. But I’m really a newb and don’t know, so I kept the default infiltration values).

3) Brand, size (model), age and type of heat pump
Climatemaster Genesis GSV048AGC01JLTS
3/3/06
Electrical Coil supplemental (originally piped for hot water heater supplement, now direct electric coil)
According to the manual, this system has a 54,100 BTUh heating capacity as a water loop heat pump

More details: https://files.climatemaster.com/Genesis-GS-Series-Product-Catalog.pdf

4) Type of loop field
(open/closed/vertical/horizontal) size and design parameters
We aren’t 100% certain, but believe that it’s a closed horizontal system. There’s a single pump and expansion tank that has a pair of pipes that go out through the foundation wall, and there is a ‘field’ marked on the septic plot.

5) Average cost/Kwh of electricity and consumption
My utility rate is 21.79 c/kWh

Here is one full day’s consumption breakdown. The average outside temperature for this 24 hour period was 33F (with a low of 28F and high of 37F), and the thermostat was set to 68F for 8 hours and 69F for 16 hours. Note that for this region, this a "normal" or "slightly warm" day for winter, especially Jan or Feb.

Geothermal Compressor & Blower: 38.314 kWh (the blower consumes almost exactly 500W, and the compressor consumes 2,850W, making a combined total of 3,350W.)

Geothermal Well: 11.171 kWh Auxiliary Heat: .291 kWh (I bumped the temperature an extra one degree on purpose to ensure that this was reading accurately, and turned it back down immediately after the aux heat kicked on)

6) Entering and leaving air temperatures (EAT, LAT) measured immediately upstream and downstream of the heatpump

This was at the middle of the heating cycle - the thermostat is set at 69.

EAT: 70.8F
LAT: 99.6F

7) Entering and leaving water temperatures (EWT, LWT) measured at the geo system
Taken at the end of the heating cycle.

EWT: 52.8F
LWT: 48.2F

8) Percent of load to be covered by geo and balance point I don’t know the calculated balance point, but it looks like even on cold days, the auxiliary heat doesn’t run for more than 30 minutes. I have alerts set up to email me when this happens, and it’s quite rare.

9) Installer's assessment of your systems operation. We haven’t had anyone in to look at it yet.

10) Projected operating costs, actual operating cost and previous heating and cooling costs This is the concerning part - we got data from the utility from last winter, where the previous owner’s maximum consumption in the coldest month was $318. So far this year, our November bill was $319, and it was quite mild (average temperature of 46 degrees.) We’ve been supplementing with a wood stove this December to keep costs down, but even with wood burning, the geo is costing around $10 a day.

Sounds right to me. Geo to me has never performed to what it is advertised. I have had it in 2 homes and last year ran a comparison to Natural Gas and to wood, because they way my house is setup I can heat either way.

We spent $600 in wood to save $300 in heating using natural gas, so that was a $300 loss with wood.
Naturel gas was tested to be greater then a 80 percent savings compare to runnig the Geo.
So now we just heat with natural gas all winter long and have a fire for comfort when we want.

In our last house we were caught in a pricing change the power company made where they swapped the winter and summer rates on us. So the cooling rate was super cheap but the winter heating rate was through the roof. So check your rates and time of use.... Most have a second meter for geo and get a better rate and it also has a summer winter rate and a peak and off peak rate. Maybe you can use that to help.

Set your therm to only use the aux heat if you get like 2 or more degrees below your set point.

Your entering and leaving water temps are very close to me....might be wasting some pumping effort there...can you play with the pump speed get more temp drop? Or play to see which way is cheaper to maximize that?

Good Luck, We are near Ann Arbor Michigan for a reference.

I would also buy a cheap "Seek" or "Flir" thermal camera for like under $200 and go around the house with it and see what you can find. You might be able to seal some stuff up or find missing insulation.

https://www.amazon.com/FLIR-One-Thermal-Imager-Android/dp/B0728C7KNC/ref=pd_lpo_469_t_0/139-8365536-6797233?_encoding=UTF8&pd_rd_i=B0728C7KNC&pd_rd_r=d70b8d08-2277-4c52-944a-3618715a82a4&pd_rd_w=QkWG6&pd_rd_wg=1QwW1&pf_rd_p=7b36d496-f366-4631-94d3-61b87b52511b&pf_rd_r=T53RG5RHSPD09SSDSFFY&psc=1&refRID=T53RG5RHSPD09SSDSFFY