We recently completed a geothermal conversion for a residential client in Honeoye Falls, Ontario County which turned out to be a great example of the adaptability of a geothermal heat pump system. The 25-year-old house included two stories and a full basement… plus a “bonus room” over the attached garage. The original propane-fired boiler distributed heat to 1st and 2nd floors and bonus room via conventional hydronic baseboard. Air conditioning had been accomplished by four mini-split systems – each had included an outside condenser connected to a ductless (evaporator) fan coil in each of the four bedrooms on the 2nd floor, but only one was still functional. There was no air conditioning on the first floor.
The client’s motivation to consider geothermal was three-fold:
- Eliminate the relatively high cost of heating with propane
- The aging boiler would likely need to be replaced within the next few years
- Provide air conditioning throughout the house
We started by modeling the space and water heating systems for the house… and estimated that converting to geothermal would save approximately $1500 a year versus $1.99/gal propane.
The design included re-using the existing baseboard for heat but given that geothermal hydronic temperatures are limited to about 140F (versus 180 to 200F from the boiler), we need to augment that. Since the existing air conditioning system needed to be replaced, the obvious choice was hydronic air handlers which could do heating (to supplement the baseboard) and air conditioning. Given the physical restrictions of the house construction, our air handler plan comprised the following:
- For the 2nd floor, we installed a ducted air handler in the attic (and found a path from the basement to the attic to run supply and return lines of 1-inch pex tubing to provide hot or chilled water).
- For the 1st floor, we opted for one ductless hydronic fan coil centrally located. Most of the 1st floor was fairly open between rooms, facilitating distribution of conditioned air. The one exception was the family room, but our modeling showed that the family room had enough baseboard to provide adequate heating even with lower water temperature of the heat pump.
- Unfortunately, the bonus room (on the 2nd floor and over the garage) was not accessible from the attic, so we could not utilize the ducted air handler to heat it. There we installed a 2nd ductless hydronic fan coil to provide air conditioning and 2nd stage heating.
The heat pump we chose also had the capability of providing 100% of the potable hot water demand, so we included an indirect hot water tank in the design.
After tuning the control system, we were able to provide the client space heating and cooling, and potable hot water heating; reduce his energy bill substantially; and eliminate his household need for fossil fuel.
Lake Country Geothermal, Inc. services the Finger Lakes and Greater Rochester NY areas providing quality and customized geothermal designs and installations to areas like Honeoye Falls, NY.