Homes on Providence’s historic East Side often come with an enviable address, lovely views and antiquated heating systems. Such was the case last year with a 12,000-sq.-ft. home on the East Side with a view overlooking the state capitol. A new buyer decided to completely renovate the home and install a new HVAC system using state-of-the-art technologies including geothermal, in-floor radiant and hydro-air.
Going with Geothermal
TJ’s Plumbing and Heating, Inc., Attleboro, Mass., a firm with expertise in designing and installing geothermal, radiant and solar thermal systems, was the HVAC contractor awarded the contract by the owner, in conjunction with the home renovation contractor, Parker Construction of East Providence, R.I., which specializes in custom luxury homes. Tim Cutler, owner of TJ’s, has been doing geothermal installations for around 10 years, mostly for high-end homes, both new construction and retrofits, and he has seen a 30% growth in his firm’s business stemming directly from geothermal.
With an aged heating system fired by an oil-fired steam boiler, coupled with the new owner’s desire not to have any HVAC equipment situated outside the home for aesthetic reasons, TJ’s challenge was to deliver the ultimate comfort system without compromising the home’s integrity. To accomplish this task they provided a design-build alternative energy system for both heating and cooling, attaining a comfortable indoor environment year-round with a water-to-water geothermal system as the centerpiece of the home energy system.
According to Cutler, vertical bore holes work best in New England’s rocky soil. With sufficient property available for drilling six 550-ft. bore holes for the geothermal system, TJ’s selected and installed three Bosch-FHP 6-ton, two-stage water-to-water TW071 Series heat pumps in the home’s mechanical room. TW Series units feature a two-stage scroll compressor and floating base pan for quiet, high efficiency performance. Unless peak capacity is required, the units can run at roughly two-thirds capacity, at significantly higher efficiencies than other geothermal heat pumps. For backup heat and domestic hot water needs, TJ’s installed a Viessmann gas-fired condensing boiler.
The home has a total eight bathrooms on three floors, and to keep its floors warm underfoot, as well providing in-floor heat for most of the first floor, TJ’s installed a Viega radiant heat system. The firm also installed seven zones of hydro-air using chilled water for cooling and 120° design water temperature for heating. Custom designed sheet metal was used to fit into the home without compromising the home’s integrity or elegance.
Ensuring high indoor air quality
To ensure the highest IAQ and to also provide radon removal, TJ’s installed a Zehnder ComfoAir 350 unit to constantly change the home’s indoor air. This system works continuously to extract moist, stale air from wet rooms (kitchen, bathrooms, utility rooms and closets) and supply fresh, filtered air to habitable rooms. Up to 90% of the heat in the extracted air, which would otherwise be exhausted outside the home, is recovered by the heat exchanger in the ComfoAir unit to temper incoming supply air. To manually increase airflow if needed, TJ’s installed a wall-mounted Zehnder control.
The Federal tax credit’s importance
Since the home’s completion and occupancy last fall, TJ’s reports that the geothermal system has operated as designed and has fully met the client’s expectations. In addition to the concerns about energy efficiency savings and environmental considerations, a driving factor for many of TJ’s geothermal clients is the 30% federal tax credit, a credit that Cutler, and the geothermal industry, would like to see continued beyond 2016.
General Contractor: Parker Construction, East Providence, RI
HVAC: TJ’s Plumbing and Heating, Attleboro, MA
Geothermal Well Driller: Skillings & Sons, Amherst, MA
Interior Designer: Scarborough Phillips Design, West Warwick, RI
Wholesaler: Delta T, Warwick, RI
Bosch Thermotechnology and TJ’s Plumbing and Heating supplied information for this case study. Tim Cutler, owner of TJ’s, is an Accredited Bosch Contractor. He is also IGSHPA and NATE Geo certified.