BY ROBERT P. MADER Of CONTRACTOR’s staff
HARTFORD, CONN. — Geothermal heat pumps and radiant floor heat make a great combination, especially at the relatively low temperatures that radiant requires, said Jeff Persons, president of Geo Source One Inc., Plain City, Ohio.
Persons addressed contractors meeting here at the Radiant Panel Association’s Radiant Expo in late August.
Persons noted that he’s been in the business since the 1970s and has heard many discouraging energy price forecasts over the years. None of them, however, he noted, figured a booming Chinese economy into the mix. Natural gas in his region of Ohio has increased by 240% over the last seven years to $1.60 per hundred cubic feet.
The country’s natural gas supply is so shaky that commercial/ industrial users were notified after Hurricane Katrina that they were in imminent danger of having their gas supply temporarily shut off, Persons said.
Geothermal heat pumps can provide part of the solution, Persons said, by reducing fossil fuel consumption by 80%. They can save 80% for heating because they have a Coefficient of Performance of 500%, 60% for air conditioning with an Energy Efficiency Ratio of 30.0, handle 60% of domestic hot water needs and, in some installations, 100% of DHW with the use of a storage tank.
In summer rejected heat is stored in the ground for the following winter and in winter the ground is chilled by spring just in time for the cooling season.
The systems use a minimal amount of electricity to run the compressor and circulators and use R-410a, which is 25% more efficient than R-22.
The systems are extremely efficient operating at 120°F or lower, he noted. Much of the hardware is Energy Star rated.
Persons showed the contractors some of the projects on which his firm has worked.
In Pataskala, Ohio, Geo Source One installed a 5.5 ton Waterfurnace Synergy geothermal heat pump with seven zones of radiant and four zones of air conditioning. The tubing was laid in Warmboard radiant heat subfloor. The 6,850- sq.ft- house used six 150-ft. vertical wells with 3/4-in. fusion-welded polyethylene tubing piped into a reverse return header. The basement is insulated with blue board and uses 1/2-in. PEX tubing. He controlled the bamboo-floored main floor at 115°F maximum, even at design temperatures. The large walk-in shower sports PEX tubing on 4-6-in. centers.
Persons likes to use a stainless steel buffer tank in his installations, and uses it in a variety of ways. The geothermal heat pump heats the water in the tank. The tank has an internal coil to preheat incoming domestic water before it goes to the gas-fired water heater. If the power fails, the 5,500W backup generator will run the water heater, which will pump in reverse to the buffer tank, in effect acting as a backup “boiler” to heat the house.
He can run the floor loops either directly from the heat pump or through the buffer tank. The tank has connection ports or 1- or 1½-in. for low pressure drops and 2-in. of insulation, which makes it good for holding chilled water for air conditioning.
Persons likes to use a Ranco temperature control, which he’s found to be simple and reliable.
Persons installed one of those trophy jobs, 18.5 tons of radiant and forced air in a 12,000-sq.ft. house in Hilliard, Ohio. He used three geothermal heat pumps on the job, which features an all-glass conservatory. He installed PEX on 6-in. centers in the conservatory over 2-in. of Warmboard, and the system is backed up by two 2-ton ductless fan coil units that use geothermal hot water heating and chilled water for air conditioning.
In Ohio, Persons said he needs about 150-ft. of well per 12,000 Btuh. Wells would need to be drilled deeper than that if an installation has an unbalanced load – needing a lot more heating than cooling or vice versa. He can do a small house with a high efficiency system for $12,000, he said, including the equipment and one well.
A 3,000-sq.ft. house requiring 4- tons, Persons said, would cost $21,000- $24,000. He wants to bury 600-ft. of tubing per ton.
He has installed jobs that used fan coils only for heating and cooling and he’s also installed air conditioning that only uses well water, if the water is 55°F or colder; 50°F is better.