Radiant floor job uses DX heat pump system
Special to CONTRACTOR
MONTROSE, COLO. — Colorado homeowner Joe Patterson has enjoyed the comfort of radiant floor heating in his home for six years.
“Radiant floor is the best!” Patterson says. “It’s always comfortable and warm on your feet during the winter.”
But just eight months ago, he also began to benefit from significant savings when he replaced his gas-fired boiler with a direct-exchange geothermal system for radiant heat and domestic hot water.
Patterson’s system uses a direct exchange geothermal heat pump manufactured by ECR Technologies and sold under the trade name EarthLinked. It has five 100-ft. loops of refrigerant tubing buried in the ground to transfer energy to the heat pump. The system uses R-22 refrigerant.
Today, Patterson’s monthly gas bills are only $8, which is $200 less than he had with his previous system. His monthly electric bills have risen only about $20. Overall, the system saves the Patterson family about $180 per month.
As part owner of drilling equipment manufacturer TEI Rock Drills, Patterson has developed an interest in geothermal heating and cooling technology. When he heard about the system, he decided to try it in his own home.
The Patterson home, located in Montrose, is a ranch-style house with three bedrooms and 2,200 sq. ft. of living space. TEI Rock Drills and Montrose contractor Snipps HVAC successfully installed a 5-ton, diagonal-loop unit in just two days. The system heats water for the radiant floor loops and preheats water for the water heater.
When comparing this system to other geothermal possibilities, Patterson found that a DX system costs half as much to install because it requires less drilling than water-based geothermal systems need. While other geothermal systems rely on plastic piping to circulate water and antifreeze through a large, intermediate loop, a DX system circulates refrigerant through highly conductive copper earth loops, enabling a direct transfer of thermal energy from the earth.
Patterson’s interest in the system is professional as much as personal. Because he manufactures equipment for rock drilling, he had to try it himself.
“It looked like a market for a lot of drills,” he said.
He’s pitching the idea to other rock drillers and trying to hook them up with HVAC contractors, he said, “because drilling contractors don’t know how to hook up a system and HVAC contractors make terrible drillers.”
Patterson took home a Bobcat mini-excavator with the drill rig attached over a weekend. Starting from a 5-ft.-by-5-ft.-by-3-ft. deep pit near the house, he drilled the five 100-ft. long holes at a 30° angle.
The refrigerant pipe was snaked into the holes and backfilled with a grout called Mix 111, which is a thermally enhanced grout that can stand the temperature fluctuations created by the refrigerant, said Shane Mitchell of Snipps HVAC.
Mitchell hooked the refrigerant tubing to a manifold inside the pit. The connection from the manifold to the heat pump is much like a conventional refrigerant line set. The water is heated through a tube-in-tube refrigerant-to-water heat exchanger. The hot water feeds into a storage tank that’s a buffer between the heat pump and the radiant floor.
Mitchell hooked into the distribution system previously used for the boiler, which he said is a simple thermostatically controlled system that opens and closes zone valves in the loops and runs a circulator connected to the storage tank.
Mitchell said the installation, his first, took perhaps twice as long as it should have, but he’s since done others. He’s pursuing other projects using the DX system.