News and Events


INTRODUCING THE MOST EFFICIENT AIR SOURCE HEAT PUMP EVER MADE

E Source Tech News, 05/31/02, Volume 3, Issue 5
Cold Climate Heat Pump Set to Debut
Story Date: 05/31/2002

Air-to-air heat pumps have never been a big hit in cold climates. Even at moderate outdoor temperatures, occupants of rooms warmed by heat pumps often complain about discomfort, leading to the use of expensive resistance heating. But the days of the electric heat pump cold weather blues could be over if a new product line performs as well as its developers hope. In July of this year, Nyle Specialty Products LLC plans to introduce a heat pump designed specifically for cold climates. The new air-to-air heat pump is optimized for heating, and tests have shown a coefficient of performance (COP) of 2 at zero degrees Fahrenheit (F) and 2.4 at 10 degrees F. Conventional air-to-air heat pumps would have long since switched to resistance heating at those outside temperatures. You won't need to worry if you're in an area with hot summers‹cooling performance is estimated at a seasonal energy efficiency ratio (SEER) of 16. For comparison, a heat pump
can earn an EnergyStar label with a SEER of 12 or better.

The company will be offering models sized at 2.5, 3.0, 3.5, 4.0, and 4.5 tons. Air-to-water models for use in radiant floor heating will also be offered. The new design enhances performance with a two-capacity primary compressor, a booster compressor, a subcooling circuit, and a sophisticated control system that allows four levels of heating and two levels of cooling. In heating mode, as the ambient temperature drops, the system delivers an increasing amount of heat just the opposite of a conventional heat pump, which delivers less heat the colder it gets. Feedback from an outdoor temperature sensor tells the microprocessor-based controller at what level to set the output. The booster compressor comes on when temperatures drop below 35 degrees F. The control system (based on Johnson Controls' Metasys system) "learns," from its particular environment, which is the best
strategy for modulating output as outside temperature changes. If the indoor temperature continues to fall at a particular setting at a given outdoor temperature, the system will remember that and go to a higher setting next time. Over time the control system learns the settings that will provide comfort with the least amount of energy. Sensors on the coils also help the system run a very efficient defrost cycle. The system does include backup resistance heating, but it only comes on when temperatures fall below zero.

Much of the development of the system was spearheaded by engineer David Shaw of Shaw Engineering Associates. Shaw, who spent a large part of his career designing and developing compressors for the HVAC industry, was motivated to develop the design after moving into a condominium heated by a conventional heat pump. "There's got to be a better way," he thought at the time. As he developed that better way, Shaw received a number of patents on such items as the controlled use of the booster compressor and the variable-capacity control scheme.

The added components will increase the cost of the heat pump by about $800 to $1,000 over a conventional air-to-air unit, according to Nyles' general manager Geoffrey Clarke. However, the installed cost should still be less than the cost of installing a gas or oil furnace and electric air-conditioning system, making Shaw's system very competitive for heating and cooling in new construction. The price should also be competitive with that of geothermal heat pumps, according to Steve Konstantino, president of Enerkon Corp., which is setting up a national distribution network for the heat pumps. He reports that the price of the heat pump will be about the same as the cost for a geothermal heat pump‹not counting any of the digging and installation costs associated with the in-ground solution. Performance of the new product should also be similar to that of a geothermal device, he adds.

To demonstrate those performance claims, field testing of the heat pumps is currently under way at a number of locations, including several installations made under the auspices of Connecticut Light & Power Co. (CL&P), an affiliate of Northeast Utilities. CL&P funded the installation of four units in homes through the Conservation Fund, a public benefits charge fund that it administers. The units were installed late in the recent mild winter, so it will be a year before meaningful cold weather data is available. We'll be following up when we know what the test results are.

For more information, contact:

Nyle Specialty Products LLC
P.O. Box 1107
Bangor, ME 04402
800-777-6953

© 2002 Nyle Special Products, LLC. All rights reserved.