Field Monitoring of a Variable-Speed Integrated Heat Pump/Water-Heating Appliance.
Field Monitoring of a Variable-Speed Integrated Heat
Pump/Water-Heating Appliance.
(1769 K)
Fanney, A. H.
Paper 3888;
ASHRAE Transactions, Vol. 101, No. 2, 1-15, 1995.
Keywords:
heat pumps; integrated water heating; field study;
building technology; coefficient of performance;
combined performance factor; HSPF; peak demand; SEER;
thermal performance; variable speed; electrical power
Abstract:
A variable-speed integrated heat pump/water heating
appliance was monitored for two years while meeting the
space-conditioning and water-heating needs of an
occupied residence. Experimental results are presented
that show the total energy consumed by the residence was
significantly reduced compared to previous years in
which electric baseboard heat, a wood stove, and window
air conditioners were used. During the two
space-heating seasons, the variable-speed integrated
heat pump/water heating appliance used 60% less energy
than would have been consumed by an electric furnace
with the same air distrubition system and a storage-type
electric water heater. The monthly space-cooling-only
coefficients of performance (COP) ranged from 2.50 to
4.03, whereas the monthly space-heating-only
coefficients of performance ranged from a low of 0.91 to
a high of 3.33. A proposed index to quantify the overall
system performance of integrated
water-heating/space-conditioning appliances, referred to
as the combined performance factor, ranged from 1.55 to
3.50. The majority of larger values occurred during
months in which space cooling dominated. The combined
performance factor for the entire two-year study was
2.45. A conventional watt hour meter supplied by the
local electrical utility and an electronic digital power
analyzer were used to measure the energy consumption of
the variable-speed heat pump to discern if
variable-speed equipment introduces errors in
conventional utility metering equipment. Measurements
made using the two instruments were in excellent
agreement. The monthly energy consumption and peak
electrical demands of the residence, integrated heat
pump/water-heating appliance, supplemental space heater,
and water heater are discussed. The influence of
outdoor temperature on electrical power demand is
presented.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899