This paper describes a unique research program being undertaken by a U.S. manufacturer and the French national utility, Electricite De France (E.D.F.).

Impetus for this research was provided by the aggressive E.D.F. nuclear power generation program and interest in reduced dependency on imported oil. Since the majority of French homes are heated with oil-or gas-fired hydronic systems, air-to-water heat pumps are of interest, applied in a bi-valent, or dual-fuel system. With such systems the heat pump provides heat to the home, through a circulating water and radiator system, at outdoor temperatures above freezing. At lower outdoor temperatures, the boiler, or boiler and heat pump, provides the heating. Air conditioning in French residences is uncommon except in southern France, so that heating-only heat pumps are of primary interest for the existing homes.

Thus electric heat pumps can, potentially, offer an attractive residential heating system in France. Similarly, there is growing interest in such systems in areas of the U.S. where hydronic heating systems have traditionally been popular (Northeast, Central and Northwestern regions).

These bi-valent air-to-water heat pump installations can be complex and expensive, however, so it is of interest to investigate aspects of systems design and performance, and to assess the energy-saving benefits which will accrue to the homeowner. E.D.F. was also interested in the impact of the heat pump systems on the utility, and the expected operating patterns which may occur under alternate electric tariffs. A number of technical and application questions are being addressed, as well, including sizing, whether acceptable heating performance can be obtained with the hydronic systems at reduced system water temperature levels, opportunities for improved air-to-water heat pumps designs, and performance comparisons with other heating system approaches.

One of the most important tasks in this program involved monitoring of a bi-valent air-to-water heat pump installation to provide actual operating data to characterize state-of-the-art design and performance of these units. An air-to-air heat pump and an oil-fired boiler system were also monitored in this program for comparison purposes. All three systems are installed in residences located in the Paris, France area.

Special instrumentation, developed and utilized on other heat pump monitoring programs in the U.S. is used to collect data on all important equipment and system operating parameters, including installed heat pump efficiency.

The monitoring program has covered two heating seasons, 1980-81 and 1981-82. This approach enabled several changes in the systems to be made, based on the results obtained during the first season. Results have been rationalized and extended through use of a special dynamic computer simulation model developed for this purpose.