Nearly half of the Lennox heat pumps installed in 472 homes in three Fairfax County subdivisions have had major breakdowns during their first five years of use, homeowners have reported.

The Lennox HP8-311 and HP8-411 heat pumps, installed in homes in the Fox Mill Estates, Hunters Creek and Colonial Green subdivision in the Herndon-Reston area, have had compressor failures and assorted other problems, residents said.

Disclosure of the heat pump problems, which one homeowners' association has reported to the Fairfax County Department of Consumer Affairs and the Federal Trade Commission, follows on the heels of the FTC's recent settlement with another major heat pump manufacturer, the Fedders Corp. That company was required to reimburse repair costs incurred by 40,000 heat pump customers -- in a settlement that reportedly may reach $2 million.

Residents of Fox Mill Estates near Reston have been negotiating with the Lennox Corp. for more than two years to be reimbursed for $20,000 the residents say about 60 of them have spent on repairs. They originally paid an extra $1,500 to get the energy-efficient heat pumps installed when they purchased their homes from 1975 on.

An electic heat pump is similar to an air conditioner. In the summer it extacts heat from the interior of a home, transfers it through a heat-absorbing refrigerant which changes into a gas, and passes the heat to the outside, leaving the interior of the home cool. In the winter, the flow of refrigerant is reversed. Heat is absorbed from the outside air and distributed through warm air ducts throughout the home.

In early 1979, Lennox service agents inspected the Fox Mill heat pumps, most of which then were about three years old.Newer optional parts were added to the machines and at least 34 compressors were replaced at no cost to the homeowners, according to resident Maryann Moulton, who has been active in pursuing the matter.

However, she said, half of the compressors that were replaced at that time also failed, costing 17 homeowners a total of about $5,000. In addition, optional switches added were found to be defective and had to be taken off, she said.

Ray Durazo, a spokesman for the Air Conditioning and Refrigeration Institute in Rosslyn, said an eight-to-10-year life span for a compressor is "probably the norm."

Lennox spokesman David Chase said the company has not been able to determine the cause of the failures. The company has lived up to the terms of the five-year warranty on the machines, he said, which provides parts replacement but not labor costs after the first year.

Chase denied reports that problems with their heat pump had surfaced elsewhere in the country, except for "isolated spots" in Ohio and the Baltimore-Washington areas.

The company does not make the HP8-311 and HP8-411 models any longer, Chase said, but that is the result of a "normal evolutionary" process in upgrading the machines. "It's sort of like it would be very hard to buy a 1964 Chevrolet now," he said.

Of the approximately 300 Fox Mill homes with Lennox systems, Moulton said, compressor units in 119 of them have failed since installation and another 25 have had a variety of other problems.

While about half of the units with compressor failures were still under the one-year labor warranty, the remaining homeowners had to meet the labor costs. Parts are provided free for an additional four years. Labor costs for replacing a compressor are about $300, and the compressor itself costs about the same.

Last May company officials offered a $300, three-year service contract providing twice-a-year inspections and repairs at no extra charge to all Fox Mill residents wanting it.

But some homeowners who have had problems with their heat pumps rejected that offer overwhelmingly, saying better service contracts are already available to them from other sources.

Chase suggested that homeowner maintenance may be the source of most of the problems. "A heat pump requires maintenance," he said. "People need to think that way when they buy a house with a heat pump." Filters should be changed frequently, according to servicemen, and twice-yearly service checks should be made by professionals.

A major problem for the homeowners has been pinpointing the causes of the breakdowns: the installation, inadequately sized units for the houses, the machines themselves or poor homeowner maintenance.

Moulton says the 119 affected homeowners in her area do not have the money to conduct costly engineering studies to find out if the system is poorly designed, or the money for litigation.

"They're leading us to a dead end," she said. "They're [Lennox] just buying time until our warranties expire." Moulton and her husband Fred, who live on Viking Drive in Herndon, spent $240 on a new compressor in December 1977, 20 months after they purchased their home for $48,000.

"The thing of it is," said her husband, a salesman for Southern Floors and Acoustics Inc., "we shelled out $1,500 because we thought a heat pump was the only way to go. We don't know if a year from now, we'll have to spend $600 fixing it again."

They also found that when the heat pump failed to function properly, they often did not discover there was a problem until they received unusually high electric bills of about $150. With the heat pump working properly, Maryann Moulton said, the bill would be about $100.

Two residents in the subdivision said they had minor electrical fires in their homes. One owner, Malcolm Kay, an insurance agent who moved into a $56,000 colonial with his family in 1976, is especially embittered by his experiences.

Shortly before Christmas of 1977, the Kays returned home with their Christmas tree. "Our cat was doing the fandango in the basement," Kay recalled, because "the circuit breaker [to the heat pump] was sparking like mad; sparks were shooting 20 to 30 feet into the yard."

He managed to shut the circuit breaker off before anything else caught fire, and he, his wife and their year-old son spent the night in front of the fireplace.

Kay's casualty insurance paid the $1,000 repair fee, which included replacing the compressor, but Kay said he has spent about $450 of his own money getting the system fixed, and has recently been told by a repairman that the second compressor will not last through this winter.

Kay now says he is planning to spend about $2,500 installing a completely new heat pump system. "Why throw good money after bad?" he said.

Fox Mill and Hunters Creek in Herndon were built by the former construction firm of Miller and Smith, whose partners have since split. Colonial Green in Reston was built by Gulf-Reston. But the heatpump systems in Fox Mill and Colonia Green were installed by William H. Metcalfe & Sons. The heat pumps in Hunter Creek were installed by Kraaft, Inc.

Thomas Brown, former president of the Hunter Creek Homes Associations, said he found two years ago that about half of the 100 homes there equipped with Lennox systems had needed repairs since installation. The matter has not been prusued with the company for the last two years, however, he said.

Kenneth Cohen, a board member of the Colonial Green Homeowners Association in Reston, said a March survey he conducted found that at least 29 of the 72 three-year-old homes there equipped with the Lennox systems have had problems, but no organized group action has been taken on the matter.

An FTC spokesman, who asked not to be identified, would not comment on whether that agency is investigating Lennox. Although heat pumps have been on the market since the 1950s, they started selling in greater volume since the energy shortage in 1973, and more problems have been reported since then, he said.

At any rate, even if the FTC is investigating the situation, any action taken would not be for some time, the FTC spokesman said.

Tony Provine, superivsor of investigations with the Fairfax Comsumer Office, commented, "I don't think the picture looks very good at this point" for the homeowners.

The case "doesn't seem to come under the Virginia Consumer Protection Act." which outlaws false claims made for products, he said. None of the homeowners interviewed had purchased theirs independently since the units came with the houses, and were therefore not responding to any particular claim.

And in any case, most of the heat pumps were purchased before the act went into effect in July 1977, he noted.

"The equipment was sold at a time when the energy crunch first hit and everyone was groping for a solution," Kay said. "We were basically the experiment."