Washington Gas Light Co. has proposed detailed plans involving the use of computers, meter readers and servicemen to detect and charge higher rates to customers who use electric heat pumps to cut gas consumption significantly.

The idea, as outlined by the utility's officials, is not to raise rates for customers using marginal energy-saving devices -- such as wood stoves -- but to discover those customers who do succeed in significantly cutting their use of gas for energy. The company serves 545,000 customers in the Washington area.

Rates would also be raised for some marginal energy-saving experiments, Washington Gas Light Vice President Edmund Smallwood said in an interview yesterday. He said the rates would go up if the experiments "make ags a secondary energy source with no substantial [overall] energy saving...."

The company's rationale is that customers who use gas only on a standby basis continue to cost the company the same amount as ever in fixed capital costs while significantly cutting WGL revenues.

The utility filed documents with the Maryland Public Service Commission on Friday in connection with its request to increase rates for customers who cut gas consumpiton. The documents say that the request is not now aimed at the use of such devices as wood stoves, solar devices or "experimental applications" of such things as wind power and waste heat recovery.

In the documents, WGL asked the commission to require that customers notify the utility when they install heat pumps. If the company's request is granted, Smallwood said, the utility will ask its servicemen and gas meter readers to check the homes they visit to see if customers have installed electric heat pumps in conjunction with their gas furnaces without telling the company.

Smallwood said in his testimony and in yesterday's telephone interview that the new rates would not be applied to customers who conserve energy by turning down their termostats or even by substituting another energy source as a supplement to gas heat. It is when that supplement becomes a major heat source that WGL has problems, Smallwood said.

In the documents, Smallwood said the company will ask its servicemen and gas meter readers to check the homes they visit to see if customers have installed electric heat pumps in conjunction with their gas furnaces and without telling the company.

If this is the case, Smallwood said, the customers would be charged the higher "standby rates" that WGL is applying for in Maryland, Virginia and the District of Columbia. WGL servicemen make about 253,000 visits to homes each year, Smallwood said.

He also said the company is developing a sophisticated computer program to catch people who have installed heat pumps without telling WGL. The program would "trace unique load patterns such as might be expected with the use of a heat pump as the primary heating equipment," according to Smallwood's testimony.

The company's application in Maryland asks that customers be required to seek Washington Gas Light's approval before experimenting with alternate energy sources -- like wind, waste heat recovery or "biomass" (example: burning trash for heat).

Smallwood said yesterday that, in most cases, WGL would grant approval. But, he said, "we want to be kept apprised and we might put in some meters (to monitor the experiment)."

The requested rate change would not affect customer use of appliances such as gas water heaters and gas ranges.

Smallwood also testified that Washington Gas Light might check building permits on file in local jurisdictions to see if people had obtained permits to install heat pumps.

Solar devices would be excluded from the new, higher rates that WGL has asked for because they represent a real energy saving. Sunlight is free, and in addition WGL thinks it will be years before solar technology poses a real threat to gas consumption.

The company has not aimed its attack at wood wtoves, according to Smallwood, because wood is not considered a significant threat to gas consumption.

House are not designed to use wood heat efficiently, he said. "Right now, unless a cord of wood could supply the heating requirements for a month, wood would have a difficult time competing economically wiht gas." Wood now costs about $65 a cord, he said.

But Smallwood said yesterday that if people "in large numbers" begin to cut gas consumption by using wood as a "primary energy source," then WGL would apply for permission to charge them higher rates for the gas they used.

The company argues that electric heat pumps used in conjunction with gas heat as a backup for particularly cold days represent no overall saving in energy.

Consumer advocates and the heat pump industry disagree with this contention. The U.S. Department of Energy has said it will intervene in the case because WGL's proposed rates may discourage conservation and discriminate against people who switch to alternate energy sources.

Heat pump manufacturers like General Electric say sales have boomed in recent years, and they see WGL's proposed rates as an effort to preempt their market. It is not known if many people have yet installed heat pumps in conjunction with gas, although this is an option that the manufacturers recently have started to encourage.

According to Smallwood and the documents filed Friday, customers who use gas on a standby basis in Maryland would be charged a $16.39 monthly service charge. Regular customers would pay an $8.40 service charge under WGL's recently granted 2.41 percent rate increase in the state.

Both standby and regular customers would pay the sme "commodity charge" of 26 cents per therm -- a measure of gas.

The company's application in Maryland asks that customers be required to seek WGL's approval before experimenting with alternate energy sources -- such as wind, waste heat recovery or "biomass" (Example: burning trash for heat).

Smallwood said yesterday that in most cases WGL would grant approval. But, he said, "we want to be kept apprised and we might put in some meters (to monitor the experiment)."

He said if the experiment were successful in relegating gas usage to a secondary role, then the standby rate would automatically be charged.