Fireplace Pilots Take Gas Use Sky High

The field trial found that consumer behavior was key to energy savings with gas fireplaces. Fireplaces, such as this one, with easy-to-reach pilot lights could significantly improve overall energy efficiency.

The average gas fireplace pilot uses about 21 ft3 (0.6 m3) of gas per day. In the past, manufacturers have claimed that people turn off pilot lights between uses. If this were the case, many gas fireplaces would be quite efficient. Some could significantly reduce overall household gas use in houses with gas furnaces. On the other hand, if the pilot is left on all year, it will use about 7.3 therms of gas, making the overall efficiency of the fireplace much lower and increasing gas consumption.

To get a sense of how the fireplaces were actually used, we carried out a detailed field trial, closely monitoring 68 homes with gas fireplaces and furnaces for an entire year. Data loggers digitally measured and recorded furnace and fireplace gas consumption every 15 minutes, and weather data every hour.

Once the logging was done, we analyzed the results. We found that 16 of the gas fireplaces had insignificant use: they were fired up fewer than six times per year. In the 52 homes with significant use, 14 gas fireplaces either did not have a continuous pilot or had one that was shut off daily during the heating season.

We also monitored pilot use in the summer. Of the 38 homes where fireplace use was significant and the pilot light was on continuously during the heating season, only 8 turned the pilot off for the summer. In the 30 where the pilot light was on all year, the pilot accounted for half (48%) of the total gas fireplace fuel consumption. On average, these fireplaces used 31% as much gas as the homes' central gas furnaces.

For the 14 homes where fireplace use was significant but the pilot light was not left burning all the time, the average yearly gas consumption was only 6.7 therms. This yearly consumption was lower than pilot light consumption alone in the other 38 homes. These 14 fireplaces used only 8% as much gas as their homes' central furnaces. In these homes, fireplace use correlated closely with outside temperature. Fireplaces without continuous pilots were far more effective than continuous-pilot units at reducing overall house gas consumption.

The 16 homes in which the fireplace was almost never used were particularly interesting. Only 5 of these homes shut their pilot light off at all. For the other 11, the pilot was on continuously for the entire year, using over 7 therms of gas for no household heat.

There are two options for efficient pilot light operation in gas fireplaces. The first and most obvious is to buy a unit that does not have a continuous pilot light, but rather some sort of intermittent ignition, like those on all gas furnaces sold today. However, some fireplace manufacturers are concerned about the safety and reliability of these devices, in spite of their widespread use on other equipment. Many homeowners also want to have the gas fireplace as a source of heat that is independent of electricity in the event of a power failure, and a continuous pilot light helps to meet that objective.

The second option, then, is to buy a unit with a continuous pilot, but one on which the pilot light shutoff and relight controls are easy to access and use. Turn off the pilot light whenever the fireplace is not being used.

This research was conducted for the Canadian Gas Association, which recently developed a seasonal efficiency test procedure for gas fireplaces. This test measures fireplace performance under real-world conditions. The report, Analysis of Gas Fireplace Usage from Real Homes, is available from A.C.S. Hayden, Advanced Combustion Technologies, ETB/CETC, 580 Booth St., Ottawa, Ontario, Canada K1A 0E4. E-mail: skip.hayden@cc2smtp.nrcan.gc.ca.
 

A.C.S. Skip Hayden is a senior research scientist at Advanced Combustion Technologies of CANMET in Ottawa, Canada.

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