furnace

Reports the results of an experimental assessment of the effect of a chimney on the air leakage characteristic of an unoccupied two-storey detached house heated by either gas or electric furnace. Measurements were taken of air tightness values and air infiltration rates with the chimney capped anduncapped.

Discusses five different models for predicting air infiltration. Presents a new model developed at the Institute of Gas Technology. The model is based on the results of tests to obtain the contribution of the existence of a chimney, and furnace operation, to house air infiltration. Reports verification of model by simulating results from 23 test homes. Concludes that model simulates with reasonable accuracy the measured values for a single-storey home equipped with an oil-fired central furnace.

Presents examples of the use of a generalized model of air infiltration, developed earlier, to estimate the air infiltration characteristics of two test homes using data for the structures, weather and furnace installation. One of these is a single-storey home with basement of wood- frame construction, equipped with an oil-fired central heating furnace.

Reports recent studies showing that seasonal efficiency of oil-fired residential heating systems is in the range 55-75% compared with steady-state efficiency of 80% or more. Finds this is due to effect of off-period draughts and of excess combustion air and draught control air on the infiltration loss for the structure. Discusses ways of improving efficiency. Finds sealed combustion systems may offer operating cost savings.

Ventilation rates in two test home were measured using helium as a tracer gas. Pressure differences across the exterior walls of the house were recorded using pressure taps. Gives results for air infiltration tests and the calculated air infiltration. Finds that during summer air infiltration rates varied approximately linearly with wind velocity. During the winter, the pattern and extent of air infiltration were influenced by both house stack action and furnace operation.