CI-81-09-3 -- Single-Zone Computer Model for Residential Furnace Location Analysis

A computer model has been developed to evaluate the effect of the location of fossil-fuel-fired residential central home equipment, such as a furnace or boiler, on its performance. The model is based upon existing computer programs such as DEPAF, DEPAB, NBSLD, and the model in the NBS/DOE Furnace/Boiler Test Procedure. In this model, the dynamic interaction of a furnace (or boiler), a thermostat, and a building envelope is simulated. For a given building structure, the furnace location can be indoors, outdoors, in an indoor closet, in an outdoor closet, in the basement (heated or unheated), or in the crawl space. The model is to be used to determine the fuel consumption for a given furnace in various locations with the same building structure and weather pattern. Currently, the model is limited to a one-zone building interior with a fossil-fuel-fired furnace located either inside or outside of the heated space.

This model is called FLAIR which stands for the first letter of each word in Furnace Location Analysis In Residence. A
room heat balance equation is solved every minute, and the impact of outdoor temperature variation is considered every 30 min. The thermal behavior of a furnace is evaluated every 5 sec. It is necessary to determine room air temperature at least every minute because the supply heat from the furnace varies over a wide range in a short time period. The model requires furnace, thermostat, and building thermal design data as input. The output of the model includes furnace performance, and room conditions.

A mobile home without interior partitions was situated in one of the NBS environmental chambers. The mobile home was heated by an up-flow gas-fired indoor furnace with a single clam-shell heat-exchanger, which was controlled by an anticipator type thermostat. Simulation results are compared with the experimentally measured values and presented in this paper. Details of this experimental work will be presented in a future paper. This paper will concentrate on the computer modeling.

Citation: ASHRAE Transactions, Volume 87, Part 2, Cincinnati, Ohio



Product Code(s): D-CI-81-09-3