GB977673A - Improvements in or relating to flue controls for gas fires - Google Patents

Abstract

977,673. Flue control relating to gas fires. R. & A. MAIN Ltd. Nov. 6, 1963 [Nov. 23, 1962], No. 44473/62. Heading F4W. A gas fire of the type wherein secondary combustion air is drawn to the burners through the fire casing bottom and diluent room air is drawn through further fire casing openings to a space within the casing, both streams flowing to an outlet at the back of the casing, is provided with chamber disposed between the casing and the flue, said chamber having upper and lower openings 18 and 19 communicating with said outlet and space respectively and a valvecontrolled flue outlet 24. The chamber comprises vertical progressively stepped rear walls 15, 16, 17 and side walls 13 attached to the fire casing by flanged edges 14. An upper flue outlet 24 and an additional lower outlet 20 are provided in the upper rear walls, the former being controlled by a flap valve 23 pivoted at 22 between the side walls and biased inwardly open by an attached weight 29. The lower edge of the outlet 24, formed by an arcuate lip 25 struck about the pivot axis, extends horizontal and parallel with the valve edge 28 until as indicated in Fig. 1 (not shown), it terminates in a cut-away inclined section 27. The outlet may be otherwise shaped but still such that the rate of decrease of outlet area decreases with valve closure. The opening 20 may be dispensed with, its equivalent flow area being provided by a clearance between the valve 23 and opening 24. If a heat exchanger is incorporated, the lower opening 19 communicates with room air through an additional opening in the fire casing.