Patent GB-1117712-A (GB)
Title: Improvements in or relating to fuel-fired heaters
IPC: F24D5/08
Filed: 1965-10-08
Abstract: 1,117,712. Burners. HUPP CORPORATION. 8 Oct., 1965 [23 Oct., 1964], No. 42732/ 65. Headings F4F and F4T. [Also in Division F1] A gas-fired infra-red heater comprises a U-shaped aluminium casing 52 divided by a transverse partition (58), into a blower and control compartment and a burner compartment. The burner comprises a tubular line burner 66 extending the length of the burner compartment and two trough-like radiant grids (67) 68 mounted in end to end relationship on the burner 66 and defining therewith a combustion zone 86. A conduit (82) supplies a gas/air mixture from the blower compartment to one end of the burner 66 and the mixture discharges through ports 84 in the lower side of the burner. The heat radiated by the grids (67) 68 is directed into a beam by two semi-parabolic reflectors 92, 94 which extend the length of the burner compartment and are secured to the casing 52 in spaced relationship by screws 102. Combustion products flow through apertures 90 in the grids 67, 68 and through spaces 108 between the burner and the reflectors to a flue collar 110 in the upper wall of the casing 52. Air passes up the spaces 104 between the reflectors 92, 94 and the side walls of the casing to dilute and cool the combustion gases. A baffle 120 directs the combustion gases laterally into the cooling air. The flue collar 110 is provided with a rain cover 116. Heat shields (134, 136, 138) are mounted in the burner compartment in spaced relation to the ends of the burner compartment. The burner control apparatus is mounted on a tray (192), Fig. 1 (not shown), in the blowercontrol compartment and includes a solenoid valve (V), Fig. 3 (not shown), controlling the gas supply to a mixing chamber and energized from a power source (180) through a centrifugal switch (CS) which closes when the motor (M) driving the blower attains a certain speed. The centrifugal switch also energizes a relay (RC) which energizes a spark transformer (T) and short circuits a resistance (X) in the lead to the solenoid valve (V) so that the valve opens. A flame detector comprising a mercury filled capillary tube (CT) located close to the radiant grid (67) opens a switch (FS) in the relay circuit in the presence of a flame to de-energize the spark transformer (T) and to reduce the current through the solenoid valve (V) If the flame is not detected after a predetermined time a heater in the relay circuit causes a bi-metallic switch (BS) to de-energize the solenoid valve and the spark transformer. In a second embodiment, Figs. 4-14 (not shown) the heater includes two side by side distribution tubes (246) of diamond shaped cross-section having two parallel longitudinal flanges (262) forming an outlet passage (264) in which are clamped embossed metallic ribbons (266) forming small outlet passages. The ends of the ribbons are brazed together and project beyond the ends of the distribution tube. Each distribution tube is provided with two in-line infra-red generating grids which are heated by the flames to incandescence and which are formed by displacing loops (292) (Fig. 13) from a sheet of heat resistant metal which is then bent into a horse shoe configuration having mounting flanges (290) extending towards each other. Metal clips (298) engage the flanges (290) and are clamped to the flanges (262) of the distribution tube. The end covers (216, 218), (Figs. 5, 7), of the heater casing (206) are pivoted to the U-shaped main cover member (214) to facilitate replacement of the infrared generators and to provide easy access to the blower-control compartment (224). A pair of inclined reflectors (346), (Fig. 4) is clamped to the flanges (262) of each distribution tube. A U-shaped rain cover covering a flue collar (378), (Fig. 6) in the top of the heater casing may be provided with an aperture into which a flue pipe is connected and a circular baffle (398) is suspended below the aperture. The mouth of the heater casing (206) is covered by an aluminium grill (424), (Fig. 4) of egg-crate construction. Gas is supplied to a mixing chamber (436), (Fig. 8) by a manifold (472) located within the chamber and provided with two spuds (476) screwed to oppositely directed outlets. The air delivered by the blower 430, through an apertured plate (462) to the mixing chamber is automatically controlled by a pivoted damper (500) located in the blower outlet and actuated by a bimetal actuator (508), (Fig. 9) mounted inside the heater casing. As the temperature inside the heater increases the damper opens. The capillary flame detector (582), (Fig. 11) is mounted in parallel spaced relationship to the lower edge of one of the infra-red generators and the loops 292 of the generator above the detector are removed so that the detector responds rapidly to the beginning and termination of combustion. A trough shaped shield (592) shields the detector from drafts. In a third embodiment, (Figs. 17, 18), the reflectors 702 are of apertured construction and are removably mounted and the open bottom of the blower-control compartment is covered by an apertured plate. A spark plug, (Figs. 15, 16) comprises a rod shaped energized electrode (532) and a hairpin shaped grounded electrode (552) mounted on a cylindrical ceramic body (536) so that the rod electrode extends along the axis of the hairpin electrode and a spark gap (570) is formed between the end of the rod and the bend of the hairpin.