Stimmen - 4, Durchschnittliche Bewertung: 4.8 ( )

Hersteller: Carrier Dateigröße: 993.62 kb Dateiname: 58dp,dr-2si.pdf Unterrichtssprache:

The pilot valve is held open by the “hold” device within gas valve GV. The main valve portion of gas valve GV has a delayed opening operator that opens within 6 to 15 seconds after it is energized, permitting gas flow to the main burners where the gas is ignited by pilot SP. 2. Honeywell VR 800A Gas Valve (Match-Lit Models). See Fig. 11 The furnace pilot must be lit to energize the thermal magnet circuit of gas valve GV, thus permitting gas flow to the remaining portion of the valve. When the thermostat “calls for heat,” the control circuit is closed between terminals R and W. Power from transformer TRAN through fusible linkn FL, limit switch LS & ALS and vent safety shutoff switch VSSS energizes gas valve GV, causing the valve to open and permitting gas flow to the main burners, where it is ignited by the pilot. 3. Blower Circuit With power through the solid-state time-delay circuit on printed-circuit board PCB and heat relay HFR, blower motor MTR is energized on heating speed approximately 75 seconds after gas valve GV has been energized (or the pilot flame has been proven in the case of IID systems). 4. Limit Control If the furnace overheats for any reason, limit control LS switches, breaking the circuit to automatic gas valve GV. The gas valve closes immediately, stopping gas flow to the main burners and the pilot. In addition, flower motor MTR continues to operate because heat relay HFR is deenergized to cool down the furnace. Manual reset auxiliary limit switch ALS is located on the top right-hand corner of the furnace. In the event of blower motor failure, this switch breaks the electrical circuit to the gas valve, stopping gas flow to the main burners. The switch must be manually reset after the blower motor has been replace. Fusible link FL is provided in the transformer TRAN secondary circuit as protection from overheating conditions in the vestibule area of the furnace. Should this condition exist, the fuse opens and deenergizes gas valve GV and heat relay HFR, stopping the gas flow to the burners and starting blower motor MTR. When the thermostat is satisfied, the circuit between R and W is broken, deenergizing automatic gas valve GV, pilot SP (when used), and the solid-state time-delay circuit on printed-circuit board. The gas flow stops immediately to the pilot and main burners with the IID controls, and to the main burners only with standing pilot controls. After approximately 105 seconds, heat relay HFR is energized and blower motor MTR stops. 5. Vent Safety Shut-off System Switch The purpose of this control is to safely shutdown the furnace if a blocked vent condition occurs. During a blocked vent condition, temperature in the drafthood opening will rise causing vent safety shut-off switch to open, breaking the circuit to gas valve GV. The gas valve closes immediately, stopping gas flow to the main burners and pilot, and the blower will run continuously. The furnace will remain in this mode until the vent safety shut-off system switch is manually reset. B. Vent Damper (When Used) With gas and electrical power supplied to the furnace, the vent damper motor is deenergized, and the vent damper is closed until the thermostat “calls for heat.” On a “call for heat” by the thermostat, the vent damper motor is energized and the damper opens. When the vent damper reaches the full-open position, the damper motor is deenergized and a circuit is completed to the main gas valve via the pilot. At this time, the main gas valve is energized and the main burners are ignited; the vent damper will —6— remain open until the thermostat is satisfied. When the thermostat is satisfied, it will deenergize the main gas valve and stop the gas flow. The vent damper motor will energize and close the damper. When the vent damper reaches the full-closed position, the damper motor is deenergized and will remain so until the next “call for heat” by the thermostat. C. Cooling (Cooling Models Only) When the thermostat “calls for cooling,” power from transformer TRAN energizes the condensing unit contactor, cooling relay coil CFR, closing its contacts and energizing blower motor MTR on its cooling speed. It continues to operate until the thermostat is satisfied. When the thermostat is satisfied, the circuit to terminal Gc is broken, deenergizing cooling relay coil CFR which, in turn, opens its contacts, stopping blower motor MTR. VIII. FILTER ARRANGEMENT The two factory-supplied filters are shipped in the blower compartment. After the return-air duct has been connected to the furnace, install the filters in a V-formation inside the retum-air plenum. See Fig. 12. A WARNING Never operate the unit without a filter or with the filter access door removed. A failure to adhere to this warning can cause a fire, physical injury, or death. IX. STARTUP AND ADJUSTMENT In addition to the following information, refer to “Procedures for Natural-Draft Gas-Fired Furnaces” packaged with the unit. NOTE: There is a...

Herunterladen

Geben Sie zwei Ziffern: