NATE - Gas & Heat 139 Questions with Complete Solutions 3/8 to 1/2 inch of the end of the thermocouple: - Correct Answer Should be enveloped by the pilot flame A "cross break" made on all sides of any rectangular section of metal duct will: - Correct Answer Increase rigidity and reduced vibration A control string is defined as two or more switch contacts connected in a circuit, or set of circuits, to control a load. In order to troubleshoot a load controlled by a control string, the technician must first: - Correct Answer Check for proper voltage applied across the load A customer complains the unit is "blowing cold air". The technician determines that the problem occurs at the end of the heating sequence. The furnace used an electronic integrated blower control. - Correct Answer The likely problem with the system is the blower off delay is set too long.A customer has concerns about CO in their home. Many of their reported symptoms indicate there may indeed be a CO problem but on each trip the technician makes to check their home the technician finds normal CO levels. - Correct Answer CO detector reader/recorder would be appropriate to use for determining if a problem truly exists.A damaged section of double wall vent pipe is to be replaced with a section produced by a different manufacturer: - Correct Answer The installer should check the new section for compatible locking joints A dirty or clogged air filter in an operating gas furnace can cause an: - Correct Answer Increase temperature rise A furnace is inoperative because of a failure in the ignition sequence at the flame proving stage. To check the flame proving circuit the technician would: - Correct Answer Connect a microampmeter set to DC microamps in the sensor circuit and operate the furnace.A gas clothes dryer can interfere with the operation of a nearby natural draft gas furnace with an atmospheric burner by: - Correct Answer Stealing combustion air preventing complete fuel burning 1 / 2
A gas furnace should reach a steady state: - Correct Answer Before taking a combustion test A gas furnace with a standing pilot uses a flame switch for proving pilot flame: - Correct Answer Several millivolts are generated by the flame A line voltage fuse is sized to protect from: - Correct Answer Excessive voltage A meter reading microfarads is used to: - Correct Answer Check a run capacitor with a capacitance tester A packaged unit in a two story installation is to be located at ground level with ductwork running up the outside wall to a chase in the second floor. - Correct Answer The precautions need to be taken with outside ductwork is it must be insulated and weatherproofed.A standing pilot furnace uses a relay for controlling the supply blower. On a call for heat, the burner lights, the fan control closes, but the blower does not run. A check of voltage at the blower relay coil shows 24V. The load side measures 0V. The technician should replace what: - Correct Answer Fan relay A system airflow check determines that supply static is 0.15 in. W.C. And return static is a -0.55 in. W.C.These readings tell the technician: - Correct Answer The difference between supply static and return static is unacceptably low.A system that is oversized for the load: - Correct Answer Will cause the unit to short cycle A technician measures the return air temperature of a 100,000 BTU output gas furnace to be 65 degrees and the supply side air temperature is 135 degrees: - Correct Answer The CFM would be 1323 A technician receives a call that a gas furnace is running constantly in heating and cannot be shut off.While checking the thermostat, the technician observes the burner shuts off by removing the wire on the R terminal on the thermostat subbase. - Correct Answer Most likely there is a short in the thermostat subbase
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