NATE GAS HEAT PRACTICE GUIDE
Questions and Answers
1.What precautions are required when mounting any gas
furnace on a wood platform in an attic?
ANS None
2.The gas control valve may be damaged if exposed to an inlet
pressure above what?
ANS 14 inch W.C.
3.How many elbows and joints should a vent connector
have?
ANS As few as possible to reduce resistance of flue gases.
4.Under what conditions, if any may the technician route the
exhaust of the furnace into the exhaust vent of the water
heater
ANS Under no conditions may you use the water heater exhaust vent.
5.How may a technician terminate the intake and exhaust for
proper operation of a high efficiency gas furnace when using
scheduled 40 PVC pipe
,ANS By using the specific manufacturers termination kit or make one to
meet their requirements.
6.When suspended with metal strap and no saddle, flexible
duct should be
ANS supported with a minimum strap width of
1/2".
7.A technician is installing a gas furnace and the customer has
decided not to install an air conditioner. Making this decision,
the affect it will have on the installation of the supply ductwork
is
ANS Leave adequate space should be allowed for addition of a coil in
the future when feasible.
8.Leveling of a Mercury bulb is
ANS Critical
9.Spray-type atomizing humidifiers are installed to do what?
ANS Discharge mois- ture into the supply duct.
10.Electronic air cleaners (EAC) installed in a gas furnace
system should be wired so they
ANS Only operate any time the EAC On-Off switch is turned to ON.
,11.The LP gas manifold pressure is commonly what?
ANS 10 to 11 in. W.C.
12.The polarity of a 120V gas furnace equipped with electronic
flame rectifi- cation is important because
ANS The ignition control may not prove flame.
13.Using a voltmeter, a technician can determine voltage drop
at a gas fur- nace
ANS With the furnace not operating and then with the furnace
operating.
14.The setting on a 4 speed PSC blower motor can be changed
by changing the
ANS Motor tap connection.
15.When starting up a dual system, the temperature rise
method for de- termining airflow cannot be used with
compressor cycle of the heat pump because
ANS The capacity of the system varies too much with outdoor
temperature.
16.The flame pattern a technician would expect to see on a
properly operating single stage gas furnace equipped with "in
shot" type burner is a
, ANS Hard and forceful flame with a light blue appearance and little or
no yellow.
17.What is recommended method for a pressurization leak test
of a fuel gas pipe?
ANS Compressed air
18.What is a diaphragm type differential pressure gauge used
for?
ANS Measure air pressure.
19.The pressure reading on a manometer is expressed in
ANS Inches of water.
20.A technician measures the return air temperature of a
100,000 BTU output gas furnace to be 65°F and the supply side
air temperature is 135°F. Calculate the CFM.
ANS The CFM would be 1323.
21.A dirty or clogged air filter in an operating gas furnace can
cause what?
ANS -
Increase temperature rise.
Questions and Answers
1.What precautions are required when mounting any gas
furnace on a wood platform in an attic?
ANS None
2.The gas control valve may be damaged if exposed to an inlet
pressure above what?
ANS 14 inch W.C.
3.How many elbows and joints should a vent connector
have?
ANS As few as possible to reduce resistance of flue gases.
4.Under what conditions, if any may the technician route the
exhaust of the furnace into the exhaust vent of the water
heater
ANS Under no conditions may you use the water heater exhaust vent.
5.How may a technician terminate the intake and exhaust for
proper operation of a high efficiency gas furnace when using
scheduled 40 PVC pipe
,ANS By using the specific manufacturers termination kit or make one to
meet their requirements.
6.When suspended with metal strap and no saddle, flexible
duct should be
ANS supported with a minimum strap width of
1/2".
7.A technician is installing a gas furnace and the customer has
decided not to install an air conditioner. Making this decision,
the affect it will have on the installation of the supply ductwork
is
ANS Leave adequate space should be allowed for addition of a coil in
the future when feasible.
8.Leveling of a Mercury bulb is
ANS Critical
9.Spray-type atomizing humidifiers are installed to do what?
ANS Discharge mois- ture into the supply duct.
10.Electronic air cleaners (EAC) installed in a gas furnace
system should be wired so they
ANS Only operate any time the EAC On-Off switch is turned to ON.
,11.The LP gas manifold pressure is commonly what?
ANS 10 to 11 in. W.C.
12.The polarity of a 120V gas furnace equipped with electronic
flame rectifi- cation is important because
ANS The ignition control may not prove flame.
13.Using a voltmeter, a technician can determine voltage drop
at a gas fur- nace
ANS With the furnace not operating and then with the furnace
operating.
14.The setting on a 4 speed PSC blower motor can be changed
by changing the
ANS Motor tap connection.
15.When starting up a dual system, the temperature rise
method for de- termining airflow cannot be used with
compressor cycle of the heat pump because
ANS The capacity of the system varies too much with outdoor
temperature.
16.The flame pattern a technician would expect to see on a
properly operating single stage gas furnace equipped with "in
shot" type burner is a
, ANS Hard and forceful flame with a light blue appearance and little or
no yellow.
17.What is recommended method for a pressurization leak test
of a fuel gas pipe?
ANS Compressed air
18.What is a diaphragm type differential pressure gauge used
for?
ANS Measure air pressure.
19.The pressure reading on a manometer is expressed in
ANS Inches of water.
20.A technician measures the return air temperature of a
100,000 BTU output gas furnace to be 65°F and the supply side
air temperature is 135°F. Calculate the CFM.
ANS The CFM would be 1323.
21.A dirty or clogged air filter in an operating gas furnace can
cause what?
ANS -
Increase temperature rise.
