Troubleshooting Commercial HVAC Equipment 4th year ILM 110405b Flashcards
What is the final step that needs to be performed to an HVAC system, meeting the design
and/or engineer’s intent?*
________________________________________________________________________
Start-up
What could possibly happen if the equipment is not started up properly?
__________
Failure to properly start-up equipment may void the manufacturer’s warranty
Why is it important to document the date of start-up on the equipment?
____________________
Because that’s the date that the warranty will begin.
When performing a start-up for a RTU, what should be done to allow the crankcase heater
in the compressor to operate properly?
_________________________________
It is recommended that compressors should not be started unless the crankcase heater has been energized for a period of at least 12 hours immediately prior to start-up
According to the regulations, who is able to change orifices in an appliance when
required?
_____________________
A qualified technician who holds a gas ticket
Why is it important to ensure the gas supply pressure is between 5 ½”-13” w.c., and also
not drop more than the 1” w.c. during operation of appliances?*
_____________________
What literature should be provided to the building maintenance personnel?
System’s manual that show’s maintenance of equipment included in the commissioning process. A document that shows sequence of operations of systems. A document that shows the design intent for use during renovation or retro-commissioning
What does a tachometer measure?
The Speed of up to thousands of rpm for an object or substance.
What are the two types of tachometers?
Contact type and Non contact type.
Where does the contact tachometer physically attach to read RPM?
Attached to the motor shaft
How does the non-contact tachometer work?
It uses a brightness sensor that detects rotation.
How does a Strobtac work?
Measures the speed of a fast moving devices or to produce the optical effect of stopping or slowing high speed motion for observation.
Where is the adjustable pulley normally located on the belt driven blower?
On the motor
What is the formula for finding the RPM of the motor for a belt driven blower?
______________________________________
A motor turning 1728 rpm with a 11” pulley, turning a 13” fan pulley. What is the rpm of
the driven?
______________________
A motor turning 1728 rpm with a 11” pulley, turning a 10” fan pulley. What is the rpm of
the driven?
__________________________________________________________________________
____________________
What is the pulley size of the driven when the fan is 1500rpm and 1728rpm for the motor
with a pulley size of 5”?
__________________________________________________________________________
__________________________________________________________________________
What would you have to do to increase the speed of the fan on a belt driven motor?
__________________________________________
What is the belt length formula?
OC=(Dm+Df)1.57+2L
Calculate the belt length if the driver pulley is 3” and driven pulley is 10” with a center line
distance of 13”.
_______________________________________
List the different switches on the line voltage side of the diagram.
________________________________________________________________________________
__________________________
List the power consuming devices that are on the line voltage side.
________________________________________________________________________________
_____________________
What is the voltage of the contact relay? ___
What has to happen for the ignition module to be energized?
How is the pressure switch physically connected to the vent motor?
________________________________
The wires that are coming out of the ignition module to the gas valve must have a common wire,
which is it? ____
Why is it so important to have a ground on the ignition module?
________________________________________________________________________________
What does IDM stand for?
Induced draft motor
What does BLWR stand for?
Blower motor relay
What does FRS stand for?
Flame rollout SW
