Troubleshooting Commercial HVAC Equipment 4th year ILM 110405b

Question 1

What is the final step that needs to be performed to an HVAC system, meeting the design
and/or engineer’s intent?*
________________________________________________________________________

Answer 1

Start-up

Question 2

What could possibly happen if the equipment is not started up properly?
__________

Answer 2

Failure to properly start-up equipment may void the manufacturer’s warranty

Question 3

Why is it important to document the date of start-up on the equipment?
____________________

Answer 3

Because that’s the date that the warranty will begin.

Question 4

When performing a start-up for a RTU, what should be done to allow the crankcase heater
in the compressor to operate properly?
_________________________________

Answer 4

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

Question 5

According to the regulations, who is able to change orifices in an appliance when
required?
_____________________

Answer 5

A qualified technician who holds a gas ticket

Question 6

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?*
_____________________

Question 7

What literature should be provided to the building maintenance personnel?

Answer 7

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

Question 8

What does a tachometer measure?

Answer 8

The Speed of up to thousands of rpm for an object or substance.

Question 9

What are the two types of tachometers?

Answer 9

Contact type and Non contact type.

Question 10

Where does the contact tachometer physically attach to read RPM?

Answer 10

Attached to the motor shaft

Question 11

How does the non-contact tachometer work?

Answer 11

It uses a brightness sensor that detects rotation.

Question 12

How does a Strobtac work?

Answer 12

Measures the speed of a fast moving devices or to produce the optical effect of stopping or slowing high speed motion for observation.

Question 13

Where is the adjustable pulley normally located on the belt driven blower?

Answer 13

On the motor

Question 14

What is the formula for finding the RPM of the motor for a belt driven blower?
______________________________________

Question 15

A motor turning 1728 rpm with a 11” pulley, turning a 13” fan pulley. What is the rpm of
the driven?
______________________

Question 16

A motor turning 1728 rpm with a 11” pulley, turning a 10” fan pulley. What is the rpm of
the driven?
__________________________________________________________________________
____________________

Question 17

What is the pulley size of the driven when the fan is 1500rpm and 1728rpm for the motor
with a pulley size of 5”?
__________________________________________________________________________
__________________________________________________________________________

Question 18

What would you have to do to increase the speed of the fan on a belt driven motor?
__________________________________________

Question 19

What is the belt length formula?

Answer 19

OC=(Dm+Df)1.57+2L

Question 20

Calculate the belt length if the driver pulley is 3” and driven pulley is 10” with a center line
distance of 13”.
_______________________________________

Question 21

List the different switches on the line voltage side of the diagram.
________________________________________________________________________________
__________________________

Question 22

List the power consuming devices that are on the line voltage side.
________________________________________________________________________________
_____________________

Question 23

What is the voltage of the contact relay? ___

Question 24

What has to happen for the ignition module to be energized?

Question 25

How is the pressure switch physically connected to the vent motor?
________________________________

Question 26

The wires that are coming out of the ignition module to the gas valve must have a common wire,
which is it? ____

Question 27

Why is it so important to have a ground on the ignition module?
________________________________________________________________________________

Question 28

What does IDM stand for?

Answer 28

Induced draft motor

Question 29

What does BLWR stand for?

Answer 29

Blower motor relay

Question 30

What does FRS stand for?

Answer 30

Flame rollout SW