Troubleshooting Commerical HVAC Equipment Flashcards
What is the final step that needs to be performed to an HVAC system, meeting the design and/or engineer’s intent?
A start-up
What could possibly happen if the equipment is not started up properly?
May void the manufacturer’s warranty
Why is it important to document the date of start-up on the equipment?
That’s the date the warranty begins
When performing a start-up for a RTU, what should be done to allow the crankcase heater in the compressor to operate properly?
Be 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
What literature should be provided to the building maintenance personnel?
Systems manual, A document that shows sequence of operations, a document that shows the design intent
What does a tachometer measure?
Revolutions per minute (rpm)
What are the two types of tachometers?
Contact type and non-contact type
Where does the contact tachometer physically attach to read RPM?
The motor shaft
How does the non-contact tachometer work?
Uses a brightness sensor that detects rotation
How does a Strobtac work?
They are a source of flashing light that can be synchronized with any fast, repetitive motion.
What is the formula for finding the RPM of the motor for a belt driven blower?
D=D x Sf
_______
Sm
What would you have to do to increase the speed of the fan on a belt driven motor?
To increase blower speed, slightly loosen the setscrew that holds the pulley to the driveshaft. Move or turn the pulley clockwise on the shaft one turn, then tighten setscrew. If more speed is desired, turn the pulley clockwise two turns.
What is the belt length formula?
OC = (Dm + Df) 1.57 + 2L
Where is the adjustable pulley normally located on the belt driven blower?
On the fan
