Hvac final correct stuvia - Study guides, Class notes & Summaries

What is the function and operation of a reversing valve - ANSWER Reverses refrigerant flow and provides both heating and cooling. Diverts the discharge gas. What are common failures of reversing valves and causes - ANSWER Stuck valve Overheating Bad coil Leaking by from discharge gas flowing back into the suction line How is metering of refrigerant accomplished with a heat pump? - ANSWER We need to add check valves bypass lines and bi-directional txv's What components should be ener...

When a water regulating valve is used to control the head pressure of a water-cooled system, the valve's spring is acting against which pressure to modulate the water flow? - ANSWER Head pressure of the system To prove that the combustion blower motor is operating before ignition, a ______ would be used. - ANSWER Sail switch The difference between system overshoot and system lag is called? - ANSWER Temperature swing The purpose of a heat anticipator is to_____. - ANSWER Reduce the temp...

AC is an electron flow that _________________________ - ANSWER alternates back and fourth The ______ is often used as a graphical representation of alternating current - ANSWER sine wave when a conductor rotates through one complete revolution it has generated _____ flow reversals - ANSWER two the __________of alternating current is the number of complete cycles that occur in a second. - ANSWER frequency Alternating current reaches a peak at ________________ electrical degrees - ANSW...

A load is an electrical device that _____________________________ - ANSWER uses electricity to do useful work A disconnect switch is used to __________ - ANSWER open and close the main power source to a piece of equipment which of the following are not components of a contactor or relay? - ANSWER thermal element Loads are electrical devices that consume electricity to do _______________ work - ANSWER useful _____ are devices such as motors solenoids resistance heaters and other curre...

To control ice build-up on a heat pump outdoor coil in the heating cycle, a ____ is attached to a large diaphragm. - ANSWER Microswitch The heater in the thermostat control circuit in the cooling mode is active when the - ANSWER Cooling contact is open If the suction pressure of a system is 60 psi and the oil pump is 85 psig, what is the net oil pressure? - ANSWER 25 psig What is meant by the term "detent" ? - ANSWER opening or closing of a contact The heat anticipator in the therm...

What is an HVAC System? - ANSWER all the items needed to maintain thermal comfort within a space or group of spaces What are the four components of an HVAC system? - ANSWER Fans Pumps Compressor Evaporator What is a PTAC? - ANSWER Packaged Terminal Air Conditioner What is a PTHP? - ANSWER Packaged Terminal Heat Pump List the heat transfer equipment (3) - ANSWER Boiler Chiller Coil What is a zone? - ANSWER A zone is a separately controlled space or group spaces What is VAV ...

A control can be which of the following? - ANSWER All of the above An example of a power consuming device would be a(n) ____ while an example of a non-power consuming device would be a(n) _____. - ANSWER Light bulb, single-pole single-throw switch An electrical power consuming component. - ANSWER is also known as a load The line side of a switch is the. - ANSWER side the power source is connected to If an air conditioning system is calling for cooling and the compressor is running bu...