What are three types of switching mechanisms used in low voltage thermostats

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All of the following are true statements about receiver driers EXCEPT
A vac door actuator is being tested. When vac is applied with a pump the door does not move and the reading on the gauge is 0. Tech A says it is because the door is binding or obstructed. Tech B says the actuator is defective. Who's right ?
What is the minimum system pressure necessary to leak test with an electronic leak detector ?
To properly evacuate an AC system the vac pump should be run for:
All of the following are causes for fan clutch replacement except
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Convection
Which of the following is a TRUE statement about R134a ?
. Oil lines can be constructed of _____, ______,______ pipe connected with malleable fittings.
Atom
Conduction
During AC system operation a knocking sound can be heard coming from the compressor. Tech A says there can be internal compressor damage. Tech B says that the compressor mounting brackets and bushings should be checked. Who is right?
Ohm's law
When Diagnosing an ATC system most of the system temp sensors can be tested for:
Compound
Electrolyte
Oil burner nozzles are designed and rated at 100 psig nozzle pressure.
An oil burner equipped with the CAD cell relay will ignite, run for about ninety seconds, and cut off. What is the first thing the service technician should do?
Tank piping should be inspected regularly for imperfections and leaks.
Latent heat of fusion
If a technician inspects the interior of a combustion chamber and finds large quantities of unburned oil, he would correctly conclude that ____.
ASHRAE
why should a safty control not be adjusted if it has a seal to prevent tampering
HVAC
What changes its resistance depending on the amount of light it senses
Which system provides makeup to the Laundry Water System?
shock or surge arrestor
Conductivity
A capacitor is a device that stores a quantity of ____________ .
The __________ is an oil piping component that allows a one-pipe system to function as a two-pipe system.
Name two actions that can be obtained with a pressure change
Improper combustion can lead to ____.
Describe the purpose of the Plant Heating System, Central Chilled Water System and the Freeze Protection/Heat Trace System.
TRAC
what component steps down the voltage to a low voltage value
Motors used in refrigeration systems may need as much as _________more current to start than to run at design speeds.
how can an electric thermometer be used in a well to obtain an accurate response?
What happens to the capacitance of a capacitor if the plate area is doubled, all other factors being equal?
RA