Thermostats Flashcards
True or False
A thermostat can control the temperature of a conditioned space or a process
true
T or F
“Manual changeover” is the terminology applied to the movement of mercury in a sealed contact type thermostat
false
________ __________ is the changing from the heating mode to cooling mode (and vice versa) by thermal means only
automatic changeover
A ________ is an instrument which responds to changes of temperature and which directly or indirectly controls temperature
thermometer
A bimetal is usually made up of _____ different materials
two
A change in _______ temperature will affect a change in the ______
ambient, bimetal
T or F
“Droop” or “thermal offset” does not affect the operating control point of a thermostat
false
Two commonly used metals in the construction of bimetal temperature sensing elements are _____ and ______
brass and invar
Most exposed type contacts being used today have a magnet added. The magnet provides the _____-____ action making it possible for the electrical contacts to open and close quickly and precisely
detent snap
T or F
Anticipation is the addition of heat to thermostat contacts
True
T or F
Heating cycle anticipators are energized during the heating “off” cycle
false
T or F
Range is the difference between the thermostat min and max operating points
true
The difference between cut-out and cut-in is referred to as the _________
differential
BY adding artificial heat to the thermostat bimetal an increased rate of response by the thermostat is available through a reduced differential is referred to as _________
a) minimum interlock
b) differntial
c) anticipation
d) droop
c) anticipation
The setting of the anticipator in the heating cycle must match the ______ rating
current
T or F
All thermostats should be level
True
T or F
The best thermostat location in a residential installation is eight feet above the floor
False
Always use _______ wiring when installing a thermostat
coloured
The most important step in installing a thermostat is ______
location
The final thermostat should be free of _______ that might make the contacts _____
vibration, close
Thermostat installation should be about ___ feet above the floor
5 feet
T or F
Low voltage (24v) wiring should be thermostat cable or equivalent with single leads of 18awg coloured coded wire as the minimum size for runs under 50 Ft
True
In a heating system, a thermostat bimetal exposed to a false source of _____ may cause an extended “on” cycle
cold
A _____ ______ is a good tool to use to clean exposed contacts
match cover
A differential that is too ______ may cause a system to short cycle
small
When troubleshooting a thermostat for a condition where the system short cycles look for:
a) false source of heat or cold
b) check differential
c) system oversized
d) all of the above
d) all of the above
If the system stays the “ON” cycle too long, check
a) system undersized
b) false source of heat or cold
c) incorrect anticipator setting
d) all of the above
d) all of the above
