Hunter Thermostat Training
Part 1
How It Works
How the Thermostat works
You've probably seen or used a thermostat a thousand times. This device controls the
heating and air-conditioning systems in your house. You’ve probably never seen how one
works though. Within most mechanical thermostats there is a bimetallic strip. A bimetallic
strip is a piece of metal made by laminating two different types of metal together. The
metals that make up the strip expand and contract when they are heated or cooled.
Each type of metal has its own particular rate of
expansion, and the two metals that make up the strip
are chosen so that the rates of expansion and
contraction are different. When this coiled strip is
heated, the metal on the inside of the coil expands
more and the strip tends to unwind. The center of the
coil is connected to the temperature-adjustment lever,
and the mercury switch is mounted to the end of the
coil so that when the coil winds or unwinds, it tips the
mercury switch one way or the other causing the airconditioner or heater to turn on or off.
How the Thermostat works
Also inside a mechanical thermostat is a heat anticipator. This shuts off the heater before the air
inside the thermostat actually reaches the set temperature. Often, some parts of the house will reach
the set temperature before the part of the house containing the thermostat does. The anticipator
shuts the heater off a little early to give the heat time to reach the thermostat. This loop of wire is
actually a resistor. When the heater is running, the current that controls the heater travels from the
mercury switch, through the red wire to the resistive loop. It travels around the loop until it gets to the
wiper, and from there it travels through the hub of the anticipator ring and down to the circuit board
on the bottom layer of the thermostat. The farther the wiper is positioned (moving clockwise) from the
red wire, the more of the resistive wire the current has to pass through. Like any resistor, this one
generates heat when current passes through it. The farther around the loop the wiper is placed, the
more heat is generated by the resistor. This heat warms the thermometer coil, causing it to unwind
and tip the mercury switch to the right so that the heater shuts off.
Digital thermostats use a simple device called a thermistor to measure temperature. A thermistor is
a resistor whose electrical resistance changes with temperature. The microcontroller in a digital
thermostat can measure the resistance and convert that number to a temperature reading.
Hunter Thermostat Training
Part 2
Understanding
Air-Conditioners
Air-Conditioner Operation
An air conditioner is basically a refrigerator without the insulated box. It uses the
evaporation of a refrigerant, like Freon, to provide cooling. The mechanics of the Freon
evaporation cycle are the same in a refrigerator as in an air conditioner.
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The compressor compresses cool Freon gas,
causing it to become hot, high-pressure Freon gas
(red in the diagram to the right).
This hot gas runs through a set of coils so it can
dissipate its heat, and it condenses into a liquid.
The Freon liquid runs through an expansion valve,
and in the process it evaporates to become cold,
low-pressure Freon gas (light blue in the diagram
to the right).
This cold gas runs through a set of coils that allow
the gas to absorb heat and cool down the air
inside the building.
Mixed in with the Freon is a small amount of a
lightweight This oil lubricates the compressor.
Courtesy of WWW.HOWSTUFFWORKS.COM
Split Air-Conditioner Systems
The cold side, consisting of the expansion valve and the cold coil, is generally placed into a
furnace or some other air handler. The air handler blows air through the coil and routes the
air throughout the building using a series of ducts. The hot side, known as the condensing
unit, lives outside the building. In most home installations, the unit looks something like
this:
The unit consists of a long, spiral coil shaped
like a cylinder. Inside the coil is a fan, to blow
air through the coil, along with a weatherresistant compressor and some control logic.
This approach has evolved over the years
because it is low-cost, and also because it
normally results in reduced noise inside the
house (at the expense of increased noise
outside the house). Besides the fact that the
hot and cold sides are split apart and the
capacity is higher (making the coils and
compressor larger), there is no difference
between a split-system and a window air
conditioner.
Courtesy of WWW.HOWSTUFFWORKS.COM
Heat Pump Systems
Imagine that you took an air conditioner and flipped it around so that the hot coils were on the inside and
the cold coils were on the outside. Then you would have a heater. It turns out that this heater works
extremely well. Rather than burning a fuel, what it is doing is "moving heat."
A heat pump is an air conditioner that contains a valve that lets it switch between "air conditioner" and
"heater." When the valve is switched one way, the heat pump acts like an air conditioner, and when it is
switched the other way it reverses the flow of Freon and acts as heater.
Heat pumps can be extremely efficient in their use of energy.
But one problem with most heat pumps is that the coils in the
outside air collect ice. The heat pump has to melt this ice
periodically, so it switches itself back to air conditioner mode
to heat up the coils. To avoid pumping cold air into the house
in air conditioner mode, the heat pump also lights up burners
or electric strip heaters to heat the cold air that the air
conditioner is pumping out. Once the ice is melted, the heat
pump switches back to heating mode and turns off the
burners. Since this type of heating becomes far less effective
as the temperature outside falls, these types of systems are
generally only found in areas where heating is not a major
concern, such as Florida, southern California, and Arizona or
they incorporate a backup or auxiliary gas or electric heating
system.
Hunter Thermostat Training
Part 4
Identifying The
System
Types of Systems
2 Wire Systems
Typical 2 wire systems have just that, 2 wires. They can be of any color combination
and should be small wires about 18 gauge. It is very important when assisting with
the installation of a 2 wire system that you confirm the gauge or size of the wire. Line
Systems will do damage to any 24v Thermostat and potentially the system.
2 Wire System examples are
Heat only, electric or gas
Base Board or “Under Floor” Systems
Radial Heat
Switch Controlled Furnace System
Types of Systems
3 Wire Systems
3 Wire systems are conventionally 24v systems with no common. The third wire can act
as a Conventional Heat System or damper valve on a base board system
3 Wire System examples are
Conventional Heat Systems
Base Board “Under Floor” Systems
Types of Systems
4-5 Wire Systems
4 or 5 wire systems can either be Conventional Heat and Air-Conditioning Systems or
Heat Pump. The difference between them can be identified by the “O or B” as a
reversing wire and may or may not include a common wire. When identifying these
terminals you should always go by the terminal lettering and “NOT” the wire colors.
4-5 Wire System examples are
Conventional Heat Systems
Single Stage Heat Pumps
Multi-stage systems
Types of Systems
6+ Wire Systems
With 6 or more wires these systems will either be Multi-stage Heat Pumps or
Conventional Systems with more than one stage of heat and or cool. Again, to identify
the difference between the systems you should check first for a reversing wire then for
multiple heat or cool wiring.
6+ Wire System examples are
Multi-stage systems
Multi-stage Heat Pumps
Hunter Thermostat Training
Part 6
Mechanical
Thermostats
Mechanical Thermostats
This is the typical thermostat that you will see in most homes,
and probably grew up with in your own. Simply rotate the dial
to choose your temperature and the unit will do the rest. Later
units not only had a “cool” and “heat” selector but also an auto
that would change between heat and cool if a certain
temperature drop or raise in temperature occurred.
These types of thermostats usually had to be leveled perfectly
to allow the mercury bulb in the thermostat to rock back and
forth with the heating or cooling of the bimetallic coil to activate
heat or cooling.
Mechanical Thermostats
Hunter mechanical thermostats no longer use the mercury bulb to adjust heating or cooling. Now, a
simple magnetic pin is used to make contact and bridge connections. The magnet activates the
switches in the thermostat to turn on heat or cool. The advantage to this is there is no longer an
issue of disposing of the dangerous mercury vial and it helps give more precision in
temperature.
Hunter Thermostat Training
Part 6
Digital
Thermostats
Digital Thermostats
Digital thermostats do not read temperature the same as their mechanical counterparts. Digitals
use a thermistor to register temperature. A thermistor is a type of resistor used to measure
temperature changes, relying on the change in its resistance with changing temperature. This
does lead to more accurate temperature calculations vs. it’s mercury counterpart on many
mechanical thermostats but depending on the placement of the thermistor, it can cause some
new problems.
Many digital thermostats have an additional feature on them incase the thermistor is reading
inaccurately called calibration. Calibration allows you to change the base reading by + or –
degrees to more accurately reflect the room temperature. Currently no Hunter thermostat offers
calibration.
Digital Thermostats
Another feature of many digital thermostats is the ability to program them to
change temperatures ad different times during the day to accommodate
the consumers life style. Each manufacturer can handle this differently as
far as setting up the programs and how they operate.
Keep in mind, not all digital thermostats are programmable.
Hunter Thermostat Training
Part 3
Wiring a
Thermostat
Thermostat Wiring
There are 4 basic terminals on most thermostats
R - This wire is normally the "Hot" terminal for the system. It is also commonly listed as RC, RH, V, VR,
or 4. It may exist as a single item or there may be more than one (i.e. RH and RC).
G - This wire is for control of the interior fan or air handler. It is also commonly listed as F.
Y - This wire is for control of the compressor. It is also commonly listed as Y1, Y2, and M. There may
also be multiple stages or compressor speeds denoted as Y Y1 or Y1 Y2.
W - This terminal controls the auxilary heating system if one exists. It is also commonly listed as W1,
W2. Like the compressor it may have multiple stages with W, W1, and W2 appearing in
combination with one another.
Thermostat Wiring
Additional Terminals
O - This terminal controls the reversing valve in a heat pump system. It is also commonly
listed as B. In general when the wire is connected to a terminal marked O, the reversing
valve is switched on in the cooling mode. In general when the wire is connected to a
terminal marked B, the reversing valve is in operation in the heating mode.
E - This terminal controls the emergency heat relay in heat pump systems. This relay is
used to lock the compressor in the off mode when the thermostat calls for heat in the
emergency mode. In some systems it also locks the system into a manual mode where
the thermostat must be switched on and off to turn the heat on and off. IF this is the
case and it is undesired, this can be avoided by disconnecting the wire from the E
terminal and taping it off.
C - This terminal is the common wire for the system. It is also commonly listed as X, X1, X2,
and B.
Hunter Thermostat Training
Part 5
Selecting a
Thermostat
Selecting a Thermostat
Hunter has many different types of
Thermostats and many can be used for
more than 1 type of system. This next
chapter will help you identify the type of
thermostat a Consumer would need based
upon the wiring in their old Thermostat they
are removing.
Line Voltage Systems
Line voltage systems use
110 volt house power to
operate the thermostat
and the systems. Hunter
products only support 2
wire Line Voltage
Systems. Line voltage
wires will be thicker
40351
Conventional Heat and Air
Consumers have various
options as to which
Thermostats will work with
a “traditional” system. The
choice will depend upon,
mechanical or digital, and
programming options.
In addition to this, the
model 42996 is the only
remote based thermostat
we make at this time.
40035
40050
40070
40170
42999
42995
42996
44100
44110
44150
44200
44250
44260
44300
44350
44360
44550
44660
44665
Single Stage Heat Pumps
Options are
decreased a bit with
Single Stage Heat
Pumps but still offer a
wide enough
selection to
accommodate most
individuals.
Remember, the
44760 requires a
common wire, even
for a Single Stage
Heat Pump.
40070
40170
44260
44360
44550
44660
44665
44760
Multi-Stage Systems,
Heat Pumps
None of Hunters Retail
thermostats at this time offer
connections for Multi-stage
Systems.
Please refer to our CTC line of
products available commercially
for
multi-stage traditional systems.
The 44760 is made specifically
for Heat Pumps.
44760
Hunter Thermostat Training
Part 7
CTC, our
Commercial
Products
Climate Technology Product Line
Our CTC, or Climate Technology Company, line reflects
their retail counterparts. Some do add additional
functionality and their warranty is 5 years compared to the
1 year our retail versions carry.
Climate Technology Product Line
Models 43054, 43058, and 43558 all have additional or new features.
The 43054 is the same as the 42999 in our retail version with the exception of it’s ability to control a
Single Stage Heat Pump and it’s use of “Indiglo” technology.
The 43058 is a model 44760 with the exception of programming and Multi-stage Systems. The
43058 is a nonprogrammable model of the 44760 and will also control 2 stage heat / 2 stage cool
systems.
The 43558 is the same as the 44760 with the addition of 2 stage heat / 2 stage cool systems.
Climate Technology Product Line
All other CTC thermostats will program and react as it’s Retail thermostat.
Examples of this are.
44260
44360
43154
43255 – 5-1-1
43355
44550
43503
Climate Technology Product Line
The newest additions to the CTC line of thermostats is the 43057 and 43855.
The 43057 controls heat pumps only and runs on 30v ac or less with no programming options and
requires a common wire.
The 43855 is a 7 day programmable touch screen thermostat that can be used on all systems
including multi-stage systems or heat pumps. Common wire use is optional on this thermostat.
Hunter Thermostat Training
Part 8
Programming a
Hunter
Thermostat
Programming a Hunter Thermostat
Programming a Hunter thermostat doesn’t have to be daunting, the key is understanding your
options in programming. We have 3 main programming styles within the Hunter digital thermostat
family we will go over.
Programming a Hunter Thermostat
The first to go over is the 42995 and 42996 - remote.
Even though this thermostat is not programmable there are some things you
should understand about how the remote feature operates. When using the
remote sensor to adjust the temperature, you can only raise or lower the
temp 2 degrees plus or minus the current room temperature. So if the room
temp is 70 degrees, you can only adjust the thermostat to 68 / 72.
Once the room temperature changes it can
be readjusted under the same conditions.
It is also important to note that there are
jumpers, just like our remote fans, on the
transmitter and thermostat that may need
to be adjusted for frequency. Other than
this, it reacts just like a 42999 or 42995.
Programming a Hunter Thermostat
The first type to go over is used for example on the 44260.
This style of programming requires
you to repeatedly use the “program”
button to maneuver through the
programs. Program once to set the
hour, again to set the minutes, yet
again to set the temperature, and last
to move to the next program. This
same process is used to set the
current time and day of the thermostat
via the time/day button.
Programming a Hunter Thermostat
The next type to go over is used for example on the 44360.
This style of programming requires
you to repeatedly use the “program”
button to maneuver through the
programs also. Program once to set
the hour, again to set the minutes, yet
again to set the temperature, and last
to move to the next program. The
program day button is used to move
between the program sets 5/2 or 7
day.
Programming a Hunter Thermostat
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The 44660, 44665 Thermostats and sensor
The 44660 and 44665 have the same programming as a
44360. The difference between the 2 is the 44665
comes with and can use up to 3 44758’s to register
temperature. The 44758 is remote sensor that reports
temperature to the thermostat. If for example you placed
one of these in your bedroom, and the thermostat is
mounting in your living rooom, you could have the
44758 report the bedroom temperature to the thermostat
and run the programs according to that temperature.
Like wise one can be installed outside, as the
thermostat can also display temperatures from the
remote sensors individually.
Programming a Hunter Thermostat
Last to go over is used for example on the 44550.
The programming type for these
thermostats is different than the
previous. Program moves you through
the program sets but you use the hour
and minute buttons to set the
activation times and the up and down
arrows to set the temperature. Again,
program day changes the program
sets between 5/2, 7 day, and
“everyday” settings.
The 44760
The 44760 can be the most difficult thermostat we have to walk a customer
through, but it doesn’t have to be. Remember these tips and you will come out
a winner every time.
The system button changes between
heat, cool, and auto features
Fan turns the fan on and off
It programs like a 44360 would
Option sets all other aspects
Hunter Thermostat Training
Part 9
Troubleshooting
and
Performing a wire
test
Wire testing and troubleshooting
When troubleshooting a thermostat it is important to remember a few facts.
Always ask how long the thermostat has been installed and running properly. The
customer may reveal it has never worked in it’s current mode before. This could
indicate a wiring or system problem.
Many consumers will replace their previous thermostat thinking it has a problem or
is defective and this is not always the case. Always ask the consumer their
reasons for replacing their old thermostat, it may point to a system problem if
both are having similar problems.
Wire testing becomes necessary when a part of the system is not running or the
customer gets no operation at all. Wire testing allows you to determine if the
system or thermostat is at fault.
Some customers will have concerns about handling electricity. The lines they are
handling are under 30V. It might scare them if shocked, but definitely should not
cause harm.
Wire testing and troubleshooting
Wire testing a conventional thermostat is actually very simple. You have 2 ways
you can have the consumer achieve this. The first method would be to have the
customer find a conductive source. This can be a paperclip, 2 nails, even small
scissors. Anything that will make contact between the screws holding down the
wires.
Remembering your wire terminal descriptions, you will have the customer bridge
power / heat, power / cool or, power / fan. Depending on where the problem
lies.
Also, you can remove the wires from their terminals and have the customer touch
them together to achieve the same result.
Either of these methods work, it is all about what you and the consumer feel
comfortable with.
Wire testing and troubleshooting
Wire testing for a heat pump is similar in the tools and wiring you use but the additional to this is
obvious, your reversing valve wire. Single stage and multi stage are going to wire test.
You must remember a few things when trying to wire test with a heat pump. If the consumer has
an “O” reversing wire to reverse for cool, it is impossible to get cooling to activate without
using it in the wire test. Not using the reversing valve during a wire test with this terminal
will always give you heat, no matter what other contactor you use with the power wire, “W”
or “Y”.
If the consumer has a “B” reversing valve, this reverses heat, and works the exact opposite of
the above example.
To perform a wire test of this nature, you would connect the power wire, fan wire, and possibly
the reversing wire with the other contactor wires such as w or y to achieve a proper test.
Once the wire test has been performed it should be pretty easy to determine where the
problem lies.
*** “O” terminals reverse cooling, “B” terminals reverse heat. It is impossible to to achieve one without the other.***
****
WARNING
****
If the customer cannot identify any or all of the
wires according to terminal, we cannot assist with
connections. The customer must be able to tell us
the terminal letters used for each wire, not color. If
the consumer does not know this or only can
identify by the color of the wire, they will have to
gather that information and call us back or contact
their local HVAC technician to assist them.
**Improper wiring can cause damage to
the thermostat as well
As the A/C or Heat Pump Unit. Always
Know what your wiring!**
Helpful Hints

12/24 and C/F set different for each model, consult with your cheat sheet for programmable
thermostats.
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The anticipator on manual models affects the length of the cycle for heat only. Check this
before you replace a thermostat for not shutting down.
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Thermostats with auto season changeover, be sure the heat and cool cycles are set a
minimum of 3 degrees apart.
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If the consumers says the unit won’t shut off on programmable models, make sure the fan
switch is in auto and the system selector switch is correct.
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Low battery won’t clear on the screen? Try resetting the Thermostat.
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Always check 2 wire systems for line voltage wires.
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“O” terminals on a heat pump reverse to give cooling, “B” terminals reverse to give heat. It is
impossible to get one without the other.