Difference between revisions of "Indoor Thermostat"

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(Hot Wire Testing)
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== Hot Wire Testing ==
 
== Hot Wire Testing ==
  
 
Shorting or Hot Jumping is risky and can in face damage your system.  Certain brand and models work differently from what is commonly known.  Use this as a general reference but do not proceed unless you have research your system brand and model.
 
Shorting or Hot Jumping is risky and can in face damage your system.  Certain brand and models work differently from what is commonly known.  Use this as a general reference but do not proceed unless you have research your system brand and model.
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=== 5 Wire Red, Blue, White, Green, Yellow ===
 
=== 5 Wire Red, Blue, White, Green, Yellow ===
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* Red + Green - turns on the blower fan
 
* Red + Green - turns on the blower fan
 
* Red + White - turns on heat
 
* Red + White - turns on heat
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== Common HVAC Thermostat Wiring ==
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=== (R) Red - Voltage ===
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Transformer provided DC voltage
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=== (G) Green - Blower Fan ===
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Many thermostats (G) and (Y) terminals are connected together at all times when the fan switch is in the "Auto" mode.
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=== (Y) Yellow - Compressor ===
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The Air Conditioner.  When voltage supplied it activates cooling.  On a Heat Pump system it can also activate heat via the heat pump.
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=== (W) White - Heat ===
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Activate heat. Heat including gas heat, electric heat, or auxiliary heat on a heat pump.
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=== (B) Blue - Common (exceptions exist) ===
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What is called 'common' and is typically not used on modern thermostats. 
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Needed on some electronic thermostats or if the system uses indicator lamps.
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On some Rheem & Ruud systems it is not 'common'.  May be Blue or Orange.
  
 
 
 
 

Revision as of 21:42, 29 June 2011

A building thermostat is a device to control the heating and air-conditioning systems in a home, office, or other indoor environment.

The majority of modern heating/cooling/heat pump thermostats operate on 24 volts A/C.

4 Wire 24V HVAC Thermostat Wire Diagram

W : White Wire : Heat

Y : Yellow or Black Wire : Cool

G : Green : Fan

R : Red : 24v

Jump W + R will turn on heater on a gas operated HVAC system. On the gas system the fan is triggered automatically at the heater when a certain temperature is reached.

Jump G + R to force the fan to turn on

Honeywell's round mechanical mercury thermostat "The Round" has 6 connectors. Only 4 are necessary for a typical HVAC system.

B : black

G : green : Fan

Y : yellow : Cool

W : white : Heat

R : red : 24v

O : orange

A modern electronic thermostat may have as many as 8 connectors. To connect this to a 4 wire 24v system use the following:

W : white : heat

Y : yellow or black wire : cool

G : green : fan

B :

O :

RC : red wire : 24v - bridge to RH

RH : red wire : 24v - bridge to RC

C :

 

Hot Wire Testing

Shorting or Hot Jumping is risky and can in face damage your system. Certain brand and models work differently from what is commonly known. Use this as a general reference but do not proceed unless you have research your system brand and model.

 

5 Wire Red, Blue, White, Green, Yellow

  • Red + Yellow - turns on the Air Conditioner
  • Red + Green - turns on the blower fan
  • Red + White - turns on heat

 

Common HVAC Thermostat Wiring

(R) Red - Voltage

Transformer provided DC voltage

(G) Green - Blower Fan

Many thermostats (G) and (Y) terminals are connected together at all times when the fan switch is in the "Auto" mode.

(Y) Yellow - Compressor

The Air Conditioner. When voltage supplied it activates cooling. On a Heat Pump system it can also activate heat via the heat pump.

(W) White - Heat

Activate heat. Heat including gas heat, electric heat, or auxiliary heat on a heat pump.

(B) Blue - Common (exceptions exist)

What is called 'common' and is typically not used on modern thermostats.

Needed on some electronic thermostats or if the system uses indicator lamps.

On some Rheem & Ruud systems it is not 'common'. May be Blue or Orange.