Why is my Heating not Working?

Last updated

This guide is intended for users with heating and cooling forced-air systems

Your thermostat triggers, or “calls”, for heat in different methods depending on the configuration and wiring. This FAQ is intended for thermostats that were newly installed or have not previously been providing heat.

  • Issues where the thermostat was previously heating normally are addressed in the “Additional Steps” below and may need to be addressed by a local HVAC professional.
Important

If you have a dual-fuel system (a system that provides heat with a heatpump or electric furnace, with a back-up heat source fueled by oil or gas) we strongly recommend contacting an HVAC professional.

  • Incorrectly wiring or configuring the thermostat may cause damage to your system.

BEFORE YOU BEGIN

If your heating is not working, it’s probably due to issues with the following:

  • Air Flow
  • Heating or Furnace System
  • Thermostat Wiring
  • Thermostat Screen
  • Thermostat Functionality

AIR FLOW

What best describes the air coming out of your vents?

  • NO AIR - Continue to the Furnance or Heating System section
  • ROOM TEMPERATURE - Continue to the Thermostat Functionality section.
  • WEAK HEAT (WARM) - Continue to the Fan section.
  • COLD - Continue to the Thermostat Functionality section.
Furnace or Heating System

Go to your home’s circuit breaker and make sure the breaker to the furnace is turned on. Next, go to your furnace or heating system, often located in your basement, attic, or garage.

  1. Make sure your furnace is turned on
  2. There's usually a switch next to your furnace that turns it on or off. It sometimes looks like a light switch.

    Make sure the furnace is closed.

    Be sure the cover is completely closed. Some systems won't power up if the cover isn't fully closed.

    Are there any error lights on the furnace? Most furnaces have lights on them. When there's an error, this light will flash or blink rapidly. There's typically an error code reference guide inside the furnace cover. If you see an error code, contact the manufacturer of your furnace or Support at 1-855-733-5465 to find a pro-installer in your area.
     4. Go to your vents
  • If so, continue to the Thermostat Wiring section.
  • If not, contact a pro-installer in your area.

Thermostat Wiring

  • Remove the thermostat face plate and take a picture of your wiring, and of the label on the back of the thermostat to reference later.
  • Look closely at the terminals labeled R and Rc. If you have only one wire, connected to either R or Rc, move it to the R terminal and make sure the jumper (connector between 2 terminals) is installed between the R and Rc terminals) *jumpers will vary by thermostat model.

Additional Notes:

  • For thermostats with separate O/b and W terminals, make sure there is only one wire in either W or O/b. If you know you have a heat pump, move the W wire to the W2 terminal.
  • For non-heat pump systems (gas/oil furnaces or boilers) W controls the heating. Make sure a wire is connected to W for these systems. For all systems, the compressor is controlled from the Y terminal. Verify a wire is connected to Y (if you have cooling or a heat-pump).
  • For all systems, the fan is controlled by the G terminal. Check that you have a wire connected to the G terminal.
  • The W2, Aux, and E terminals are for multiple/ backup heat stages.
  • The Y2 terminal is for the 2nd compressor stage.
  • The K terminal is for the C-Wire Adapter. For purposes of this FAQ, the K terminal provides both compressor (Y terminal) and fan (G terminal) control.
  • The C terminal and wire provide common power. It is required for all Wi-Fi thermostats.

terminal  2 transformer system

                                                                                                                          (2 transformer system)

 

diagram 1             Diagram 2

Some models use a small wire, similar to a metal staple.

diagram 3

Some use a selector switch that closes/blocks the Rc terminal and links the R and Rc terminals together.

diagram 4

Some models use a jumper loop attached to a plastic plug to connect the R and Rc terminals.

Now look at the terminal labeled O/b. This terminal typically indicates a heat-pump system.

outdoor ac unit

Heat pump systems use the outdoor compressor to provide both cooling and heating. If your outdoor compressor previously ran when your system is heating, you have a heat pump.

diagram 5

Some models, the O/b terminal is shared with another letter (typically W or W1), which allows the user to change the operation of the terminal, based on the system type programmed in the thermostat setup/configuration.

Thermostat Screen

  1. Now, place your thermostat back on the wall plate, and make a call for heat (set the mode to “Heat”, and the set- point at least 2 degrees higher than the displayed temperature. Wait for “Heat On”, the “Fire” icon, or the “sun” icon to appear (if the message/ icon is flashing, allow 3-5 minutes for heating to begin. The message / icon will remain solid when actively heating).

  2. If you feel Cool air instead of heat, you likely have misconfigured your system type or reversing valve. Using your manual, enter the thermostat configuration and change the reversing valve setting and re-attempt to call for heat / return to step 1. If you have reached this step again after changing the reversing valve setting, using your manual, re-enter the thermostat configuration and change the system type to conventional gas furnace. Then, re-attempt to call for heat / return to step 1.

  3. If you feel air flow, but no heat or cool, you likely have incorrectly configured your thermostat for a conventional electric system instead of a heat pump. Using your manual, enter the thermostat configuration and change the system type setting and re-attempt to call for heat/ return to step 1.

  4. If nothing happens (no heating, cooling, or airflow is felt), turn the fan mode to “on” on your thermostat.

  5. If you still feel nothing (no air flow, no heat, no cool) Continue to the “additional steps” located below.

  6. If you now feel heat and air flow, you likely have incorrectly configured your thermostat for a conventional gas/ oil system instead of a conventional electric. Using your manual, enter the thermostat configuration and change the system type setting and re-attempt to call for heat/ return to step 1.

  7. If you feel air flow, but no heat or cool, you likely have incorrectly configured your thermostat for a conventional system instead of a heat pump. Using your manual, enter the thermostat configuration and change the system type setting and re-attempt to call for heat/ return to step 1.


Heating or Furnace System

breaker switch off

  • Make sure the HVAC system breakers are on, and that the power switch is mounted to the HVAC is on.
  • Make sure the doors/panels to the HVAC system are closed properly (Many systems have a safety switch on one or both doors that prevents operation when the unit is open)

  • Check the fuse on the Furnace Control Board (located inside the furnace)
  • Verify the thermostat wires match the designations at the Furnace control board and take a picture (follow the wires out of the furnace to the wall-look for splices)

  • Check the HVAC system for error codes (a small sight-glass / LED is typically visible, look for sequences of flashes that may indicate a problem. A description of the codes is typically mounted to the inside of the fur- nace doors)
  • Using a multi-meter, measure AC voltage between R (or Rc) and each other wire at the thermostat. For wires connected to the HVAC system. The thermostat operates between 20-30VAC. Readings below 20VAC may indicate a short, and readings above 30VAC may indicate a bad transformer. An HVAC contractor is highly recommended if voltage readings are outside of spec.
  • For further questions, contact Resideo Support, or a local HVAC professional for assistance with your system.

Thermostat Functionality

Go to your thermostat and switch from Heating to Cooling and then feel the temperature of the air blowing from the vent.

  • If COLD, this means your thermostat is cooling correctly, but the heating isn’t working properly. Contact Support at 1-855-733-5465 to find a pro-installer in your area.
  • If WARM/HOT, this means your reversing valve may not be configured or wired properly. Continue to the Thermostat Wiring section.

Next, turn on fan mode on your thermostat and feel for air from the vent. Is your heat working at full force?

  • If yes, there’s nothing wrong with your system, but it’s not correctly configured. Contact Support at 1-855- 733-5465 to find a pro-installer in your area.

If not, continue to the next step and remove your existing thermostat from the wall plate.

  • On most thermostats, you can take off the thermostat by grasping and gently pulling. Some thermostats may have screws, buttons, or clasps.
  • Note: Don’t remove any wires from your thermostat at this time.
Do you have a wire connected to the G-Terminal?

  • If yes, you have a G-Wire, but your fan isn’t working properly, your system may need servicing. Contact Sup- port at 1-855-733-5465 to find a pro-installer in your area.
  • If not, you require a G-Wire to run your fan. Contact Support at 1-855-733-5465 to find a pro-installer in your area.

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