U.S. Department of Energy U.S. Department of Energy Energy Efficiency and Renewable Energy

Thermostat Controls

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Air flow is produced when central HVAC fan is energized (set thermostat to “fan”)

Scope


Whole House Ventilation

 

Thermostat controls are defined as follows:

Air flow is produced when central HVAC fan is energized (set thermostat to “fan”):

  1. Turn the fan on at the thermostat.
  2. Reset the thermostat to the original settings before continuing.

 

Cool air flow is produced when the cooling cycle is energized (set thermostat to “cool”):

  1. Turn the system on to cool and change the set point temperature to 3 degrees below the ambient temperature.
  2. Reset the thermostat to the original settings before continuing.
  3. If the system does not have air conditioning, this item does not need to be verified.

 

Heated air flow is produced when the heating cycle is energized (set thermostat to heat):

  1. Turn the system on to heat and change the set point temperature to 3 degrees above the ambient temperature.
  2. Reset the thermostat to the original settings before continuing.


Notes:
     
In cases where the condenser unit is installed after the time of inspection by the rater, the rater is exempt from verifying the cool air flow when the condenser is for an AC unit and also heat air flow when the condenser is for a heat pump unit.


To prevent potential equipment damage, the rater shall not conduct the cool air flow test if the outdoor temperature is < 55°F or, if known, below the manufacturer-recommended minimum operating temperature for the cooling cycle. When this occurs, the rater shall mark ‘N/A’ on the ENERGY STAR checklist for this item.

Description


In homes with central HVAC equipment, a programmable thermostat should be installed. This thermostat should be tested by the HERS rater to ensure that the fan, cooling, and heating settings operate.

 

If the system does not have cooling, this item does not need to be verified.

 

In cases where the condenser unit is installed after the inspection by the rater, the rater is exempt from verifying the cool air flow. If the condenser is part of a heat pump, the rater is also exempt from testing hot air flow.

 

To prevent potential equipment damage, the rater shall not conduct the cool air flow test if the outdoor temperature is less than 55°F or below the manufacturer-recommended minimum operating temperature for the cooling cycle, if that is known. When this occurs, the rater shall mark ‘N/A’ on the ENERGY STAR checklist for this item.

 

How to Test Air Flow

  1. Manually turn the fan to "on" at the thermostat
  2. Check for air flow at supply registers
  3. Reset the thermostat to the original settings before continuing.

 

How to Test Cooling Setting

  1. Manually set the system to “cool” at the thermostat and set the fan to "auto." If the system does not have air conditioning, this item does not need to be verified
  2. Change the set point temperature to 3°F below the ambient temperature
  3. Check for cool air flow at the supply registers
  4. Reset the thermostat to the original settings before continuing.

 

How to Test Heating Setting

  1. Manually set the system to "heat" at the thermostat and set the fan to “auto”
  2. Change the set point temperature to 3°F above the ambient temperature
  3. Check for warm air flow at the supply registers
  4. Reset the thermostat to the original settings.

 

 

The HERS rater should test the thermostat fan, cool, and heat settings to make sure the system blows ventilation, cooled, and warmed air.

Figure 1 - The HERS rater should test the thermostat fan, cool, and heat settings to make sure the system blows ventilation, cooled, and warmed air.  Reference



Ensuring Success


In homes with central HVAC equipment, a programmable thermostat should be installed. This thermostat should be tested by the HERS rater to ensure that the fan, cooling, and heating settings operate.

 


Climate


No climate specific information applies.



Right and Wrong Images

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Presentations

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Videos

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CAD Images

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Compliance


ENERGY STAR Version 3, (Rev. 6)

HVAC System Quality Checklist, Controls. Air flow is produced when central HVAC fan is energized (set thermostat to “fan”). Cool air flow is produced when the cooling cycle is energized (set thermostat to “cool”). In cases where the condenser unit is installed after the time of inspection by the Rater, the Rater is exempt from verifying cool air flow when the condenser is for an AC unit and also from heated air flow when the condenser is for a heat pump unit. To prevent potential equipment damage, the Rater shall not conduct this test if the outdoor temperature is ≤ 55°F or, if know, below the manufacturer-recommended minimum operating temperature for the cooling cycle. When this occurs, the Rater shall mark ‘N/A’ on the Checklist for this item. Heated air flow is produced when the heating cycle is energized (set thermostat to “heat”).

 

DOE Challenge Home

Exhibit 1: Mandatory Requirements. Certified under ENERGY STAR Qualified Homes Version 3.

 

2009 IECC

Section 403.1.1 Programmable thermostat. Where the primary heating system is a forced air-furnace, at least one programmable thermostat is installed to control the primary heating system and has set-points initialized at 70 degree F for the heating cycle and 78 degree F for the cooling cycle.*

 

2009 IRC

Section N1103.1.1 Programmable thermostat. Where the primary heating system is a forced air-furnace, at least one programmable thermostat is installed to control the primary heating system and has set-points initialized at 70 degree F for the heating cycle and 78 degree F for the cooling cycle.*

 

2012 IECC

Section R403.1.1 Programmable thermostat. Where the primary heating system is a forced air-furnace, at least one programmable thermostat is installed to control the primary heating system and has set-points initialized at 70 degree F for the heating cycle and 78 degree F for the cooling cycle.*

 

2012 IRC

Section N1103.1.1 Programmable thermostat. Where the primary heating system is a forced air-furnace, at least one programmable thermostat is installed to control the primary heating system and has set-points initialized at 70 degree F for the heating cycle and 78 degree F for the cooling cycle.*

 

 

*Due to copyright restrictions, exact code text is not provided.  For specific code text, refer to the applicable code.

 



Case Studies

None Available


References

  1. 2009 IECC—International Energy Conservation Code

    2009 IECC, International Energy Conservation Code. International Code Council, Washington, D.C.

  2. 2009 IRC—International Residential Code for One and Two Family Dwellings

    2009 IRC, International Residential Code for One and Two Family Dwellings. 2009. Fifth Printing. International Code Council, Washington, D.C. 

  3. 2012 IECC—International Energy Conservation Code

    2012 IECC, International Energy Conservation Code.  International Code Council, Washington, D.C.

  4. 2012 IRC—International Residential Code for One and Two Family Dwellings

    2012 IRC, International Residential Code for One and Two Family Dwellings. 2012. Second Printing. International Code Council, Washington, D.C.

  5. DOE Challenge Home National Program Requirements

    DOE. 2012. DOE Challenge Home National Program Requirements (Rev. 02). Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy, Washington, D.C.

  6. ENERGY STAR Qualified Homes, Version 3 (Rev. 06) Inspection Checklist for National Program Requirements

    EPA. 2012. ENERGY STAR Qualified Homes, Version 3 (Rev. 06) Inspection Checklist for National Program Requirements. U.S. Environmental Protection Agency, Washington, D.C.

  7. HVAC System Quality Installation Rater Checklist

    EPA. 2011. HVAC System Quality Installation Rater Checklist. U.S. Environmental Protection Agency, Washington, D.C.



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