Documented in Utility Commissioned Work Papers

Save Money & Energy with CWS HVAC CHIP

CWS HVAC CHIP is SFT (Smart Fan Technology). CWS HVAC CHIP adjusts the HVAC blower to stay on for an extended period of time after the cooling and heating unit cycles off. Most systems are designed for the fan to be set to run 30, 60 or 90 seconds after cycling down automatically. CWS HVAC CHIP reads recent system activity and tells the fan to remain on for a precise amount of time for each cycle to optimize that activity. CWS HVAC CHIP tells the fan exactly how long to run, as long as five minutes, to most efficiently use the conditioning capacity of the elements of the HVAC system. CWS HVAC CHIP increases efficiency and reduces the number of times the HVAC system cycles on and off during a given time period. CWS HVAC CHIP is a smart chip designed specifically to reduce energy consumption and utility costs. Independent studies show seasonal savings of 12-15 % on HVAC energy expenses.

Features and Benefits

  • California utilities, including S.C.E., P.G.&E. and SDG&E have found savings of 12-15% in independent studies of SFTs.
  • Leading installers for Ca. utility rebate programs use CWS HVAC CHIP as the preferred Smart Fan Technology based on price and performance
  • A proven energy saver in both heating and cooling modes
  • Extends the ventilation fan runtime for a programmed period after compressor or heater shuts off
  • Reduces the number of times the HVAC system powers ON and OFF
  • Increases the life of HVAC Systems
  • Suitable for split type central HVACs or independent heater and compressor systems
  • Easy Installation either at the thermostat or air handler unit
  • Ability to handle “floating state” of the fan wire when the thermostat is switched off
  • Works in the safe low voltage 24Vac section of the HVAC system


  • Maximum Dimensions (mm) diameter x height: 29 x 15
  • Lead Length: 50mm minimum
  • Stripping Length: 10mm minimum
  • Moisture and Rain Proof : Encapsulated with Epoxy
  • Color: Black
  • Installs on the safe low voltage (24Vac) section of the HVAC System
  • Operating Temperature: -40°C to 85°C
  • Wire Color: White (Heat Input Signal), Yellow (Cool Input Signal), Brown (24Vac Common Line), Red (Ground), Green (Output to the Fan Controller), Gray (Auxiliary Input from the Thermostat) and Purple for compressor bypass wire
Fan Delay
  • 110 seconds minimum
  • 320 seconds maximum
  • The Fan Delay Time is set according to the time that the unit has been turned on (Software installed inside the CWS HVAC Chip)
  • Common Wire: Connects to the 24 VAC at the thermostat or air handler unit
  • Power Wire: Connects to the power line at the thermostat or air handler unit
  • Cooling Wire: Connects to the wire which controls the compressor (AC) at the thermostat or air handler unit
  • Heating Wire: Connects to the wire which controls the heater source (AC) at the thermostat or air handler unit
  • Fan Wire: Controls the ventilation fan of the HVAC system. When the CWS HVAC Chip is installed, it controls the ventilation fan (thermostat will no longer have control over the ventilation fan). The installation sheets show how to make the connections
  • Auxiliary Wire: Regardless where the CWS HVAC Chip is installed (thermostat or air handler unit ), this wire receives signals from the thermostat fan control (green wire). See installation sheets
  • Auxiliary Wire: Regardless where the CWS HVAC Chip is installed (thermostat or air handler unit ), this wire connects directly to the HVAC compressor. The original Yellow wire from the thermostat now gets connected the CWS HVAC Chip’s Yellow wire. See www.hvac-chip installation sheets of CWS-8THEM-0006


A typical HVAC consists of heating unit, air conditioning unit and the ventilation fan or blower at the air handler unit. A thermostat is used to control the conditions of the air in a conditioned space by sending control signals to the HVAC furnace or heater, air conditioning and blower fan controller housed in a PCB located at the air handler unit. HVAC fan controller typically operates the ventilation fan for 0 second to 90 seconds after the furnace or air conditioner compressor has been turned off.

Studies have shown that even after this 90 second duration, the furnace surface and the air conditioner cooling coil still has some energy left. This wasted energy is not delivered to the conditioned space when the ventilation fan stops blowing.

There is a need in a HVAC system with a secondary fan controller device (the patent pending CWS HVAC Chip) that can be used to recover additional heating and cooling capacity and operate HVAC equipment at a higher efficiency. In cases where the compressor never shuts down due to very hot outside temperature, water still condenses onto the cooling coils after the compressor has been running for more than 30 minutes continuously, it make sense to shut the compressor down for a few minutes to let the water evaporates away while keeping the fan running.

Operation Principles

The CWS HVAC Chip adjusts the ventilation fan run time automatically for heating based on gas valve activation time or furnace operating time or heat pump activation time. For air conditioning, the same CWS HVAC Chip will adjust fan run time automatically for cooling based on air-conditioning compressor run time. The amount of time the ventilation fan continues to operate after the furnace is turned off or after the air conditional compressor is turned off, varies with the amount of time the furnace or compressor has been running.

The CWS HVAC Chip uses microprocessor and firmware and unique circuitry to achieve this. The furnace’s additional fan run time indicates how much left over heat is stored in the heat exchanger. The air conditioner compressor’s additional run time indicates how much cold water is condensed on the evaporator coil.

The CWS HVAC Chip recovers and delivers more heating and cooling energy to the conditioned space than is possible with original HVAC fan controllers based on thermostat signals.

The CWS HVAC Chip improves the efficiency of HVAC equipment by delivering additional heating or cooling capacity for a small amount of additional electric energy (kWh).

Air conditioners cool conditioned spaces by removing sensible and latent heat from the return air which reduces the supply air temperature and humidity.

Latent heat is removed as water vapor is condensed out of the air due to the temperature of the evaporator coil being less than the return air dew point temperature.

Latent heat is the quantity of heat absorbed or released by air undergoing a change of state, such as water vapor condensing out of the air as water onto a cold evaporator coil or cold water evaporating to water vapor which will cool the air.

Most evaporators are cold and wet (below 40 to 50°F) after the compressor turns off. Cooling energy left on the evaporator coil after the compressor turns off is generally wasted. The evaporator absorbs heat from the attic and cold water on the coil flows down the condensate drain. The CWS HVAC Chip recovers the remaining cooling energy from evaporator coil by operating the fan after the compressor turns off to cool the conditioned space.

Most furnace heat exchangers are still hot (above 135 to 210°F) after the furnace fan turns off. The CWS HVAC Chip recovers the remaining heat energy from the hot furnace heat exchanger after the furnace turns off and delivers this heat to the conditioned space.

The CWS HVAC Chip works by hijacking the fan control signals emitted by the thermostat and replaces it with the new fan control signal emitted by the CWS HVAC Chip itself. In this way, the HVAC fan controller only receives the fan control signals from the CWS HVAC Chip itself and not from the thermostat directly.

CWS HVAC Chip reads the commands from the thermostat and computes the additional ventilation fan run time. The CWS HVAC Chip then sends the adjusted command signal to the HVAC fan controller at the air handler unit requesting it to run for a programmed additional extended time. For the CWS HVAC Chip to work universally, it has to interface with every type of thermostats used in HVAC system. There are many thermostats where the fan output command signal goes into a floating or unknown state when the thermostat is shut off by putting the thermostat switch to system off.

In such a case, if a fan extender device is connected to the thermostat, the fan command signal being in unknown state, could be read in as ON state, and the fan extender device may turn the fan on and run continuously.

However, the CWS HVAC Chip is the only device in the market that is able to read any unknown or floating signals from the thermostat fan command signal and make it as a 24vac or 0vac state. By using the CWS HVAC Chip, the fan will always be turned off even when the green fan line is in float state.

For more technical information, application notes, installation guides and selection charts, please visit www.hvacchip.com.

Are You Ready to Save Money and Energy?

Disclaimer: Coil Winding Specialist, Inc., its affiliates, agents, and employees acting on behalf of Coil Winding Specialist, Inc. (collectively, “CWS”) disclaim any and all liability for any errors, inaccuracies or incompleteness contained herein or in any other disclosure relating to any product. CWS reserves the right at any time and from time to time to make changes to design, technical specification, or construction of any product listed on this website without notice. CWS also reserves the right to discontinue or limit sale of any product or service available throughout this website on temporary or permanently basis without notice. CWS highly recommends customers not to use its products offered on this website for inappropriate use and applications. Products should be tested for its suitability by prospective customers in all possible applications and conditions. Customers using or selling CWS products for use in other than recommended applications do so entirely at their own risk and agree to fully indemnify CWS from any damages arising or resulting from such use or sale.

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