Green It

Votes: 1
Views: 950

The mission of this device is energy savings. I call it Green It, but any name can be applied. It's designed to detect and report common and sometimes costly failures when added to an HVAC system installed in most homes and small businesses.

Current state of the art in HVAC systems provides a building with heated air, cooled are or air circulation. Problems arise when the HVAC system is not running efficiently. Low Freon can cause the system to run longer than necessary and causes ice to build up. This blocks air flow. The system runs longer and the cooled air does not reach the working / living space. When the ice melts (see photo) it makes a damp condition in the walls of a home that termites need, along with wood to survive.

Damage to hardwood floors and ceilings can also be the result. A clogged filter can cause this icing too. An outside unit that keeps running (due to a stuck relay) will be reported. A failing compressor can be reported if Freon is low or if an expected temperature of a running system is not realized.

In winter months when the Heat Pump is in use the system might fail to defrost itself. This causes icing (see photo) of the outside unit and unless noticed by the homeowner this unit will run and not heat the home or business efficiently. Most systems have back up electric heat strips. They'll run up an electric bill and it's a surprise to most homeowners that have a failure like this. The power companies know this well as most checked electric meters are operating correctly.

All of these failing conditions can be detected and reported with this device. Adding a Green It to an installed HVAC system will report failures to the occupants. Additionally, the manufacturer of the HVAC system could incorporate this device into their system during the manufacturing process.

I've built 23 of these devices using off the shelf plastic enclosures, fasteners and electrical components. I used PC boards with .100" pin spacing. Surface mount components will reduce the costs to produce each one. No special manufacturing techniques are required. Any HVAC system can benefit from this device, even if only an Air Conditioner, or up to a Heat Pump with 2 stage heating.

The Green It gets its power from the HVAC system. The microprocessor takes inputs from a temperature sensor attached to a copper pipe between the inside and outside units, a voltage sensor for the compressor control wire and a switch to enter service mode. A program sets up timing and reads these inputs to determine the correction function of the attached HVAC system or when things go awry. At that point conditions can be reported by an LED or audible alert. One other output is through an N/C connection of a relay to prevent short cycling of the compressor or suspend its operation when a frozen condition is detected.



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  • Name:
    Tom Buckley
  • Type of entry:
  • Profession:
    Electronics Hobbyist
  • Number of times previously entering contest:
  • Tom's favorite design and analysis tools:
    Microchip MPLAB, Microsoft Paintbrush
  • Tom's hobbies and activities:
    Electronics, programming micro-controllers, etc.
  • Tom belongs to these online communities:
    None at this time.
  • Tom is inspired by:
    To solve a problem with a product or create a new one that needs to be on the market. Especially where saving energy is involved. Sometimes just for my own home.
  • Software used for this entry:
    Microchip MPLAB
  • Patent status: