Lower Your Electric Bill With CooLBot

By Jude Boucher, UConn Cooperative Extension

Last summer a CT grower showed me the small garage that he super-insulated with foam board and was using as a walk-in cooler.  To cool the space down to 35 degrees F he was using one or two standard air conditioners (depending upon how hot it was outside) that were controlled by a CooLBot.  The CooLBot cycles the conditioner units on and off to avoid freeze-up so that they can cool a room far below the standard 60 degrees that units are pre-programmed to shut off at.  He said he had saved over $500 per month on his electric bill by switching to this system from his old walk-in cooler compressor, and that was after adding central air to his house at the same time. He was looking forward to saving even more because he would no longer have expensive repair bills for the old compressor.  I checked in with him again at the end of the season and the new system worked well all year for him and saved him a small fortune.

If you want to find out more about the CooLBot go to www.storeitcold.com or search for the web site under CooLBot.  This robot was invented by a NY farmer in his quest for a cheaper way to cool his produce.  On his web site he has notes on how to build an inexpensive walk-in cooler; hints on post-harvest vegetable care with temperature requirements for individual crops, CooLBot installation instructions/video, suggestions for air conditioner brands/sizes to match room sizes, and the limitations of what CooLBot can and can’t do.  The installation is incredibly easy…here are his pitch and installation instructions – but check out the video:

The CooLBot turns any brand of off-the-shelf, window-type air conditioning unit (purchased separately) into a turbo-charged cooling machine.  With it, you can transform a highly-insulated room into a walk-in cooler, keeping your vegetables fresh and thermostatically controlled cool down to 34 degrees F!
CooLBot will not only save you on installation and repair costs, it will also help you save electrically, reducing your operating costs when combined with new Energy Star air conditioning units engineered to much stricter environmental standards than standard walk-in cooler compressors.  CooLBot uses new (patent pending) technology that just became available in 2006.

Performance varies based on the size of your room and the size of the A/C unit you have.  As a guide:  Here in Southern New York, a $300 Home Depot 18,000 BTU window A/C unit kept produce in a 7’ x 12’ insulated room at the 38 degrees F we set it to during the summer with plenty of cooling power to spare.

  1. Install any brand of window A/C unit which you’ve purchased separately.  (See the table below for sizing).  We just cut a sloppy hole in the wall of our home-built walk-in cooler with a chain saw, stuffed the A/C unit into the hole, and then “Great Stuff” foam sealant to seal up the gaps.
  2. Plug the CooLBot into a standard A/C outlet – it uses no more electricity to run a cell-phone charger, so no special electrical connections are needed.
  3. There are three labeled wires coming out of CooLBot: one measures the temperature of the room, just let it hang free.
  4. The second wire (labeled frost sensor) you stick into the cooling vent fins of the A/C unit.  It holds there on its own, you don’t need tape or screws or anything.
  5. Attach the third wire to the temperature sensor you see sticking out of the front of your A/C unit.  (It’s the only thing you’ll see attached to the front fins of your A/C unit.  Sometimes it’s black with a little bulbous end…sometimes white with a little bulbous end…  Just wrap the CooLBot wire and the end of the temperature sensor together using a small ½ inch by 1 inch piece of aluminum foil to ensure a good thermal connection.
  6. There are three buttons on the CooLBot – Set the first one (labeled room temperature) to your desired temperature (between 33-60 degrees F).

That’s really all there is to it!

You should be finished in 2-3 minutes and be seeing results below your A/C units’ normal capabilities within 10-15 minutes after that!  The time it takes to reach your desired temperature obviously depends…someone in AZ with a starting ambient temperature of 109 and an un-insulated (109 degree) concrete floor is going to take longer than someone in NY with an ambient temperature of 85 and an insulated floor!

If you follow our specifications (below) EVERYONE will be able to reach their desired temperatures (we even have people using CooLBots in Dubai this year!  Heat is NOT a problem.  No permanent modifications are made to the A/C units.

Room size to A/C ration for rooms that are insulated to industry standard 4” solid Styrofoam floor/walls/ceiling and cooling to 35 degrees F.
Florists and Convenience stores using glass display doors should call for adjusted sizing recommendations.

Dimensions of Cooler  Size of A/C Unit
6’ x 8’ 10,000 BTU
8’ x 8’ 12,000 BTU
8’ x 10’ 15,000 BTU
8’ x 12 18,000 BTU
10’ x 12 21,000 BTU
10’ x 14’ 25,000 BTU
A/C capacity versus room size