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How to Set up a Winter Cool Room with CoolBot® + Inkbird

How to keep a CoolBot walk-in cooler above freezing in winter with a plug-in thermostat and a small heater, for root crops, bulbs and more.
By Hensley’s Seed Co.
Coolbot in a cool room

How to Set up a Winter Cool Room

CoolBot® + Inkbird + Space Heater  =  21st-Century Root Cellar

When winter comes, many small farms and gardeners wish they had more space that stays cool without freezing.

This setup covers many cool-storage needs: extending the storage life of fall root crops, prechilling spring bulbs such as tulips and daffodils, holding tender perennials like begonias, dahlias and gladiolus over winter, forcing Belgian endive and more. A winter cool room can turn out to be surprisingly useful.

Winter Goal: Keeping Perishables Cool… Not Frozen

Monitor and control cool-room temps remotely with the CoolBot Pro
A CoolBot is one of the pieces you'll need for a cool room.

Here are directions for building a CoolBot walk-in cooler on a small farm.

No root cellar? Build a walk-in cooler run by a CoolBot, then add a controller to manage the temperature inside once outdoor temperatures drop below freezing.

3 Components to the System

Start with a walk-in cooler and CoolBot set up in a suitable space. Then add two more components to reach the winter goal: keep the cooler above freezing but below the CoolBot's set point. Do this by plugging an ordinary convection space heater (NOT a radiant heater) into a thermostat-controlled extension cord. (See options below.) The main advantage over a traditional root cellar is that you can set and hold the exact temperature you need more precisely.

  1. CoolBot: a controller with several sensors and a programmed microchip that works with a standard off-the-shelf digital window air conditioner to do the job of a much pricier commercial walk-in cooling unit. It comes in two models:
    • Original CoolBot
    • CoolBot Pro with WiFi
  2. Plug-in thermostats that work:
  3. Sample convection or ceramic space heaters:
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Step-by-Step Set-up

Here's how to set things up so the walk-in stays above freezing in the coldest months, between 32°F/0°C and your CoolBot set temperature.

  • Keep the Inkbird set point at least 4°F apart from the CoolBot set point so the two never overlap and fight each other.
  • Leave your usual air conditioner and CoolBot setup in place and plugged in.
  • Plug in the Inkbird controller.
  • The Inkbird reads in Celsius out of the box. Switch it to Fahrenheit if you like, following the Inkbird manual.
  • Put the Inkbird sensor right next to the CoolBot's ROOM sensor and give both a few minutes to settle.
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  • If the Inkbird reading (the top number, PV) doesn't match the CoolBot display, adjust the Inkbird's temperature calibration (CA) as described in its manual. Aim for the two readings to agree within about 1°F.
  • Set the Inkbird's set value (SV) to 34°F/1.1°C using the manual's instructions.
  • Set the Inkbird's heating differential (Hd) to 2°F/1°C using the manual's instructions.
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  • With everything set correctly, the Inkbird should show:
  1. PV: within about 1°F of the CoolBot reading
  2. SV: 34°F (in Fahrenheit mode)
  3. 2°F (in Fahrenheit mode) when you press the UP arrow to view the heating differential
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  • Plug the heater into the Inkbird outlet marked HEATING. Leave the COOLING outlet empty (do NOT plug the CoolBot or air conditioner into it).
  • Switch the heater ON and set it to Low.
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Note: These heaters are efficient, and a small one can heat a big room. As a rule of thumb, size the heater at about 10 watts per square foot of floor. A 100-sq-ft room, for example, needs about a 1,000-watt heater. If yours is rated 1,200 or 1,500 watts, run it on Medium or Low (NOT High), because the Inkbird cord can't carry the full load.

THAT'S IT! Check that the system works as expected and fine-tune as needed.

Based on the manufacturers' setup instructions; setup images courtesy of the manufacturer. All rights reserved.
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