YPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”> [Updated: May 11] — This easy (“at your own risk”) hack can unlock a Nest thermostat’s “Cool” mode in heater-only installations, allowing control of a heater’s ventilation fan as though it’s an A/C. The Nest Learning Thermostat is a terrific energy saving Linux gizmo, with lots of cool features. I’ve been using one since January of 2016, and have enjoyed its ability to adjust our home’s heating based on an extensive array of time and temperature set-points. One frustration, however, is its inability to control our central heating system’s ventilation fan in a non-heating mode to circulate air in warmer weather using the same scheduling features that the Nest provides for heating or A/C cooling control. Not all homes have — or even need — air conditioning. For example where I live, in Silicon Valley, our temperatures tend to be moderate throughout the year, with occasional heat waves. Additionally, my house is well insulated by virtue of its wood shake roof, stucco exterior walls, and lathe-and-plaster interior walls. Consequently, in the ...