The current Ecobee put in works by using the PEK mainly because I do think there are only four or 5 wires likely in the thermostat towards the furnace but I am able to rather easily add extra wires if necessary to get two stages (thermostat is sort of directly https://copyright-side-effects49481.blogthisbiz.com/42692783/5-simple-statements-about-copyright-side-effects-explained