I just had a Amana AMV9 2 stage varible speed furnace installed today. All the work looks very well done except they installed a single stage thermostat. Doesn't this defeat the purpose of the 2 stage furance?? I wasn't here when the tech finish the installation and my wife had no idea was to look for. The salesman didn't give me any thermostat choices when I got the estimate. Should I request that they install a 2 stage thermostat??