Our contractor used this guy to install our furnace /heatpump it has never worked properly. after waiting a mnth for him to return , he claimed he installed the wrong tstat, second one had the same issue. we called someone else to have a look, they found that the heat pump coil was not mounted in the right spot, nor were there insulating bushings in place to avoid corrosion. They had also installed the furnace in a way we cannot add any air purification. We now know the tstat was not the issue and our second hvac company will have to dig further