I was going to buy a Mad Dawg heater but found a good deal on a near new heat and air unit. It cost about $100 more than the Mad Dawg and I have air conditioning too. The duct work was about $400 including the programmable thermostat.My shop is 36' X 54' with 12' walls and no ceiling, it is insulated and I have a fan pushing the warm air down from the attic space. The thermostat is set on 50*, when I go out to work I raise it to 55*.