Our Certifications at Gillman Heating and Air Our team at Gillman Heating and Air in Perry strives to offer the finest heating and cooling service around. The primary way we keep our expertise and continue to build knowledge about HVAC products is by earning industry certifications. Find out more about the certifications our technicians have received below. SunSource® Solar-Ready Dealer Designation As a Lennox SunSource Solar-Ready Dealer, Gillman Heating and Air has earned Houston County certification requirements for residential solar installations. We’ve gone through training, and we’re knowledgeable not only about the solar-ready Lennox® products we offer in Houston County, but also the area utility requirements, rebates and incentives. We can help make your SunSource Home Energy System installation process quick and easy.