Experience the Horizon difference! Horizon Services is the region's largest and most well-respected plumbing, heating and air conditioning company, with nearly 600 employees serving tens of thousands of homeowners throughout Delaware, Southeastern Pennsylvania, Southern New Jersey, and Northeastern Maryland. After a quarter of a century in business, Horizons Services remains fully committed to setting the industry standard for customer service, installation, and focusing on things that are important to busy homeowners: respect for their time, their home and their property; up-front pricing, and an unconditional 100% money back guarantee.