Outstanding service and experience! We have a 14 year old boiler system and had had a couple of other companies check it out in the last 3 years since we bought the house. None of them really seemed to understand the boiler/infloor heating system and correct what to us, were issues in performance and operation. Mark knows his stuff – we called him due to a leak from the expansion tank/safety valve line in the hot water/boiler system, after doing some research on line for speciality companies, as I didn’t want the same old story. He quickly returned my call, and set up an appointment – even offering to come over that evening. Within a few minutes of inspection, he found several issues with the boiler, ductwork and water supply system, and was able to explain to me the issue and the fix options (as well as the implications of the issues for performance and safety). After completing a thorough inspection with Julian, he then provided an estimate with and explanation of what was needed, and we agreed on the scope of work. It was a relief to meet professionals who are knowledgeable in this type of system. Julian, a great journeyman, completed the work with excellent quality, and obvious pride in his craft, which included reprogramming the system to eliminate wasteful water pumping/recycle. They took care of the worksite as well. Drop clothes were used to protect our floors and the house was left clean and neat, including the furnace room where they drained and flushed the boiler and in floor piping systems. Mark and Julian took the time to explain all we needed to know about routine maintenance and operation of the equipment and ensured we where happy with the end result. DHL is the only mechanical company I will use for future boiler maintenance. Great experience, top quality craftsmanship, friendly and personable! I highly recommend them.