Recently used these guys because my HVAC unit AC wasn’t working (first hot day of summer). Showed up on time, wore booties, fixed the unit. During the visit we talked about how my unit was having problems in the winter – which was resulting in NSTAR service calls of maybe 3-4 times per season (I am on a service plan with them). He was the first guy to tell me WHY the problem was happening, and HOW to fix it. I find it strange that all of the NSTAR guys etc. no one took time to point out how to fix the source of the problem…Very professional, smart. I would use them again, and plan to for the fix on my heating unit!