Have used Dwyer for many, many years. Highly recommend their annual contract for their heating and air conditioner systems.
The technicians sent to my home have always been professional and polite and explained what they did to the system.
One point, though. I had an "after hours" water pipe problem earlier this year -- The pressure controller from the county to the inside of the house blew. If you can turn the water off, do so. Don't call Dwyer for this type of after hours work. The part they used to make the fix - under $100 at Home Depot - Dwyer normally charges $400 for (that's a lot of mark-up); but even worse, when it is an emergency situation - after hours, they increased the cost of the part to $700. Next time I'll turn the water off, go to a hotel and get bids before getting any work done of this sort.