I used CoreTemp to proactively replace my 16 year old furnace and AC for a couple of reasons:
1. He was recommended by my father who used them to replace his furnace and AC earlier in the year and was very satisfied.
2. I had an issue with my furnace a couple of years ago and Richard helped me diagnose the issue over the phone even though he did not service my make of furnace. I appreciated his willingness to help even though he wouldn't be getting the business of doing the repair.
My experience with CoreTemp is that their prices were reasonable and Richard took the time to explain the options based on my needs and did not try to upsell me. The installation by Richard and Eric was clean and thorough (they definitely don't cut any corners) and the equipment has worked perfectly ever since. It was also great that the crew is very personable.
I plan to use them to maintain the equipment as they will extend the labour warranty while it's annually maintained by them. Their annual maintenance was reasonable too ... cheaper than other companies I had used before.