Is there a big difference between 66,000 and 70,000. I paid for a 70,000 BTU and after the install I looked at the Specs inside the furnace cover and the BTU's are listed at 66,000/58,000 (could be wrong about the lower number but it's close to that). There was a bit of haggling on the price but no mention of installing anything other than 70,000 BTU. My fear is that they went to a cheaper furnace after they agreed to a lower price. Should I be concerned or am I splitting hairs?
Is it a mid-efficient Carrier furnace? I've noticed that, despite have a model number such as 58MCA070, which would denote 70 mbtuh according to how Carrier serial numbers go, they are actually 66 mbtuh or so. Could be the dealer just made a mistake and wrote 70 mbtuh based on the 070 model number designation. No big deal, really, as long as they did a proper heat loss/heat gain (in Canada) or a manual j (what the yanks do), and you're getting the proper output.