If you’re replacing a furnace, it probably means that you are getting hit for a big cash outlay, and you may be easy prey for anyone offering a time-limited “special”. The best approach is to realise that this situation offers an opportunity to upgrade the energy efficiency of your home, and then get a smaller–and hopefully less expensive–furnace. Start by getting an energy evaluation of your home performed (contact Natural Resources Canada or your local utility) and fixing the major energy leaks. Now you can save some bucks on the furnace replacement!
Don’t forget to look at items like topping up attic insulation and shading the south-facing windows–these items will cut the home’s need for summer cooling. You may also be able to increase your home’s resale value by showing your lower utility energy bills to prospective home buyers!