1) Just because the equipment is older does not make it a good reason to replace it. If a furnace or air conditioner are working well and have not had multiple failures, it may not be the time to replace.
2) If you are not sure your furnace or air conditioner is in good shape and worth keeping, consider having it checked over by a professional, licensed mechanic of your choice. They should use a systematic checklist to explain how your system is working and whether there are any problems with it.
3) If you are looking to invest in new equipment to increase the efficiency of the furnace or air conditioner look at the cost to upgrade versus the savings available. ie: "payback time".
eg: A very old air conditioner may have been 7 SEER (Seasonal Energy Efficiency Ratio) efficient, whereas a top of the line new air conditioner can be 21 SEER. That's "3 times less hydro used" . Also, think of the length of time it is used yearly. A very old furnace may have been 65% efficient, whereas a top of the line new furnace can be 97.7% efficient in gas consumption and be electrically efficient also.
Gas efficiency 97% - 65% = 32% savings.
DC motor 80% - 20% regular motor = 60% savings.
4) Selling your home?
More and more buyers are investigating the major equipment in a home before purchasing.
The type of equipment can affect the homes resale value. However, keep in mind the cost of these possible changes and the effect they would have on the pricing of your home sale.
5) Many older systems work fine and can give you years of further use. Buy because you have to, or because you want to, not because someone scares you into a sale. Consult a long time, reputable, local contractor of your choice for advice.
6) A new furnace or air conditioner can be installed when needed in one day.
7) Commissioned salespersons may be quicker to recommend replacement. We do not pay commission to any staff!