First and foremost some companies will put their service techs on commission selling new product. They are trained more in sales than in service. Rather than the first goal is to fix what is wrong their mission is to sell you something with a big price tag to earn a nice commission. If your existing system is more than let say 10 years old they will automatically try to sell you something. Service techs are employed by us to fix and repair whatever is wrong. If the repair is going to be very costly they can recommend and ballpark new equipment but there is no commission involved to the service tech. Unfortunately I see way to many companies putting their techs on sales commission. Sometimes this will lead to some unscrupulous behavior. I would always recommend if a service tech trying to make a sale that you get a second opinion. Caveat emptor or Buyer Beware!
The HVAC equipment made in the last fifteen years or so has more bells and whistles. To get the desired energy savings compared to what was made in the 1960’s and 1970’s there are more parts. Because of this I would recommend having a maintenance contract with your HVAC provider. This will prolong your equipment life and keep it running to take advantage of the higher energy savings features. Just like you have your car serviced.
The most efficient equipment is sometimes not the best buy. Most manufacturers will try to get the dealers to sell the most efficient equipment because there is more profit in it and other added benefits for the dealer. In the Good, viagra Better, Best scenario many times the Better equipment is what is right for you. It all depends on how look you will be living in house, the differences in price and what your budget can afford.
If you are looking for service always check the dealers Better Business ratings and Reviews or you can check their Google reviews.