When New Mexico winters hit, everyone's natural gas and propane bills go up. Our heating services get busy and we work on furnaces that range from 10 to 50 years old. The furnaces that are 80% are probably just fine the way they are as long as a carbon monoxide test is performed. The best way to tell if a furnace is at least 80% efficient is to look at the furnace vent and see if it has a motor called an inducer motor.
The average installation cost right now for heating services installation at Custom-Air is $1600.00. That includes the furnace, a new programmable thermostat and labor. The return on investment is usually a few years and then you get the installation cost back. It comes back faster in years that the natural/propane gas prices are higher.
The 90% variety furnaces are a little more complicated! First, the actual cost of these furnaces are almost double the the cost of the 80%. Second, the installation cost goes up due to special PVC venting and condensation removal plumbing. We install 90% furnaces mostly in the East Mountains and Placitas where the return on investment is at least a possibility.
A very good option available is the two-stage furnace. The first stage heats up the home or business and the second maintains the heat. Only a couple of hundred dollars difference, they are a good fit for many homes. For homes with existing duct issues, the option of a variable speed furnace could help air-flow to rooms with problems. Many new construction contractors cut cost by having the lowest heating and air conditioning bid do the work. Unfortunately, the duct system suffers in the decision. That's where a variable speed furnace may be able to help. Also, caught up in the decision for low bid acceptance is the sizing of the furnace and air conditioner. If the system cycles on and off prematurely it is probably sized wrong. Always invest in a carbon monoxide detector for your home.