You may have heard a complaint or two from a client that seems to be unhappy with their outlet air temperatures at the registers. " With my old furnace, the air coming out was HOT!" or " I dont think the furnace you put in is the right size, the air doesn't feel very hot". 

Its a reasonable concern or question they have, it just requires a little education and explanation is all. Carefully remind them in some way that heat costs money, and the amount of heat NEEDED can save them money at the end of the month. You may also need to educate them on how their new high efficiency equipment is designed and how it works. 

Lets start with space temperature, according to Energystar.gov and utilities across the country (along with manufacture engineers), a recommended thermostat temperature set point is between 68-72*F. If the equipment is sized properly, we can achieve this no problem in the dead of winter. Now lets look at the equipment. Older furnaces (25yrs plus) would have a design temperature rise (difference between supply and return) of upwards to 100*! This means you could potentially see outlet temps of 168-172*F, which is rather unnecessary and a waste of energy (money). Nowadays, due to increasing efficiency standards, and equipment designs, we are seeing design temp-rise numbers topping out at about 60*F. That changes potential air outlet temps to 128-132*F. That extra 40*F is not needed, and costs money. 

Again, if the equipment is sized correctly for the load (home), which is calculated at worst case scenario, we really only need approximately 115-130*F air, to keep us cozy and warm when its zero degrees outside. This keeps money in the homeowners pocket, and can inherently take load off of the energy grids.