Todays HVAC systems run more efficiently when they run longer. AMP draw on start up will kill your electric bill. Inverter systems can basically run 24/7 and they use less power than most conventional split systems.
What a professional HVAC company should do is run a load on the house to determine what size system should be used (in the old days, "bigger was always better" does not hold true today with how tight homes can be). There are some generaly guidelines however that tend to hold true as long as you account for windows, building materials that should get you in the ball park per size if need be.
Generally, a two stage gas valve (furnace) and two stage compressor (outdoor AC/HP) tend to do a better job than single stage.
Not disagreeing with anything you said. But time and again I see so many "pros" talk about how terrible it is to oversize a system, both on the internet and in person, and IMO.....I only want to size the system properly.....and they want to grossly undersize it.
Just self-installed my geothermal unit this past spring. Got several quotes from many reputable companies in the area, and full of different options. All my quotes had options for air to air single stage and two stage systems, as well as geothermal single stage and two stage systems.
Based on a comprehensive manual J of my 1250sq ft house + basement, Heating load would be spot on 48k based on 0 degree ambient and 72 degree set. And cooling load was right at 19k based on 95 ambient and 72 set point.
ALL of my quotes were for 2-ton single stage units, and 3-ton 2-stage units as per their recommendations. I told all of them that was unacceptable and design the system based on heating load. And quote me 4-ton prices for both single stage and dual stage. Two of the companies I had to spend 5 minutes trying to convince them why I wanted 4-ton, and then listen to their long-winded BS about dehumidification, and oversized is inefficient, etc etc. Well.....24k BTU heating when I need 48k in the winter requires backup. We dont have Nat gas. And I dont have a propane furnace. So bout the only options for B/U are strips, my current baseboard heaters, or install a propane furnace and tank. Where is the efficiency in getting 1/2 of my heat for the winter out of basebaords or strips???
The third company just flat out refused. They said they would not install a 4-ton unit on my house and declined to quote.
A neighbor (the guy that farms the ~600acres in my area), just built a new house w/geothermal about 10-15 years ago. He has complained about that system since new. Said his electric bills in the winter are outrageous and his backup strips are on all the time. But is happy with the summer preformance. Perfect example of sizing for cooling needs.
Its pretty simple IMO, we have to heat for 6-7 months out of the year here. And only have a ~3 month cooling season. The remainder (like this time of year) dont need anything. 80 degree days and 60 degree nights....nice average of 70. Open the window at night, close during day. Not hard at all to keep the house in the 68-72 comfort range. Heating is my priority. I am not gonna spend 10-15 grand on a system that cannot heat my house without relying on the same inefficient method as my baseboards. So size the darn thing to keep me warm. And in the summer.....if it only runs 10 minutes per hour....and dont dehumidify well.....who cares. 72 degrees at 60% is just as fine with me as 72 @ 35% is.
