What is the proper ratio of equipment capacity to load calculations?
Is it really desirable to size the equipment to exactly match the load calculations?
I assume oversizing is more common. What is an acceptable range? 10% oversized?, 50% oversized?
It seems that a system that is sized to exactly meet the load would not have enough capacity to change the temperature of the house fairly quickly - and that seems at odds with how many homeowners want to use their HVAC systems.
For example, at night many people drop the thermostat into the low 60s, or even turn it off completely. In the morning it's cold inside. My neighbors house was 56 yesterday. A system that is sized to match the load, would not be able to raise the temperature to a comfortable range before going to work.
While at work, or on vacation, many homeowner again change the thermostat to keep the HVAC system from running. But again, when returning home, they expect the heat or AC to return the house to a comfortable temperature within a reasonable time (15 to 30 min is my guess).
How do contractor deal with this? Do you try to educate the homeowner, or do you oversize the system?