New AC unit does not appear to be more efficient - How does Sense measure this?


#1

My 23 year old AC unit failed in July and we replaced it with a new unit that was expected to be more efficient. I had my sense system for a while so I know how much energy my old AC unit used and how much energy I used daily in July. After the new AC unit was installed, my energy usage did not drop at all. Something that was expected as AC units are of course the major electricity users in July in Texas and an AC unit from today should be more efficient than one from 23 years ago.

The AC installer and Trane are trying to figure this out and they were wondering how Sense is able to determine the exact energy usage of the AC unit. It is clear to them how the overall usage is being measured but not how the energy usage of just the AC unit is measured. I think they might not trust the Sense readings. Can you clarify what is measure and how?


#2

Does your new AC unit run less than the old one? Does it run at a single speed or variable speed?


#3

The new one is variable speed. I think it runs as often as the old one. But even if it runs less, the overall energy usage is the same.


#4

There’s something weird here. Variable speed compressors are very difficult to detect. So I’m amazed that Sense accurately picked it up.


#5

A new 10,000 BTUh A/C replacing an old 5000 BTUh unit would be 50% more efficient if it drew the same amount of power as the old unit…


#6

It should be, but it doesnt look like it is. After further investigation, I found that the blower motor inside uses about 400W when it runs while the outside fan uses 2,500 W.


#7

What was the BTUh rating of the previous air conditioner?
What is the BTUh rating of the replacement air conditioner?