HVAC specialists and salesmen of all calibers were pushing economizers onto the population since they've been invented, with close to zero success. Don't know about you, but I haven't met a single person in my life that uses it, and believe me, I'm asking just about everyone I meet.
There is a very good reason for that - it is difficult to make an average person to part with quite significant sum of money unless they're convinced it's for their good. And you absolutely can't convince anyone without cold, hard numbers in your hands. And, surprisingly, the art of HVAC sales and installation is very far from numbers.
Not so here.
Image above (click to enlarge) represents 22 hours of indoor and outdoor temperature for February 14 2010. Here's a summary:
- For 18 hours, heating is required;
- For 7.5 hours, outdoor temperature is above indoor temperature while indoor temperature is below the setpoint;
- That is a whopping 39%. Thirty nine percent.
When does it make senseThe wider is your daily temperature range, the more are the chances that you will gain a very significant financial benefit from running an economizer (keep in mind that it is cheaper to run it tan to run a heater or A/C - it is essentially a fan).
It also makes a lot of sense if you're running a home office (computers generate a lot of heat), have a home theater (TVs and amplifiers generate a lot of heat, so do people watching the movies and listening to the music), and, of course, if you have a kitchen. Wait, don't you have a kitchen?
How to see it for yourselfEveryone's location, climate and conditions are different, and you need to use your data in order to make a decision on whether you do or don't need an economizer.
For now, you'll have to exercise some amount of RRDGraph magic - you already ave all the data necessary (prvided you have the outdoor temperature sensor, of course).
But wait, there's more...
<to be continued>