Estimate Return on Investment
If you have an idea of how much it will cost to install a new system, use the calculation below to estimate how much money you are likely to save each year with a more efficient system, and what your return on investment is likely to be.
1. Calculate Dollar Savings per $100 of Annual Fuel Cost
To determine savings from the table below, find the horizontal row corresponding to the existing system's annual fuel utilization efficiency (AFUE), then choose the number from that row that is in the vertical column corresponding to the new system's AFUE. That number is the projected dollar savings per hundred dollars of existing fuel bills.
For example, if your present AFUE is 65% and you plan to install a highefficiency system with an AFUE of 90%, then the projected saving is $27 per $100. If, say, your annual fuel bill is $1,300, then the total yearly savings should be about $27 x 13 = $351.
AFUE of New System 
AFUE of existing system 

80% 
85% 
90% 
95% 
50% 
$37 
$41 
$44 
$47 
55% 
$31 
$35 
$38 
$42 
60% 
$25 
$29 
$33 
$37 
65% 
$19 
$23 
$27 
$32 
70% 
$12 
$18 
$22 
$26 
75% 
$6 
$11 
$17 
$21 
80% 

$6 
$11 
$16 
85% 


$6 
$11  
2. Calculate Return on Investment
ROI = first year savings / installed cost
example: ROI = $351 / $2,500 = 0.14 = 14%
