When my customers ask how long will it take to pay back for the high efficiency furnace in gas savings, I tell them this.

You can determine your payback time by using your energy bills from the last 12 months. First look at three months during the summer, say June, July, August. Add the 3 months gas bills then divide this by 3. This gives you a average per month amount for the appliances other than the furnace since you do not use the furnace in the summer. Next multiply this average per month number by 12. This is how much you spent on gas for the whole year on every appliance except the furnace. Now add up the 12 months total gas bills and subtract the amount that you figured above for the 12 months of other appliances. This gives you an accurate amount that you spent on just the furnace in gas for an entire year. Now if your furnace is 25 years old it probably has an efficiency rating of 60% AFUE. That means about 60 cents out of every dollar spent on the furnace gas heats the house and 40 cents goes up the chimney. The new high efficiency furnaces are 95% efficient so only 5 cents out of every dollar is wasted out the vent. You can now get bids on new furnaces to check your payback. Say the new furnace costs $2600.00. At the $2600.00 example you can use this to determine the payback. Let us assume a energy bill to use as an example. Say your last years gas bill for just the furnace that you calculated above was $2250.00. This may be a common amount in Minnesota. 95% is 35% more efficient than 60%. $2250.00 multiplied by 35% is $787.50 per year in savings. Using this example the payback would be $2600.00 divided by $787.50 which is 3.30 or about 3 and 1/3 years. Do not forget to take into account the old furnace may break down and the payback would be quicker and how much is peace of mind worth?

If the old furnace is more than 60% AFUE efficiency then just use the efficiency in the calculations. This method eliminates overestimating payback period inorder to give an honest answer.

You can determine your payback time by using your energy bills from the last 12 months. First look at three months during the summer, say June, July, August. Add the 3 months gas bills then divide this by 3. This gives you a average per month amount for the appliances other than the furnace since you do not use the furnace in the summer. Next multiply this average per month number by 12. This is how much you spent on gas for the whole year on every appliance except the furnace. Now add up the 12 months total gas bills and subtract the amount that you figured above for the 12 months of other appliances. This gives you an accurate amount that you spent on just the furnace in gas for an entire year. Now if your furnace is 25 years old it probably has an efficiency rating of 60% AFUE. That means about 60 cents out of every dollar spent on the furnace gas heats the house and 40 cents goes up the chimney. The new high efficiency furnaces are 95% efficient so only 5 cents out of every dollar is wasted out the vent. You can now get bids on new furnaces to check your payback. Say the new furnace costs $2600.00. At the $2600.00 example you can use this to determine the payback. Let us assume a energy bill to use as an example. Say your last years gas bill for just the furnace that you calculated above was $2250.00. This may be a common amount in Minnesota. 95% is 35% more efficient than 60%. $2250.00 multiplied by 35% is $787.50 per year in savings. Using this example the payback would be $2600.00 divided by $787.50 which is 3.30 or about 3 and 1/3 years. Do not forget to take into account the old furnace may break down and the payback would be quicker and how much is peace of mind worth?

If the old furnace is more than 60% AFUE efficiency then just use the efficiency in the calculations. This method eliminates overestimating payback period inorder to give an honest answer.

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