Knock $4,000 off your utility bill
Invest $1,500 in insulation and maintenance and get over twice that in energy savings the first year.
Cost: $100 to $200 per unit a year
Payback: $300 to $500 a year
Cleaning your furnace's oil burners or removing scale from gas units, changing filters and checking refrigerant levels in the air-conditioning system are not exactly do-it-yourself jobs. You'll need some help from the professionals.
For every year that you fail to schedule service for your furnace (gas or oil), you'll wind up using 5% more heating fuel because of all the gunky buildup, and you'll pay 10% to 30% extra for neglecting your central air conditioning.
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