Coupons$200 off when you have us install a new furnace and air conditioning system or a furnace and heat pump. This coupon is not to be combined with other offers, discounts or coupons, other than those outlined on your official DeLong Air System Estimate. $20 off coupon the next time you need us for a service call. This coupon cannot be combined with other offers, discounts, or coupons. This coupon cannot be used with the Smart Homeowner Club Membership.