deciding to do energy star program, or just hvac
I live in NJ. There is a program called njcleanenergy that gives rebates based on the percentage of energy saving achieved by upgrading the hvac and doing other items. Reducing usage by 20% gets a $4k rebate and by 25% gets a 5k rebate. Also, there is 10 year financing at 0% for up to $10k. Our home would get energy star certification. It sounds like a good deal.
I have a 16 year old, 2 story, 2800 sq ft house with a 90% heater and standard (80%?) a/c unit. We want to replace the hvac because many neighbors have been having failures, so we thought to do it while the program above exists.
We had the home energy audit and in order to achieve 20% we would have to go with a hybrid heat/ac system and a power vent hot water heater, along with attic sealing and 6" of insulation. This gets us the 4k rebate. If we do the non-hybrid system with a tankless hot water system and attic work, we get the 5k rebate, and somehow the whole job turns out to be 1k less. We think the tankless option is the best move since it is cheaper.
We had also considered just doing the hvac and not participating in the program. That would cost us $3k less than the whole energy star package, and no special financing. Our water heater is 8.5 years old.
My main question is whether it is worth it to spend the extra 3k on the tankless water heater and the attic sealing and insulation?
The unit quoted is Carrier 59TP5A100E21 and 24ABC648.
Any thoughts on the warranty of 10 years complete vs 5 yr complete w/10 yr mfg part warranty? Are hvac likely to have issues in year 5-10 or do most show up early, and then at the end of life span (sort of like cars). I also read that many of these warranties require you to get them serviced every year. I'm thinking the warranty cost for those additional 5 years, plus the mandatory service fees (rather than getting a friend etc to do it) might pay for any out of warranty repairs.
Any thoughts are appreciated.