like heaght and airconditioning systems. nonsolar water heaters and biomass stoves. must be installed before the ball drops on new year s eve. live from a home depot in atlanta. what are all the restrictions? well, there are quite a few restrictions. first and foremost the units need to be installed in your primary residence. you can t have applied for any of these tax credits before. and if you do get a heating and airconditioning unit, you need to get them purchased and installed up and running by friday, december 31st. and you also need to have certain restrictions. for example, the furnaces need to be 95% effective. the a.c. unit 16 sear at least. and get a certificate from your installer when he or she comes to your house and finish installing those units. also, if you do miss out on this $1,500 tax credit this year. they do expire but next year the government is going to offer a $500 rebate. so, you are in luck if you do miss the application deadline this friday, harris? harr