Purchasers of highly efficient heating, cooling, and water heating equipment can take tax credits of up to 30% of the cost & installation for qualifying equipment, as detailed below. These credits are available for systems placed in service in existing homes from January 1, 2009, through December 31, 2010. There is a $1500 cap on the credit per home, including the amount received for insulation, windows, air and duct sealing.

More information on these tax credits for existing homes can be found at:
http://www.energystar.gov/index.cfm?c=tax_credits.tx_index

And if you're building a new home, you should learn about tax incentives available for your high efficiency installations:
http://www.energystar.gov/index.cfm?c=tax_credits.tx_hm_builders

The Rinnai On Demand Water Heaters are one of qualifying appliances. 
They already save you 40% on your fuel costs because they heat the water only when you use it, instead of keeping a tank-full of water hot 24 hours per day.  And because it heats the water as it's flowing, you will have endless hot water for all of your needs.  Back to back showers for many family members is no problem.  And depending on the model you choose, you can have 2 to 4 uses going on at the same time.
For more information on the tax credits available for Rinnai Water heaters, please visit:
http://www.rinnai.us/tankless-tax-credit/

Please contact Arrowhead LP Gas for more information on any other high efficiency gas appliances that you need.