• "EF" means energy factor (dimensionless).
  
• "E" means electrically operated system.
  
• "NG/P" means natural-gas- or propane-fired system.
  
• Water heaters (WH) are categorized into four tax credit tiers depending on their performance:
  

Tier WHE1 - savings of 1000 kilowatt-hours - $400 tax credit amount
Tier WHE2 - savings of 1,395 kilowatt hours - $560 tax credit amount
Tier WHG1/P - savings of 45 therms - $215 tax credit amount
Tier WHG2/P - savings of 71 therms - $340 tax credit amount

• Tax credit amounts may be limited by the "25 percent of net cost" maximum (see information pages).
  
• Savings are in kilowatt-hours for electric units, therms for natural gas or propane-fired units.
  
• Level WHE2 assumes a ducted installation, set up to use the home´s exhaust air stream, or other pre-heated air, as the energy source. Level WHE1 assumes the unit uses ambient air as a heat source.
  
• All electric models are heat pumps.
  
• For instantaneous units used in a storage mode, with one or more storage tanks, storage must be insulated to a nominal R-16. Tanks without equivalent bottom or top insulation must be installed with bottom boards, whether indoors or out.
  
• Installation costs in excess of those associated with a conventional water heater can be used when computing the maximum tax credit amount (maximum of tax credit shown versus 25 percent of the net cost).
  
• Qualifying tankless water heaters must have a variable firing rate between no more than 24,000 BTU and at least 140,000 BTU.
  
• Electric water heaters must have a COP of at least 100%
  
• Conventional tank-type water heaters are not efficient enough to qualify for a tax credit.
   
   For more information, contact us at (503) 378-4040 in the Salem area or (800) 221-8035 toll free in Oregon. We can also be reached via email at energyweb.incoming@state.or.us.