Equipment

Be sure to match the “SEER” rating of a heating unit or “EF” of a domestic hot water heater to the values that were modeled in your preliminary HERS rating. If changes are being made, be sure to contact us so we can update the model and head off any potential problems at final commissioning.

Changes between fuel source and/or efficiency rating can greatly impact the HERS rating.

Sealed Combustion Water Heater or Boiler

  • Pulls combustion air from outside, not indoors.
  • Not affected much by pressure changes.
  • Preferred for energy-efficient homes..

Naturally Drafting Oil Burner

  • Uses natural convection to vent exhaust.
  • Can backdraft from exhaust fans or poor air sealing.
  • Needs proper make-up air planning.

Naturally Drafting Flue

  • Includes boilers, furnaces, fireplaces, wood stoves.
  • Draws air from inside rather than sealed intake.
  • Higher backdraft risk in tight homes.

Mechanically Vented Water Heater

  • Uses a fan to push exhaust outside.
  • Less affected by indoor pressure changes.
  • Generally safer in tight homes.

Naturally Drafting Water Heater Hood

  • Relies on natural upward airflow to vent gases.
  • More prone to backdrafting in airtight homes.
  • Typically not recommended for new construction.