Close Menu

Outdoor Hydronic Heaters

Picture Source: Hearth, Patio and Barbecue Association (HPBA)

Outdoor Hydronic Heaters: General Information and Fact Sheets

Outdoor hydronic heaters (also referred to as outdoor wood boilers or outdoor wood furnaces) are used to heat homes or businesses but they have also been used to heat swimming pools and hot tubs. Indoor wood stoves and fireplaces are not considered outdoor hydronic heaters. In an effort to protect the air you breathe Indiana will regulate the purchase and use of outdoor hydronic heaters, joining other states that have already adopted similar rules.

Emissions from an outdoor hydronic heater can cause air pollution problems when not sited, installed, or operated properly. U.S. EPA has not developed national legislation at this time, but is relying upon voluntary measures and state and local regulation to control emissions from outdoor hydronic heaters. Outdoor hydronic heaters may be regulated by local ordinances.

This website offers information on hydronic heaters in an effort to inform you of the requirements for outdoor hydronic heaters and on Indiana’s rule on the subject.

  • IDEM Fact Sheet, Outdoor Hydronic Heaters (available on the IDEM Fact Sheets page).

Are Outdoor Hydronic Heaters Regulated in Indiana?

Yes, Indiana has adopted 326 IAC 4-3 [PDF] to establish emission limits for new outdoor hydronic heaters. In addition, fuel use restriction, stack height requirements, and a limited summertime operating ban has been adopted for existing units. The effective date of this rule is May 18, 2011. Note: the compliance date for the stack height requirement is November 30, 2011.

The outdoor hydronic heater rule (326 IAC 4-3, LSA #05-332) was adopted by the Indiana Air Pollution Control Board on March 2, 2011. The Indiana Legislative Services Agency provides background information on the rule.

Additionally, IDEM provides an Outdoor Hydronic Heater Rule Fact Sheet (available on the IDEM Fact Sheets page).

Sellers and dealers must provide a copy of the rule (326 IAC 4-3) to buyers and the buyer must sign a notice confirming receipt of the rule. The seller or dealer must send the signed notice to IDEM within 7 days of delivering the unit to the buyer or lessee. Dealers may use the Notice to Buyer form (State Form 53597) to provide notice to IDEM (form available on the IDEM Forms page).

U.S. EPA List of Cleaner Outdoor Hydronic Heaters

U.S. Environmental Protection Agency (U.S. EPA) maintains a list of qualified models of outdoor hydronic heaters that meet the phase 2 emission standards proposed in the draft rulemaking.

Contact Information

For complaints, use IDEM’s Complaints website or call IDEM’S Complaint Coordinator. For general information on the requirements of the rule, please contact the Office of Air Quality.