CO2 Heat Pump Water Heater in Madrona Passive HouseCase Study: Published | Updated: | | Seattle, Washington | 0345000125
- Building Type
- non-UL listedsuperior heat pump
- Seattle, Washington
- Maureen Traxler | City of Seattle, Department of Planning and Development
Richard Alford | City of Seattle, Department of Planning and Development
Richard Alford | approving-official
Maureen Traxler | approving-official
Maho Ito | Other
- Ratings & Awards
PHIUS+2015 Certified on 9/13/2016
Seattle’s residential building code requires domestic hot water heating system be tested and listed by a testing agency approved by the State of Washington. in the 1990s, Japanese engineers developed heat pump domestic hot water heaters using CO2, an abundant, natural refrigerant. These systems are known as “Eco-Cute” which means environmentally-friendly hot water because using CO2 avoids conventional synthetic refrigerants which have high global warming potential (GWP). Although Sanden’s Eco-Cute is not yet tested by an approved agency, the City of Seattle’s Innovative Technology Advisory Committee (ITAC) recommends Hammer & Hand be permitted to install the CO2 system as an alternate material because of its superior performance and environmental attributes if it meets four conditions.
Hammer & Hand wants to use the environmentally superior Sanden CO2 refrigerant heat pump water heater system to provide both domestic hot water (DHW) and space heating in constructing a custom Seattle Passive House. The intent of Seattle’s Residential Code is to ensure that materials and equipment such as water heaters are evaluated and certified by third-party organizations approved by the the City. Even though the City requires third-party testing to the UL standard, and Sanden had not yet completed that testing, the SRC recognizes that alternative technologies with equivalent or greater attributes (performance, safety, durability, etc) can be approved by the building officials.
Maureen Traxler, City staff supporting the ITAC, who worked with Hammer and Hand to assist and facilitate the proposal. The written application and subsequent oral powerpoint presentation to the Committee helped establish Sanden’s Eco-Cute’s superior performance and environmental attributes, based on a previous presentation and subsequent approval by to the City of Portland Alternative Technology Advisory Committee (see supporting documents. With twelve (12) members of the ITAC present plus five (5) DPD officials, the meeting included lots of interest, questions and legitimate concerns. A 26-page report listing relevant codes and standards helped guide the 1-hour discussion. The ITAC voted unanimously to recommend the Sanden system on the condition Hammer & Hand supplies the following information: 1. Record of application and timeline for UL Approval; 2. Until UL approval is confirmed, approval by a 3rd party testing agency approved by the State of Washington; and 3. Confirmation of Lead-Free manufacturing and materials per code. ITAC’s recommendation is also conditioned on case-by-case review and approval in the permitting process for each specific building installation.
|Code Requirement||Compliance Path|
|2013 Seattle Residential Code (2012 SRC) section M2005.1: “Domestic electric water heaters shall comply with UL 174.”||Written application to City’s ITAC, ITAC in -person hearing, and ITAC’s conditional recommendation, followed by written building and electrical permit applications based on ITAC’s recommendation.|
|2012 SRC section R104.5||Allows alternate materials and methods|