This week I was reminded of some unique legislation in Washington State that prohibits the construction of custom masonry heaters.
WAC 173-433-100 requires masonry heaters be emissions tested in order to be sold.
Here is a reference to the WA Dept. of Ecology:
And the specific list of permitted “tested” masonry heaters for WA is here:
https://ecology.wa.gov/getattachment/f558259d-e64e-4255-98c0-94f7b0af05ad/20161010MasonryHeaters.pdf
WA is the only state I know of which requires this certification and the list from 2016 is outdated and contains many models which are no longer even available on the market.
This one-off state approach to custom masonry heater legislation appears to need updating. If they are seeking to harmonize their woodstove legislation with EPA standards then they would do well to also follow it for masonry heaters, which currently offers an exemption for masonry heaters based on their known clean-burning nature, efficiency, and relatively low volume in the marketplace.
I am posting this both to provide information and seek further opinions and experience.