Location: Federal Way, WA - Western Washington (Zone 8 - temperate maritime)
posted 5 years ago
I know there is no comparison in terms of price and DIY, but I am wondering if a rocket stove can be legally vented right through the wall, as the zero clearance wood burning Rumford style fireplaces apparently do. Also, any other comments on this, and other, zero clearance wood burning fireplaces? Thanks for everything, btw - 'praying' for Eric's healing :)
It's time to get positive about negative thinking -Art Donnelly
The legal and practical requirements for venting a rocket mass heater vary greatly with the location. Some areas (like Vermont) there are no requirements regarding residential installations, and careful siting to the downwind side would allow a side-vent. Some valleys, like the Cob Cottage enclave in Coquille OR, offer mild and predictable winds, and a sheltered side for unconventional vents or chimneys.
Still, many areas don't offer a predictable 'downwind' side, and so other measures might be needed to ensure adequate draft with a side vent. We've also seen strong winds cause eddies around the corners of a building even on the downwind side, and tall or leaky buildings that create 'negative pressure' and cause low vents to draw backwards into the home.
In general, I regard side vents as experimental. They often take a lot more 'tinkering,' and sometimes end up requiring much more expensive materials and awkward supports to get them to work properly.
In cases where it's important for the heater to work well from the moment of installation, I recommend a relatively conventional chimney. I sometimes compromise with an installation that allows for retrofitting such a chimney at a later date (such as an upward-pointing cleanout prior to exiting the wall, so the cleanout and vent could be swapped later if needed).