Executive Summary: The Ottawa Rocket Stove Scale is a scoring tool to build better cook stoves by recalling the basics. Watch this short how-to youtube video on how to use it and you can upload the pdf freely below.
As I try to build better diy stoves I look around the internet for inspiration and I see many rocket cook stoves that have missed basics (like an insulated burn chamber) or are built out of materials that will be short lived (such as metal burn chambers). I’ve built a few of these stoves and they do work but are short lived and/or probably not nearly as efficient as the ones originally designed and tested by Larry Winiarski. So I’ve been working on a design tool to get better results.
I wanted an assessment tool that would quickly give me an idea of how well a stove works without lighting it and ideally before I even build it. There are several rapid assessment tools that are used in health care. These help to give a standardized and rather objective score to what would otherwise be a lot of subjective findings. The Glasgow Coma Scale (GCS) is probably the most common of these. It scores a patient’s level of consciousness on a standardized set of criteria. If you’re posting on premies, you’re a 15/15. But if you’ve fallen from an Instructables project and hit your head your score might be much lower. Research has correlated GCS scores to patient outcomes. A GCS score of 8 or less and your chances of survival drop. I’m from Ottawa so I’ll call this tool the“Ottawa Rocket Stove Scale”.
Step 1: Download the Free PDF and Watch the Video
Download the Ottawa Rocket Stove Scale pdf here and print out a few copies. Then watch my short instructional video before moving on to the scoring.
Step 2: Start Scoring Your Stove Design
This tool is for rocket cook stoves, not rocket mass heaters. By following the tool you create a report card for your stove design. Each stove gets a letter grade like in school, so it’s easy to understand. It takes about a minute to score a stove.
Each stove gets points for following Larry Winiarski’s basic principles of rocket stoves. If you’re not familiar with them, you should check them out. http://www.bioenergylists.org/stovesdoc/Still/Roc... There is much more to a rocket stove than an “L” tube!
Tally up each of your points at the bottom of the column.
Step 3: Score Points for Durability and Sustainability
Now move on to the 2nd column and score points based on the materials used. The criteria here are sustainability and durability. Tally up your points at the bottom but ideally you won't have any from this column.
Step 4: Get Your Final Grade
Now you take your tallies from the two columns and subtract the first from the second in the convenient equation. Finally convert your score to the corresponding letter to get your final grade.
Although my stoves work quite well, I've realized that most of them are only D's so there's lots of room to fail better. Check this Grade A stove by the masters themselves at Approvecho.