Masonry Heaters

Also if anyone prefers rocket stoves please explain why, other than initial cost

>>945983
You should always have access ports to clean things even if you never need to use them. You never know when you might need to clear out a bird's nest, scared cat, kid's toys, etc. or even the next owner may have those problems if not you.

>cracking

Make sure everything is fully cured. It may take a few weeks. Keep the mortar properly damp until fully cured and try to make it cure evenly. Meaning do as much of it as fast as you can in as short amount of time as you can. This prevents cold joints which can lead to cracking later on. Once the curing is done, allow a month or more of drying time. You don't want to start a fire in it when it still has too much moisture inside.

> And i read its bad to have more than 3 fires per day? any one know why?

No clue. Perhaps they are overloading them? You can just use a rather small fire normally using dead fall sticks for masonry stoves.

>What exactly makes the firebox burn so much hotter than a normal chimney?

This, like the rocket stove, really depends on proper design. Basically, the updraft draws in tons of fresh air to provide the fire with more oxygen to burn hotter and cleaner. There is a specific ratio for the openings and the length of the chimney to get it to be perfect. Too much or too little of one thing or another and you end up with suet and smoke. No, I do not know the proper ratio. I suggest lots of research and experimentation.

>>945985
I like them and don't like them for the same reasons. Cost and materials. In addition to that, they are extremely limited due to the ratio I mentioned above. Take those rocket stoves in homes that use a 55 gallon drum that has its exhaust snaking through a cob or masonry bench to sit on. That longer pipeline for the exhaust ruins the ratio of the rocket stove. It ends up burner at a lower temperature and you get suet/smoke problems again. Doing it correctly means you'll be venting the heat out of the house where it can't be reclaimed. You'd need some far larger pipe for the flue gases to exit into after a complete burn to prevent the pressure of a longer pipe from stopping the clean burn of the rocket stove. Which is a bit of a bore really. I still love rocket stoves for camping.

However, a masonry stove essentially takes care of this problem. They are however very difficult to calculate correctly. Design it incorrectly and it won't work for heating and/or smoke removal. This is one reason they fell out of favor. They are a bit of an art to get right.