Win a copy of For the Love of Paw Paws this week in the Fruit Trees forum!
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
permaculture forums growies critters building homesteading energy monies kitchen purity ungarbage community wilderness fiber arts art permaculture artisans regional education experiences global resources the cider press projects digital market permies.com private forums all forums
this forum made possible by our volunteer staff, including ...
master stewards:
  • Nicole Alderman
  • r ranson
  • Anne Miller
  • paul wheaton
stewards:
  • Jocelyn Campbell
  • Mike Jay Haasl
  • Burra Maluca
garden masters:
  • James Freyr
  • Joylynn Hardesty
  • Steve Thorn
  • Greg Martin
gardeners:
  • Carla Burke
  • Dave Burton
  • Pearl Sutton

Heat Riser Insulation Nececessary

 
Posts: 3
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi. I am designing a rocket stove thermal mass heater as an insert in my fireplace. From what I have gained from online research, the burn chamber (flue) is always insulated, reason cited is that you want the thing to be hot. My observation is this: it seems it would get even hotter if it was NOT insulated.

Must it be insulated to work and why?
 
gardener
Posts: 3086
Location: Southern alps, on the French side of the french /italian border 5000ft elevation
135
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Doug, read, read and re read, untill you understand things. Order the book of Ianto too. It's clearly explained. I will only say a word, heatsink!
 
Doug Nevill
Posts: 3
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Satamax Antone wrote:Doug, read, read and re read, untill you understand things. Order the book of Ianto too. It's clearly explained. I will only say a word, heatsink!


What do you suggest that I read? If you have read the "book of Ianto", does it answer my question - MUST the heat riser / burn chamber / combustion chamber (inside pipe) be insulated or not?
 
Posts: 148
1
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
As a starter for where to look, and what to look for, this has been covered many times.

The principle of the rocket heater is that you burn fuel at high temperature for as long as possible. To get the temperature, you need not to lose heat from the flame, hence the insulation. Now here's the clever, and important bit, when the gases get to the barrel having been got as hot as possible, and having got up the riser driven by the heat, they get cooled by contact with the barrel. As they lose heat and fall in temperature, they drop down the barrel. This is the other half of the heat pump. The heat riser, does what it says on the tin, and makes the gases rise. The barrel cools them and makes them fall down the outside of the riser. This is the power that drives the gases out of the flue.

So that you can have hot gases in the riser, and cooler gases (they will still give you a nasty burn) round the outside, you need (you've guessed it) insulation.

This is in Ianto Evan's book and in several places on this and other forums. Understanding this principle and understanding the need for a huge exit hole from the barrel to the flue are the two bits of knowledge without which a rocket stove will fail to perform.

The burn chamber needs insulation to allow the gases to stay as hot as possible. The burn chamber should stay as cool as possible on the outside, so the heat stays inside, achieved by insulating. The barrel is the first point where you extract heat, followed by the flue, where massive heat sinking is needed rather than for insulating.
 
Doug Nevill
Posts: 3
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Roy Clarke wrote:As a starter for where to look, and what to look for, this has been covered many times.

The principle of the rocket heater is that you burn fuel at high temperature for as long as possible. To get the temperature, you need not to lose heat from the flame, hence the insulation. Now here's the clever, and important bit, when the gases get to the barrel having been got as hot as possible, and having got up the riser driven by the heat, they get cooled by contact with the barrel. As they lose heat and fall in temperature, they drop down the barrel. This is the other half of the heat pump. The heat riser, does what it says on the tin, and makes the gases rise. The barrel cools them and makes them fall down the outside of the riser. This is the power that drives the gases out of the flue.

So that you can have hot gases in the riser, and cooler gases (they will still give you a nasty burn) round the outside, you need (you've guessed it) insulation.

This is in Ianto Evan's book and in several places on this and other forums. Understanding this principle and understanding the need for a huge exit hole from the barrel to the flue are the two bits of knowledge without which a rocket stove will fail to perform.



Thanks for the straight answer, Roy.

I'm ordering the book now.

Doug
 
Get out of my mind! Look! A tiny ad!
Heat your home with the twigs that naturally fall of the trees in your yard
http://woodheat.net
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!