Want a warm toasty house through those long winter months?
Do you love entertaining outside next to a warm, welcoming fire or cooking on a barbeque?
How about relaxing in your wood-heated outdoor hot-tub for those starry nights?
We can help you do all these things,
better and cleaner than ever before
Rocket heaters are the smart, safe and sustainable alternative to a standard combustion heater. A rocket heater uses 50-90% less wood than a combustion heater and also the emissions are said to be 100 times lower than a combustion heater. These numbers can be very hard for people to grasp or often simply don't believe the numbers but to understand, you need to understand that rocket heaters are a completely different beast to a combustion heater. A rocket heater encompasses rocket mass heaters and rocket stoves. Rocket stoves are cooking devices used exclusively outdoors. There is some confusion as Americans will often refer to "stoves" when they mean a heating device. This has confused people over the years that think a rocket stove and rocket mass heater are different when it's just what Americans call a heater...a stove
Rocket Mass Heater in a Tipi
This was an experimental project in Missoula Montanna (Just South of Canada).
The idea was to build a RH in a structure with little to no insulation and see how people would live through a Northern American mountain climate winter.
They were quite comfortable. There is a full article on The "Permies forum" which you can read here.
Combustion heater efficiency
Let's start with the efficiency of a combustion heater. Combustion heaters are sold these days with an efficiency rating either in a percentage or a star rating. This rating comes from a number that was created in a lab. When these heaters are operating at high efficiency (which they can), most of the heat goes out of the chimney. The reality is that when Combustion heaters are operated in homes, the efficiency drops significantly in an attempt for the occupants to enjoy the warmth for longer and reduce their wood consumption. The occupants are operating the Combustion heaters "effectively" but not efficiently. Unfortunately, this causes the Combustion heater to smoke (smoke is unburnt fuel) and wood smoke contains hydrogen cyanide, methane, formaldehyde, benzene and carbon monoxide.
Rocket heater efficiency
Rocket heaters are so much more efficient than combustion heaters because of several design factors. Rocket heaters are built from either firebrick or other refractory materials which so we can create a much much hotter fire and utilise much drier wood than a metal combustion heater can handle (the metal will oxidise and flake off (called spalling which has the appearance of rust).
With a hotter fire and drier wood, more of the fuel is burnt and there is little to no smoke.
The design of the rocket heater only allows the tips of the wood to burn (like how a match would burn) so the wood only burns when it is required.
The burn tunnel of a rocket heater causes a large amount of turbulence making the gasses swirl, reignite and burn almost completely.
Once the wood from a rocket heater has been burnt, all that remains is heated air. That hot air is then sent into thermal mass chambers which extracts the heat. The thermal mass slowly extracts the heat and stores it until the thermal mass is saturated with heat and will then release it to the surrounding air.
A rocket heater can heat a space for 8-24 hours after the fire goes out. Because the thermal mass extracts so much heat from the heated air, the remaining air that leaves through the chimney it relatively cool (compared to a combustion heater) and often to the point where you can comfortably touch the chimney without getting burnt. There are no reasons to "damp down" a rocket heater (as people do with combustion heaters) as a fast efficient burn is what we want. There is simply very little wasted heat. so it is counterproductive to try and burn the wood slower and longer.
A Video explaining how a Rocket mass heater functions and how they differ from a normal Combustion heater
Firewood moisture and the associated efficiency gains
Low wood moisture levels are an important (and often overlook) factor in a clean-burning fire of any type. Wood dried outside can usually only ever get as low as 15% but is more often 20%.
Here in Australia, the majority of stacked firewood I see is not under any kind of cover.
As previously mentioned, it is not usually advised (by manufacturers) to burn super dry wood but we can do so in a rocket heater. As you can see from the image below, the heat output from 30% to 20% increases by 1.7kwh. It's hard to find information on firewood dried below 20% as again, it is not advised. Perhaps it's say to say it will increase at least another kwh when taken to 10% and perhaps 2khw+ so possibly a 50% in heat output. Dropping the moisture to below 10% is impossible outside without mechanical help (e.g a kiln of some sort (which could be a crudely constructed and cheap solar wood drier) but inside a home (where relative moisture is 30%-50%) it's fairly easy to get your firewood down to 5-10%.
The issue with doing so is the space required to store a seasons supply of wood inside for your combustion heater, is going to be difficult. Not so much when your rocket heater uses 90% less wood than a combustion heater.
The Ikea Kallax shelving in the picture below is currently getting filled with 1 year dried wood (dried outside undercover) where it will dry for another 6-7 months before use.
The shelving will hold approximately 1m3 of wood.
What we can do for you
We Can build various styles of heater such as a J tube or a batch burn heater either inside or outside. We can build a heater into a hot tub or an outdoor kitchen stove.
We can also just provide a heater core for you to build your own creation around. We can provide plans along with the core for building your own. If you just want to purchase plans and go on your own, I can highly recommend heading over to www.walkerstoves.com.
We are happy to build anything from Walker stoves, so if you see something you like, please let us know
6" Walker Stoves Super Hot J Core (including a set of plans)
Flat packed $500
The 6" Walker Stoves Super Hot J Core is intended to be be used either as the firebox for a Rocket Mass Heater or OUTSIDE as a rocket stove (for cooking). It's made from a lightweight super-insulated material called ceramic fibreboard. If you were to use this as an outdoor cooker, the ceramic fibreboard would require cladding to protect it as the material is very soft.
If you want to purchase this as a flat pack, we will supply you with instructions and glue.
If you purchase the core pre-assembled, we can deliver it for a fee within the greater Sydney area or you can collect it from Springwood NSW 2777
Postage is $30 for the flat pack and $60 for the core assembled (when assembled it will be in two parts (burn chamber and riser)
This is a video of me talking about a previous workshop.
You can see the core in the video. The bricks around the feed are to stop the ceramic fibre board getting damaged whilst putting wood in to burn
Walker Stoves Brick Rocket Mass Heater
The Brick Rocket Mass Heater features the ceramic fibre core (featured above). It can be built with or without a bench and holds heat for around 8-12 hours (after the fire completely goes out).
The heater comes with a set of plans.
The cost for us to build one of these is $2000 without the bench or $2600 including the bench
Walker Stoves Batch Rocket Mass Heater
The Batch Rocket Mass heater is similar in size and heat output to the brick J-tube design (above) but the heater has a small glass door where the wood can be loaded and the fire viewed in a more traditional manner.
A freestanding batch rocket would cost $3500 and $4100 with a bench.
We can run Rocket Heater builds as a workshop on your property for you to recoupe some of the costs.
Having workshop participants helping with builds is a great way to learn but it can sometimes slow the work down. On the other hand, it could also be helpful. It really depends on the crew.
How long does it take?
We include 3-4 days of onsite labour (depending on the style of heater you choose) so if this time frame runs over (due to workshop participants) we would charge by the day to rectify any issues with the heater before leaving it in your care. We can help promote the workshop on our facebook page/website.
How much should you charge your attendees?
A good guide price to charge people to come to a 2.5-day workshop (Starting Friday night and running all day Saturday/Sunday) is between $100-$150 (excluding accommodation and food) although it is up to you. We can only accept 7 people maximum.
If you would like to check out our YouTube channel with a few videos from our recent build,
please click here.
If you are ready to get started or would like more information then please get in touch using the form below.
Get in touch
All prices are exclusive of any prep work on the site (eg slab reinforcements/piers etc), chimney installation, embellishment (e.g rendering), travel/accommodation or approvals/engineering certificates etc.