Dragon Burner - Precast Rocket Heater Cores - Now Shipping

We are please to announce that we are now shipping pre-cast rocket heater cores. They come in 3 sizes and can be shipped via UPS. These cores will tend to run much hotter than a normal rocket heater, so you may consider downsizing. They were designed by Peter Van den Burg and are the state of the art. Attached is the family portrait.

More info can be found at
http://www.dragonheaters.com/dragon-burners-rocket-heater-cores/

cheers

Very nice looking!!!

Glad to finally see someone offering these prefabricated shipped at a decent cost!

Keep up the good work!

those look great! definetely makes the process of building the entire system much easier

I'm interested in the 6" Heater and would like to know more about the box option. As I didn't see a contact on the Dragon Fire site I turn to you-how is box worth the extra $$. Isn't it a customizedi steel thermal painted box?

Well done!
Prices?

Although out of my price range, I have to admit this is SWEET! I hope you are very, very, successful.

Could the 4" be used with a gas style water heater, to force the exhaust down through the water heater's vent tube and then out of the house from the bottom? Specificly, could I put a 4" core and barrel on the main floor, and then force the exhaust down into the basement and through the water heater before exit?

Looks great. I like the secondary air supply.

What is the approximate heat rate (btu/hour, or lbs of wood per hour) for each model?

The price differential between the complete unit that Zaug offers and the Dragon Heater barrelless box unit or the two of those versus the Drago Heater cores is significant. However the Dragon Heater website has no contact info so I can't ask such basic questions as which (used?) barrels work best, which to avoid, is the barrel welded to the box and when will a photo of the box be on the site. Probably directions would come with the the core or box however I'm not ready to commit my funds without feedback. Answers to either the technical or the contact issue eagerly awaited!

My apologies on the website, the phone number is now posted as well as a contact us form. We will have some new photos and plans on using the cores up in the next few weeks.
Thanks

And you did a thorough job of answering questions once contacted-thanks. Hope your website builder has been properly harangued as it was most frustrating to not be able to tell a company that you can't tell them...

Marcos Buenijo wrote:Looks great. I like the secondary air supply.
...

I agree they look good... but I don't see where they've been tested with a full installation.

The secondary air supply sounds good on paper (it's a clean-burn feature in woodstove design, to counteract the operator's tendency to close down the primary air feed).
It also works OK in outdoor mockups when working with the J-tube or combustion chamber alone.

But with the load of a full thermal mass system, our experience has been that any secondary air downstream of the feed tends to produce a 'leaky siphon' effect where the downdraft through the wood is diminished. I have seen a few folks (notably Matt Walker) who've made a secondary air feed work by diminishing the size of the primary feed, and/or by super-cautious handling during the burn. Would love to hear more about how this is working in actual installations.
Possibly you have compensated with some other feature to boost draft and overcome this effect? Or you're pulling air from within the feed, and re-feeding it, so the opening itself has no change in draft?
When we boosted draft, it tended to make the burn dirtier... your model may be balancing these requirements differently somehow.

We're not going to advocate these until we've had a chance to play with one in person, but I'm excited to see that they're out there. Would love to hear reports from beta testers on performance with full thermal mass in actual buildings.

-Erica

any feedback on this design?

found some references to it several years old, but little feedback on whether the design has been superseded, or is this the "state of the art"?

Is this the same design, or someone else's work?

www.scribd.com/document/342025997/Dragon-Heaters-vs-Rocket-Heaters-pdf

greenlifehomestead.com/8-rocket-heater-core/

I am building a maple sap evaporator based around an 8" L-tube core.  Low thermal mass/no heat storage so the concerns about secondary air intake stalling the draft don't apply in my application

I can't tell where the secondary air is coming in - is that a separate channel in the metal feed tube?

Have the vortex-inducing wedges been tried and tested?  They would be fairly easy to implement in my core.

Hi Tyler;
As you see this is an old thread.
However, the link to greenlife is currently up and running.
I suspect that they bought out the rites from Sandy.
I have only heard good things about Sandy's stoves, I know she bought the rites from Peter for his J-Tube "hot rod" modifications.
Batchboxes were just coming on the scene when "dragon stoves" were released
On the greenlife site I was surprised by the dimensions given and the claims made on performance.
I was shocked at how much they are asking for what you received, but I guess it is 2025 and things cost more than I think they should.

yes, the price is a bit silly, but I'm planning on building one, not buying it.

I heard back from greenlife about my query.

They are stating 75k BTU/hr max output for the 8" J-tube.  That is not going to be enough to meet my application need for 100k BTU/hr, so I am going to need to inject some form of forced secondary air to accelerate the burn rate.

Perhaps, you should look into batchboxes, they have surpassed the J-Tube design for heat output and duration of burn.
Combined with a stratification chamber, they are quite amazing.

I found this (old) post from Peter estimate 18 kW (61 kBTU/hr) for a 6" batch box; that's not going to be enough for my application.  

https://permies.com/t/59252/Estimated-calculated-heating-power-batch

In my case, the heavy stationary design of the batch box is undesirable; I need to roll it away after use.

I understand those off-grid are loathe to add forced air intake, but in my case it's cheap to buy a blower and easy to connect to an extension cord.  And it will really crank up the BTU output rate compared to natural draft (either J-tube or batch box)

Yes, forced air will be just like a kiln
Your wood consumption will be higher and you may find yourself overfueling and getting black smoke from your chimney.
But I would imagine in a sugar shack that is not a concern.
Let us know what you build, hopefully with pictures.

yes the blower will have to be variable speed so I can adjust the burn rate

I plan to have K-type thermocouples at the top of the firebox/riser, and at the exhaust outlet to help me understand what fuel-air ratio gives me a reasonably clean burn at the max output rate