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Is a 2" riser a ridiculous idea - given that I want a really low output?  RSS feed

 
Posts: 2
Location: Ystad, Sweden
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Hi all.

I'm looking at different ways of warming the workshop/garage, and want to create something that warms with a low output, but burns for a long time. I don't have room for a thermal mass, or a large burner, and I'd ideally be able to fill a hopper with wood pellets (we use pellets to heat the house) and leave it to run for a couple of days.

I'm in the dairy industry - So I have a nearly endless supply of seamless stainless piping - the question is, would I be wasting my time by going so small? I've read threads where people getting a stern dressing down for using 3" risers, but they're looking for a larger output than me. All I want is 1Kw ... or a max of 2Kw.

Thanks for any input!

/Nick
 
gardener
Posts: 2713
Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
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Nick Portinson wrote:the question is, would I be wasting my time by going so small?

Yes, absolutely! Anything bellow 6 inches is a waste of time imho!

Rockets without tending don't exist. Pellets burners have been done, look for web4deb on youtuve. And be sure you check his heat riser autopsy and rebuild! Because

Metal is doomed!
 
gardener
Posts: 2581
Location: Upstate NY, zone 5
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As someone else said recently, if you want or need a long slow burn as opposed to storing heat in a mass, you don't want a rocket heater. You can't have anything that works effectively and efficiently as a rocket with a small trickle of flame. The smaller you get, the more heat you lose to the surfaces of the burn chamber compared to the usefu heat for high temperature combustion. Anything with metal lining the burn chamber will lose even more heat than a masonry construction.
 
Nick Portinson
Posts: 2
Location: Ystad, Sweden
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Thanks for the fast and to-the-point answers guys. I'll figure something else out that isn't a rocket!!

... still want to build a rocket for something though... maybe the future greenhouse needs one...

 
Satamax Antone
gardener
Posts: 2713
Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
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Nick, is your workshop well insulated?

If yes, you could do a 4 or 5 inch batchbox, and lots of storage, which would be insulated with covers, blankets or else, and trickle the heat afterwards, for long hours
 
pollinator
Posts: 4154
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
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Nick Portinson : It amases me how many people get nervous about the thermal mass bench ! Let me try to give you a possibly better way to look at a Rocket
system.

Correctly running a rocket heater is done by ear, we want to create a freakishly hot Fire ~1100ºC~ to gasify the wood fuel, at these temperatures we get a Hot
clean burn with very little particulates fly ash or pollutants , just very high efficiencies, with the highly Refractory materials we use to surround and insulate the
combustion core this happens within 5 minutes.

This threshold can be easily observed in a darkened room as the Burn Tunnel will glow a dull red, from that point on it is possible to throttle back the amount of
wood and its necessary combustion air, and still receive the benefits of a clean burn. This is totally unlike trying to load a lot of wood in a 'regular wood stove'
and then closing it down to last a long time, which results in a great loss of efficiency !

Placed in a good centralized area within your workshop, you will be able to quickly hear and observe Your Rockets needs, tending it is an automatic response
that you make to your Rockets needs with no more conscious though than you take in adjusting a pair of reading glasses!

This attention given while you work in Your garage, over a period of 3 - 6 hours will when coupled with a Thermal Mass Bench to store and re-radiate the heat
energy will give you 12- 24 hours of additional heating!

Think of the Thermal mass bench as a custom made work bench that can be just as high or low as you want it to be! A custom job built just to make your work
stations more productive, or the Thermal mass can be routed underneath existing benches, I can not speak for your work shop but my experience is that the
space under most work benches quickly fill up with stuff and never gets the cabinets you promised yourself that you would build there !

So- The Rocket Heater is Very, Very efficient at turning the Chemical Energy of your wood fuel into Heat energy, ~40%~ of the heat energy thus made is radiated
off of the surface of the barrel, it is at this point that your next decision ether condemns your Rocket to being a poor wood stove or a super efficient heater that
allows you to use 1/5th of the wood of a regular wood stove!

Are you going to vent the hot exhaust gases outdoors like a conventional wood stove, or are you going to make the next step a positive one, build a Thermal mass
bench, and capture the additional 60% of your Rocket Heaters Thermal energy !

Will you come in from a day in the fields to a cold Garage structure, or to a warm workshop !

So we have addressed size, for a 1st time build a 6'' system is very doable, and can be fed much less wood which burns freaky hot and efficiently, as compared
to a smaller unit that No-one here at Permies.com is going to recommend for a 1st time build !

We have discussed the idea that Your Rocket will constantly tell you how 'happy' it is, tending it is not unlike having a plump bank account into which you make
regular small deposits, and get Automatic withdrawals in the form of heat, pleasant, ever present, bone warming heat !

Bench location can ether be finessed to give you a new workroom, or be the single stumbling block that keeps you from heating your garage with no more than
the scraps of wood that pileup in every odd corner and hedgerow on your farm !

Our Fellow members are correct about the fate of Iron and Steel in the Rockets core, A google search can connect you to articles on 'High Temperature Hydrogen
Attack' and 'Hydrogen and Steam Embrittlement' !

As they say- "Rome was not built in a day'', if you continue to come back here to Permies.com eventually we will infect you with the Delightful madness that is
Rocketeering ! For the Good of the Craft ! Big AL

 
Posts: 39
Location: Western Montana
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It sounds like your best bet might just be to put another pellet stove out there... I have three pellet stoves to heat my house, but the garage is heated with a massless rocket stove. I actually have another pellet stove I could have installed out there, but I wanted to burn wood because I can basically get it for free. A pellet stove takes up a lot less room than a rocket stove, if space is an issue. They also have much closer installation clearances (many of them only need a few inches of clearance from a combustible wall). They can also be run off a thermostat, and don't have to be fed every half an hour like a rocket stove. Set on low burn, my big Avalon might be able to squeeze two days out of a full hopper (about 80 pounds of pellets). That's with a constant burn that never shuts off. But, since it can run on a thermostat, that may not even be necessary.
Anyway, just a thought...rocket stove isn't the answer to every heating situation, but you may definitely find one it's a good fit for .
 
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