Hello! I'm designing a batch box to heat an house of about 102 m2 1097 sf. The building has already the radiators system so I want to use this stove to heat primarily the water. I opted for a 8" system, do you think will it be sufficient? To heat the water I decided to put a big boiler next to the heat riser that will feed directly the water to the radiators. Also it will provide hot sanitary water by using a copper serpentine. The boiler is opened at the top. I also added a white oven directly on top of the burn box and a little cookplate over it but I'm not sure if it will reach enough high temperatures in that position. What do you think? Note, the bell that include the boiler and the oven is made entirely of insulating panels (in white)
This is how this thing should looks like. There is an existing fireplace on the right so I had to work out with some space restraints. Being the firebox lifted up from the floor the whole stove turns out to be raised and it almost reaches the ceiling but I think it's worth it for the comfort of putting the wood without bending.
This how the heating water system should work: Hot gases come out from the riser and enter the bell that contains the water boiler. The boiler itself is placed on the top of the bell in order to transfer most of the heat generated to the water contained therein.
There are 2 tubes leaving the boiler directly connected to the radiators system; by means of a pump the hot water contained in the boiler is sent to the radiators while the cold water returns from the radiators to the boiler. The water contained in the boiler is the same as the one contained in the radiators circuit. This is an open vented system and the boiler is opened at the top with a tube to vent out the steam.
There is also a serpentine inside the boiler to generate hot sanitary water whose tubes are directed to the attic.
The primary bell is entirely made of insulating panels so that only the boiler will absorb heat, followed by the cooking plate and the oven. The total heat absorption area is about 1,5 m2 (16,14 ft2),
the bell CSA is 0,47 m2 (5,05 ft2), minimum should be 0,24 m2 (2,58 ft2).
The oven's floor coincides with the firebox ceiling so it should became quite hot especially towards the end of the burn. It will extract some heat from the firebox which it's not so good but I'm just trying to find a compromise.
The hot gases that flows in the first bell should get in contact with the top and the sides of the oven. There is a little hole (15cm x 15cm) in the bell located over the top of the oven that leads to the cooking plate, shedding heat externally. But I have some doubts that it could became hot enough to make some cups of tea.
The detail of the bell extension that should make the oven and the cooking plate hot
The second bell is a bench. The gases will exit via the vertical flue that you can see in the picture. I need to find a way to lower the exit point to allow only the colder gases to leave the bench. The problem is that the condensate cap under the flue is taking much space. The orange cylinder is the water circulator (naturally outside of the smoke path)
This bell ISA is 3,9 m2 (419,7 ft2), adding the first bell ISA of 1,58 m2 we get a total of 5,48 m2 (59 ft2). I read that a 8" system should have an ISA of 9,4 m2. Do you think is it worth it to add some "columns" inside the bench to increase the surface area?
Last Edit: May 15, 2017 12:18:15 GMT -8 by bulbius
Have you counted how many kWh (or MJ) the water volume in the system may absorb?
I can see the tank is 800x400, right? will it be made of acid-proof stainless steel?
Make sure the water used is not "soft" so as it didn't fur up with (CaCO3, MgCo3 ). (We used harvested rain water to fill up a buffer tank)
Project a clean out flap allowing to reach the space under the water tank. My nose smells a flyash precipitation in there
I also can not see a shortcut (bypass) to the chimney (to allow smokeless start up of the "cold" system )
Unfortunately I'm not so familiar with formulas and calculations, I'm used to doing this way , so I just based my choices on my previous work where I used a similar boiler and on the space available inside the bell. I could use a smaller boiler inside the bell and put a very big water accumulator tank in the attic exploiting the natural circulation but if there is a possibility to make things simpler I like to catch it and what remains is only a boiler connected with radiators. Simple as that.
In the sketch the tank is 800x400 right but it's indicative, it all depends on what I will find. In my previous project I used an old electric water boiler after removing the insulation, this wasn't stainless steel but inside was lacquered. It's almost 3 mm thick so I think it should last long. The last time I saw it looked like this:
It was covered with a thin layer of soot (that certainly will reduce the heat transfer but it's inevitable) but no sign of corrosion. Under it you can see the pedestal with the condensate collector. During cold starts it can produce more than 1 liter (0,26 gal) of condensate!
The water I'll use to fill the tank will come from a wellspring while the one I used in the other project come from a well. I will project an inspection point under the boiler and under the chimney. Also both condensate collectors are not shown in the sketch.
Regarding the smoke bypass I would not put it, it is another element that can add complexity to the design and durability, I really hope in a happy cold start without it.
Hello guys! I want to update you on the outcome of this project. I'm quite satisfied, the stove has been running for two months to date without problems. The space to be heated is large so when it's very cold outside we need to load the stove 3-4 times in a day. The white oven works nicely, after the embers phase it can even reach the full scale at 300° C.
This is the final result: I made the painting with clay and glue flour. The top of the bench is made of concrete slabs but after some time they become too hot so I need to cover them with something.
This is the construction of the heat riser and firebox. The whole is insulated with aircrete blocks
Octagonal riser made of 3 cm thick firebricks sealed together with refractory mortar.
Here you can see the firebox with the port and the floor p-channel housing
To support the bricks that form the top of the firebox (that is also the base of the oven) I used l-shaped iron rods.
The door with a thermal glass stolen from an old electric oven.
The first layer of plaster made of cob.
Insulation of the heat riser with 2.5 cm thick ceramic wool
I wrapped the ceramic wool with a stainless steel sheet and I poured expanded clay between the two.
The 100 liters boiler made from an old tank with the two pipes connected to the hydronic system and the vertical pipe that handle the overflow sending it to the condensation discharge. The boiler rests on a kind of cup that collects its condensation.
The stainless steel flue that drain its condensation on the discharge located on the floor. You can see also the boiler overflow pipe.
The copper serpentine that heats the sanitary water and the float valve that replenish the water of the boiler.
the top of the bell where the heat is maximum is made with stainless steel sheets surrounded with ceramic wool and aircrete blocks. The main goal of this stove was to heat the water inside the boiler so I insulated as much as I could the other areas.
I didn't put a bypass so during a cold start it's necessary to light the fire slowly to heat the water contained in the boiler without producing too much condensation. Otherwise if you burn a full load during a cold start the smoke (mostly water vapour I guess) will escape everywhere. During the winter the stove never gets cold so there are no problems. I think this is due to the unconventional design (with boiler inside the bell) that make this stove different from what has been tested. Apart from that I'm satisfied with the build, the stove has a very good draw even when I totally open the door, the air intake is very comfortable and it can be adjusted easily in every burn phase. Soon I'll post some videos.
martinm: any one here with info \ experience with heat (from a mass heater) distribution with ducts throughout two storey house ?
Sept 8, 2018 22:58:52 GMT -8
padica: Good morning, this is a wonderful subject, please someone can help me with the theme of double and triple combustion, how it is achieved, theory and design, thank you
Sept 15, 2018 7:13:40 GMT -8
wiscojames: I'm afraid you won't get a response to such a vague question - I suggest reading through some of the threads related to your questions before asking for an explanation. People will be very generous with their knowledge if your question is more specific.
Sept 18, 2018 4:48:00 GMT -8
daniel: in my experience as I am working now on something of that nature, I have thought of making a heat exchanger and distributing the heat through vents using a slower fan. Now after a few years I realize that mass heaters give out primarily radiant heat, for
Nov 30, 2018 12:48:38 GMT -8
coastalrocketeer: Anyone posting in this shout box... if you have something you want people to see and respond to, create a thread in the appropriate forum section... this is not the place...
Dec 16, 2018 18:10:49 GMT -8
vesuvius: High Temperature Glass options,
Jan 4, 2019 16:28:17 GMT -8
vesuvius: Do any of you have experience with using the glass from home oven doors on a rocket stove? I'd like to have a viewing port on my stove but don't want to fork out for new ceramic glass. Any thought as to whether it would take the heat of a rocket stove?
Jan 4, 2019 16:30:40 GMT -8
yaya: you dont need the blowair for that temp..
Jan 13, 2019 16:43:57 GMT -8
flybywire: Glass window from an old washing machine is designed to take high temps. Cheap solution to your need.
Jan 27, 2019 0:10:58 GMT -8
coastalrocketeer: Anyone posting in this shout box... if you have something you want people to see and respond to, create a thread in the appropriate forum section... this is not the place to have a discussion... it is for short announcements
Feb 7, 2019 0:11:23 GMT -8
coastalrocketeer: you won’t likely get replies to questions here, and it is not a spot that makes holding an ongoing discussion possible...
Feb 7, 2019 0:12:22 GMT -8
TexasGonzo: Sooooo glad I found this site! Its always rewarding to find such a super group of folks! To any and all, feel free to PM me anytime. Thanks for having me!
Mar 11, 2019 18:56:41 GMT -8
jlmtech: GADGET: CONSIDER USING A JET PUMP INSTEAD OF A BLOWER FAN TO INDUCE DRAFT; NO CLOGGING.
Mar 26, 2019 8:19:28 GMT -8
michaelegan: i am unable to open the sketchup files on my mac. I used sketchup a few years back but apparently the company now requires a subscription. does anyone have any advice/instructions on how to use the program or how to view pictures without spending money?
Aug 20, 2019 18:41:48 GMT -8
mannytheseacow: michaelegan: download AutoCAD student version for free... import .SKP
Aug 23, 2019 13:33:44 GMT -8
topbaza: hi everyone, been searching all over net and this is were i need to be i think!!
Sept 28, 2019 6:16:25 GMT -8
anounaki: Hi, why I cant upload photos when I make new tread to this forum?
Feb 28, 2020 2:09:40 GMT -8
ahansen: photos under 1 mb not possible?
Jun 4, 2020 0:09:21 GMT -8