Latest workshop heater

Gary B..

I agree with what you are saying on the larger batch box with the answer I gave above. I think the cast riser is helping alot and makes up for the smaller firebox. I would hazard a guess that with a ssteel riser instead of the casting things would be different, I think I would need to give the stove more air in order to keep the riser hot as the steel cools down so much faster than the casting. The stove is still giving off plenty heat from the casting 6 hours and more after the fire has gone out showing the heat that it must be storing. I know you pay for this bringing it up to temp when you first light the stove but the payback is 12 fold.

The key to a longer burn is getting this air hot before it hits the fuel, I have some new ideas on this since living with this stove and riser and I think I will be able to get the air very hot much faster and easier. Its great the way trying something new (to me) like a cast riser opens new avenues into greater efficiency. If I had a shop twice the size of mine I would only increase the size of the firebox slightly and then probably only in height a few inch and width the same, i would probably route the flue more inside to spread the heat.
Consider this heater is the equivalent of a 12 foot x 7 foot radiator putting out 200-250 C of heat for 3-4 hours on roughly one 9 inch x 14 inch log. One way of looking at it.

ppotty could you possibly do an experiment with your secondary air tube before you seal it up is there anyway that you could superheat that secondary air pipe before it enters the riser like you do with your incoming primary air

i am somewhat curious to see if it will push up temperatures even higher than what they are now thats if you have recorded them

i suspect if you do you will find that your temperatures are much higher than whats recorded already but it would be nice to know if it makes any difference to cold air entering the system

Gadily the way I have routed the copper sec air feed into the riser means it is being super heated inside the bottom of the exchanger, I will put the temp gun on the outside end of it tomorrow and find out what its getting to, I cant touch the outside end that pokes out of the exchanger which gives you some idea of the internal air temp moving through it. I made it in copper for that reason so it would suck in the heat.

ppotty query have you done a temperature reading of the new stove since you built it and have run it in now

i am curious to know what is the difference between hard run and normal run of the stove since it was made up

as i also would like to see this stoves temperatures

Gadily, I have checked the temps a couple of times but I honestly cant run it at full burn for too long as im in danger of setting fire to the side of the bench, I got it to 300c + but thats the temp of just about the whole exchanger whose surface area is huge compared to the old propane bottle, so once at that temp the workshop is getting far too hot for some of the flammable things I have inside. Its been up to 33c
I would have to open the door to burn it wide open so there is no point. It also burns just as hot with less air and gassing, I have marked the main air intake slider now with settings that get the best from the burn stage, the lowest give the fuel just enough to gas but really prolongs the fuel temps around 150c the next it gasses really hot without wasting the fuel around 300c and the difference between them is hardly anything,
It is uncomfortable to stand within 3 feet of it when burning like this. The lower gassing temp with just one or two small logs runs between 150c-200c and keeps the shop around 25c for 2-3 hours per load, full firebox 200c-250c 3-5 hours depending on timber. you get peaks and troughs in the temp output during the gassing burn cycle but the shop temp remains fairly static from 20c-25c all day. Temps the next morning will be around 15c around 12 hours after the burn stops.
Fuel used per 10 hours is 3 firebox full again depending on the timber. less fuel on very dry hardwood.
In summary once the stove is hot enough to gas about 20 mins I refuel and shut it down, few hours later I just add a couple of logs with a little more air to heat up the firebox then 5 mins later back to lower air setting, only need to do this 3 or 4 times a day so its no problem. Most days I let the fire go out after 3 burns as its warm enough not to need any more heat for the rest of the day. The bricks on my flue have stored enough heat to do the job.

I took the top off the exchanger at weekend to inspect the riser, it is just as I fitted it no damage or cracks and as clean inside as the day i fitted it, was surprised at just how clean it was no signs of soot or that anything had been burned inside! There was a very fine dusting of talc like ash in the bottom of the exchanger but other than that you wouldnt think it had even been used. There is slight black coating to the inner walls of the exchanger which you would expect. Very pleased with it and about the only thing i will be doing is adding a flue damper to retain the heat once the fire goes out.

id like to ask another question here ppotty on your build the top plate was the whole top plate at the same temp all the way across it the full top plate including its corners

as i m just about to start my new design on the rocket burner as just got all the materials to do it last friday as im considering adding in a water system into it

Thanks, you kind of blew the standard idea that a batch has to be certain dimensions out of the water.

caotropheus wrote:

Mr. ppotty1,

Your description is very impressive for the amounts of heat the stove produces. The beautify bit  for me is that the stove is naturally aspirated, not forced air. Two things, unlike an engine, there are more and more home made experiments that seem to show that there are some advantages to bring pre-heated air to the primary combustion of the rocket stove. And it seems that the hotter this air gets to the primary combustion, the better. Just take a look at your stove and at Barnabe's stove. Second, I suggest we organise ourselves, improve even more the stove and manage to get a way to send you + the stove to this competition

I'll say it because I don't shut up and get myself into trouble for speaking my mind so wtf.  If you are a Paul Wheaton pet, then yes, you will get to the contests and special events, otherwise the chances are slim.  

I would love to see someone outside of that permie group make it.  It blows my mind when they stumble onto an idea that has been floating around the metal stove rocket community for years and think it is an epic discovery.

Good stuff Loz, I have been missing out on this thread.
Just found it.

Hitchiker the pemies lot are still flogging the same videos they made years ago when you look nothing has changed since they were wearing flared jeans lol.
As someone showed me they have renamed a vortex a "shirly temple" because obviously their rising star van der berg was the first to think about it and implement it....yea right!
all their work is targeted at selling videos and selling courses when you look but its all basic stuff you can find on you tube for free.

That is what gave me a chuckle but I do not fault them for taking advantage of selling dvds.
Really if you think about it, the ones buying it either have no clue its all free on the net or they would rather have someone compile the information for them to buy which is cool.

Pp,

Hows this stove doing?

any updates?

keepittoasty wrote:

Pp,

Hows this stove doing?

any updates?

Its still running great everything working well and as it should. only minor problems are the seal between the firebox and exchanger has a slight gap again, but thats down to the heat and movement....come summer I will do a proper fix on that to stop it happening.
Only other minor is when the stoves not been lit for a week and it the air outside is still and damp the stove is really sluggish to get going as in it wants to burn up the firebox and not into the riser. I put this down to the cast riser being very cold and probably damp from drawing the air in through natural convection. It just needs a few sticks pushed into the riser base and after a few mins its heated up and drawing well. The answer to the cold riser is to close off the air intake when im not using the stove, but having a memory like a sieve forget that.

I saw this today.



its all in German, but around the 15 minute mark he goes on to show Pp's vortex design. nice stove. He isnt using insulation around the firebox, but in his YT comments he remarked he will in the next build.

Interesting to me was he is using preheated secondary air, but it was fed from the firebox, as in no connection or feed from outside the stove. the intake end of the secondary pipe, however is near the top edge of the firebox where pre heated primary air comes in. you can see the tube at the 8 minute mark, I did not see any secondary air controls being used, but I cant speak German and could have missed it.

noticed the same failed design with secondary air would have been better to have it external therefore slowing down the primary air inside the box

Yes the sec air wont work with the feed inside the firebox as that pipe gets hot the air wont move down it with the open end inside, he would have been better taking it straight out of the front so he can run it independently from the primary as Gadily said.

That's right, I remember you making your copper secondary pipe sloping up for that reason.

Awesome info guys!

Ppotty1 thank you for You Tube channel, I have learned allot from your videos. I like the modular design of the latest stove.

Potty1,

Now that you have used the cast riser through the winter are you still satisfied with casting mixture? You used quite a lot of pearlite versus refractory mix and I am wondering if it held up.

Also the area of the riser (35.7 sq. in) is larger than the opening of 30 sq. in. and even smaller with the vortex "kick out". Was that pre-planned to create a restriction to get draw?

I am just now beginning the design of my cast riser stove and want to make sure that if I copy your design, that it is tweaked to what you think is now optimum.

NHtrout

NHtrout wrote:

Potty1,

Now that you have used the cast riser through the winter are you still satisfied with casting mixture?  You used quite a lot of pearlite versus refractory mix and I am wondering if it held up.  

Also the area of the riser (35.7 sq. in) is larger than the opening of 30 sq. in. and even smaller with the vortex "kick out". Was that pre-planned to create a restriction to get draw?  

I am just now beginning the design of my cast riser stove and want to make sure that if I copy your design, that it is tweaked to what you think is now optimum.

NHtrout

Yes the casting still shows no sign of any failure the last time I looked, I have not been using it since spring arrived and Im going to be doing some work on the stove before winter comes around again so will post up a new vid with the slight changes and the firebox refractory castings.

Yes wanted the restriction in the riser feed to create that draw of gasses which really pulls once the riser gets hot, its better to restrict that area than to overload the riser and have a weak draw on the firebox if that makes sense.

ppotty1 Admin wrote:

Yes wanted the restriction in the riser feed to create that draw of gasses which really pulls once the riser gets hot, its better to restrict that area than to overload the riser and have a weak draw on the firebox if that makes sense.

the restriction has an effect of making the air move faster into the vortex part of the system therefore has a much better draw or pull from the fire burning within the system

if you need to check the info look up air conditioning also has the same effect when you reduce down from 22mm too 15mm

PPotty1,

Thank you for posting the update to the stove. Fantastic! The cast riser is indeed far superior to metal in terms of longevity and efficient operation.

I am building my stove to fit into an outside enclosure as I do not have anywhere in my house to put the stove. The entire structure will be made from metal and heavily insulated, much like a small outhouse (WC) to you. The top will duct into the house and use a fan to convey the hot air horizontally. This is on the drawing board just now but will begin to take shape in December.

Best,

Randy

Hi Randy...consider covering the inside of the walls with a brick or block layer you could just stack them dry against the walls with the insulation behind them. These would probably give you 3-4 hours of heat once the fire goes out.
Ive thought about you drawing the air into the house with a fan and the same air drawn out must go in to the outhouse to replace it. Two options here either vent this back in from the house via ducting near the floor or bring the air into the outhouse behind the bricks.
Leave an inch gap behind the bricks and some slight spaces between the bricks as you lay them. The bricks will warm the incoming air.
I would also vent in the stoves air supply via ducting as I did on this stove.

PPotty1,

Great idea on the bricks. I'd not have thought of that and it makes perfect sense to do this as a heat reservoir.

Thanks loads!!

Randy

PPotty1,

Have you weighed the cast riser? If so what is the weight and if not what is your best estimate of the weight?