Hello rocket stove fans! We’ve made some good progress and we’re now at a point where we have all the materials, burned the barrel, prepped the pipes, made the heatriser, built a couple of test-setups outside and fired it all up. Exciting stuff!
Some questions arise and we’d really appreciate any guidance. We are not sure how advanced our test set up should already be, or whether the things we are seeing now already mean there is no use to further make the test set like the real situation (like cobbing certain parts in/closing parts off, etc) I have attached 3 pictures showing the set up.
- First image: For reference our bricks have the following dimensions when laid flat: 230mm long (9”) x 110mm wide (4.5”) x 60mm high (2.5”). Feed tube is on the left. Burn chamber spans 5 bricks, so 300mm (12.5”). The heat-riser will be placed on the right. (We have a custom-built heat-riser. We have a 55 gallon drum (200 litres), the heat riser has been filled with a perlite clayslip mixture.)
- Second image: another view of the brick set up
- third image: test set-up with barrel over heat riser - after the fire has been burning for 4 hours without the barrel (just heat riser, to dry it out) -still burning sideways but not so enthusiastically, and we have raised the barrel with a few extra bricks to get better results.
We made a first test fire yesterday with just the bricks and un-insulated heat riser, and it burned sideways. Then we insulated the heat riser and made a test fire with just the heat riser in place, but the fire would not go sideways unless we primed it by dropping a piece of burning newspaper into the heat riser. We kept it burning sideways like that for a while, but we got a lot of smoke back. When we would lower the barrel over it the fire would stop burning sideways. We think this is because the heat riser is still completely wet (we made it in the morning and started testing after lunch) and probably cold. So we decided to keep it burning for a few hours. Now in the evening, the heat riser starts to dry out and is warm/hot along the sides. if we lower the barrel over the heat riser it continues to burn sideways, although less vigorous, and smoke back happens occasionally, although mainly when there are strong gusts of wind (it is a windy day).
A few thoughts/questions after all the enjoyable experimenting and also worrying amount of smoke back we saw...
Question 1: There was hardly any smokeback during the first test. But that was a very nice day with hardly any wind. The second test was on a windier day... Does this explain the amount of smokeback we see and would that not happen inside?
Question 2: During the first test the heatriser was without insulation. The second test was with an insulated heatriser, but it was still wet (and cold). This will probably have an effect? Can we only judge performance when the heat riser has dried out completely?
Question 3: This is a test-set up without mortar and with gaps. The barrel isn’t cobbed in yet (simply paced on some bricks). When we mortar everything in, can we expect better results?
Question 4: we have not even connected the pipes yet... do we also first need to do that as well or do we first need to make sure we get better results without the pipes?
So, we don’t see perfect results, but the setup is only a test-setup... Not sure what to expect? Should we tweak things until we get better test-results before we start doing the real build or is this all a perfectly normal part of the process? Do we need to build a more advanced prototype before we can judge things?
We’ve double checked all the dimensions against the information in the book and those look fine... Without the barrel we hear a nice rockety sound, which apparently is a good sign...
Any feedback/encouragement would be very welcome at this stage
Thank you in advance!!