A second drum? I see the concept. This way, the inside one doesn't have to be painted too. I have a few drums that I was going to take down to scrap yard. May experiment with them.
Anyway. First things first.
I had a really strong draw. It is still windy, which helped. Though I have to removed the spinner itself, I took its cap off so I don't know if rotating blades made any difference, because gases were free to go straight up (blades are on the outside; centre has only a cross that holds them in place). When came back in, I thought that this had improved draft, but it is normally loud and think I have this impression every time I enter the house.
Throughout the burn, I also kept cooling the bell, as advised. At first, I thought it improved draw but I'm so eager to solve this enigma that my hopes can deceive me. In any case, while cooling the drum, first with wet cloth and then spraying water, I realised that the bottom MIGHT (I do not have a digital thermometer and a fluid one that I am using will not give me realiable readings) have been warmer than the top... Should that be the case (and I figured it by the amount of steam and how fast it was produced), it may have something to do with the shape of this drum. Top of the inverted thing is corrugated (only gentle corrugations but still), while the bottom is plain. Since corrugation may decipate heat faster, the impression I had may be correct.
To keep this post as short as possible, at no time did heater show any signs of smoke trying to climb the wrong way out. Moreover, I did not see smoke (or steam) at the back of feed tube (flames there were sort of lazy, but pointed towards burn chamber and no smoke or steam were swirling there).
It pulled correct and strong even when only embers were left (at that point chimney's temp was as high as bell's, which is correct but would not be the case over previous firings).
Interesting and surprising was that the bell itself stayed quite 'cool'. I am sure it was due to strong draft. In turn, there was no need for cooling it, there were no indications of heat trapped in there and paint too did not give off almost any of the annoying smell (I actually forgot all about it, because it wasn't noticable).
Yesterday I sealed the thermal crack in manifold that I mentioned earlier. Because it only appeared during heating, I had to do it with hot manifold which dried mortar too fast and it is very brittle. The idea was to fill up the crack so it will not be closing and opening again. Not sure if my logic was correct. I read that epoxy resin should be used but one I have are for plastics and wood. Not sure it those could be used with concrete.
To test for leaks, I will have to remove spinner so didn't do it at the end. But just wondering if there would be need for that.
All in all, would the symptoms I have described in this thread be caused by cold bench and cold firing? Poor draw, chinmey cold while bell too hot, smoke back and stalling after 45-60min - all of these can be caused by poor draft, right? And a warm bench should improve it, especially in my design with so many turns in relatively short run. It isn't rhetorical question
I would very much love if some one could confirm or deny.
I will keep firing, observing, changing, adding small things to see what they cause. There will be no wind on Sat and will be easiest to test for leaks
For the sake of learning, how far above roof can chimneys go safely? The insulated 250mm pipe I have used are only fixed to outside wall with stainless bands. Then every piece in the stack connects to another with a 'quick release' band
My question is: how far up can this stack go safely without the need for extra bracing?
Mine runs along the highest point and so it may not be straightforwad to add support.
I asked this in the shop where we bought tubes but poeple there were clueless
only showed us what to use to fix them to walls