Note this is long post with a sound track and pictures – you have been warned… After a long time and many, many hours of work, our big boiler (BB) is back online. It’s actually been up and running for a few weeks now and I have been able to get some of this down for posterity.

Back in April of ’11 the cast iron steps in BB collapsed. We limped out the rest of the spring just with our little boiler. I spent quite a few spare moments over the summer pondering what to do next and how to go about it. Something new was out of the question we just couldn’t afford it. After quite a bit of reading and research I decided to perform a fairly radical retrofit. I settled on trying to model the refit after a commercial wood fired boiler made by a company in Worcester called BCS. Luckily the Cavicchio’s happen to have a couple of these in use over in Sudbury. Both Paul and Jake were super-helpful in letting me ask 1000 questions and crawl all around in their boilers.

The whole project didn’t get started until September. I knew going in it was going to take some time. I broke the work into 2 major phases, the first being a major plumbing change to be more efficient in how the hot water is used and circulated. The second phase being the actual refit of BB. I was optimistic that the phase 1 changes would buy me the time I would need to finish phase 2 while only running with the little boiler (LB).

Then we started to attack the plumbing. All of our major pipes in the boiler room are 4″ steel. These beasts are welded. We were able to cut, fit and re-plumb to alter the water flow. The problem was once we put the water back in we had a nice rain shower going on. I’ll take copper pipe and solder any day after that. We eventually got some outside welding help and dried things out. The changes worked great and ended up allowing us to run the little boiler down into temperatures in the mid-20′s. In the past we were lucky to run into the low 30′s with only the LB. As it turned out later this was a huge boon as the second phase was rather ambitious.

Phase 2 involved cutting off half of the firebox from BB, rebuilding the refractory wall, installing a new elevated floor with special airflow capable firebrick and installing a new horizontal chip feed mechanism. The first part was the easiest, of course. Take a cutting torch go wild. I think I am going to amend the old saying, if you can’t fix it with a hammer and duct tape it’s not worth owning now that I have a cutting torch. We yanked the old parts out with the CAT. Rebuilding it took somewhat longer. By way of Jake I was very fortunate to hook up with Walter Lane. Walter’s a great guy who knows alot about boilers. He and his brother drove out from Troy and sold me a bunch of awesome leftovers from other projects. He also had a few great tips and ideas on how to greatly simplify what I was going to do. He saved me hours and a good deal of money I am sure.

We ended up finishing the basic work somewhere in early December. We then got into a boiler tube replacement dance, where the fire tubes leak, you yank them out, put in new ones, and in the process open up leaks in a few more tubes. Rinse, lather repeat and it’s almost Christmas. We finally started getting a fire going sometime in late December. Of course we had a few issues to iron out. The main one was the new chip feed jammed all the time. I was worried when we put it in that we had undersized one of the tubes. That proved to be the problem, so we cut it off and put in a much larger tube. Since then we added some fine tuning and a off delay timer to help smooth out the feed. We have been running it nice and hot when we need it, it burns less chips, hardly generates any slag and can be too much fire if it gets too warm outside. The next tuning/tweak we are now doing is to alter the drive gearing to slow the chip feeds down even more. There are times when we run too hot and by the time the heat has been pulled off and pushed into the greenhouse the fire has gone out.

The following gallery is a series of pictures I gathered over the last few months as we hammered this out (literally). I now have time to write this, and even work on other things.