Recover heat from wood stove

In this project I’m making a water boiler so I can recover heat that’s going out the chimney.
The parts used for making the water boiler:

-          1 tube 120mm diameter – 500 mm length – 2 mm thickness .
-          1 tube 250mm diameter  – 400 mm length – 2 mm thickness.
-          1 tube 50mm diameter – 170mm length – 4 mm thickness.
-          2 pieces of sheet metal for the lids – 3 mm thickness.
-          3 connectors threaded at one end – 3 mm thickness.
-          1 pipe coupler used for connecting the thermostat.
The tubes that I’ve bought for this project had 1000 mm in length so I had to cut them at the proper dimensions, for this I’ve used a trick: marking the length that I need on the tube and connecting the points using electrical tape (any tape will work) so I can see better the cut line.
After cutting the tubes the next step was to drill the holes needed.  In the smaller tube I’ve drilled two holes at an angle so I can fit trough the 50mm tube.
In the larger tube, 250mm one, I had to drill three holes: two at the top and one at the bottom. The holes at the top will be the ports for: hot water out and thermostat, the hole at the bottom will be for water return in the boiler.
Cutting the lids for the boiler was the biggest challenge of this project because I used a metal cutting blade in my jigsaw and a metal file to make adjustments for the inner circles. For the outside circles I could use my angle grinder to make adjustments.
The dimensions that I’ve used are not random , I’ve calculated the volume of water inside the boiler to be a bit more than 15 liters.
After preparing all the parts the next step was to weld them together and for this process I’ve used my mig welding machine.
The final step before installation was pressure testing the boiler for leaks and I can say that I was released to see that I didn’t had any leaks.
Installing the water boiler was challenging because I had to do all the plumbing work but  the end result worth it.
Bellow you can see the block diagram of the installation that I’ve made.

Thanks for reading.