It is a major task!
The longer version of the story is that the process was actually very enjoyable.
It requires the smokebox, which will eventually support the front of the boiler to be removed. This is to allow access to the front of the boiler for fitting the superheater, the blower pipe and a thing called a snifting valve pipe.
You can see here the boiler supported by some packing to keep the front at the same height as it will be when supported by the smokebox. You can also see the blow down valve poking through the frames at the back.
The first task is to fit the superheater. As I have been collecting my kits, rather than having Polly send them out, I have a free upgrade to a steel tipped superheater. I should have taken a photo of it before I fitted it! This runs the full length of the large flue in the boiler all the way back to the firebox and is more efficient than the shorter copper version.
The superheater attaches to the wet header of the boiler via a banjo fitting. To aid sealing of the joint the two copper washers are coated with jointing compound.
The banjo fitting is done up finger tight and then the union nut on the other end of the superheater is aligned with the steam inlet pipe as shown below. Once everything is aligned the nuts can be tightened further.
Once this was all located it was time to move on to fitting two further tubes.
The first is the snifting valve pipe. I had to look up what a snifting valve was. Wikipedia to the rescue https://en.m.wikipedia.org/wiki/Snifting_valve
In essence it allows air into the system when the loco is coasting with the regulator closed so that a vacuum doesn’t build up in the cylinders.
Matt at Polly warned me that getting this well aligned before fitting the smokebox was vital as fiddling around inside the smokebox once it is fitted to the front of the boiler is a bit of a pain.
The final pipe on the front of the boiler is the blower pipe. The blower helps draw the fire when the loco is stationary or when raising steam. To ensure that it works effectively it needs to point up the chimney parallel to the blast pipe with the tip just above the blast pipe.
So that completed the initial fit of the boiler. I now have to wait until the jointing compound has gone off before moving on to the final fit of the boiler with the smokebox.