Hi! Simon,
I did find a good one last year I think, but unfortunately I have upgraded the computer and seem to have lost the link. I'll try to find it.
Got to be frank, I find a lot of the modern stuff seems to make things far to complicated. I suppose Plumbing in its basic form is not that complicated really.
It does have lots of things to remember though and I think its the sheer amount of things you have to learn, that people new to the trade find a bit daunting.
Especially as most Plumbers seem to learn on theoretical courses these days to gain qualification.
In my day you did more hands on. It was simple really, the employers got paid for things you made not those you theorised about.
In other words you could install a bathroom suite, using 22mm and 15mm pipe but never knew until much later why you used that size pipe.
So in my day the practical took precedent over the theoretical.
Today Plumbers seem to be full of theory but have trouble with the practical.
We also learnt a lot through our own observation.
You learnt to look at something and instinctively knew something was wrong.
Probably having seen so many systems of the same type you had built up a common behaviour pattern of how they should work in your mind. So that any you came across that was not following the normal pattern of behaviour, probably had something wrong.
In reality of course Plumbing is a mixture of both theory and practise. It simply takes time to get the balance right and you don't always do so, your always learning. I am retired now and worked on all kinds of jobs and different sorts of Plumbing, but I am still learning.
What I did find over the years though, is to try and think simple. The more you go into the theoretical side the more complicated things can seem and perhaps stop you from being able to do simple things.
Do we really need to understand things at the sub atomic level for a Plumbing job?
Its nice to know of course, but you can over do it I think.
Anyway, I will keep looking and post the addresses of any free books on the net I find.
As to more modern books, but fairly easy to understand, try G.J Blower Plumbing Mechanical Services Part 1 and 2 it seems to help. Look on e-bay for it,expect to pay a couple of quid thats all.
But also look for older books of the simple type, there seems no point in getting a book that you can't understand and don't be afraid to say "I don't know or I don't understand" try another book, it may explain it in a way you do understand.
Even as an adult, if I wanted to learn to read, I would hope I would start with first year kids books not Shake spear and I would not be afraid to be seen reading them either.
Its learning to read I was trying to do not pose with a book I couldn't.
I often download pages and pages on the same topic to gain some idea of what its about. All its about is matching how you learn to how its being taught.
Avoid the trap of thinking "Wow that is too complicated for me to learn!" it may just be the way its being explained that you can't take in, not that you would not perhaps understand it if it where put another way.
Good Fortune
Bernie