How did you manage to get a competent tradesmen for 150 a day.... although upping it to 200 mid job is a bit much. Although paying someone to come in every now and then when you get paid is bizarre
Looks like a mains fed thermal store to me.
Cold main rises on rhs of cupboard, through scale reducer, nvr and strainer, mini exp vessel then t off to feed thermal store then through mixing valve to outlets
Probably siphoned some of the supply off and diluted the supply for his own gains. Depending on how much he diluted it by, it shouldn't take long to get back to full cv. Ive only ever managed to steal a few days worth all depends how big your van is
Generally for labour intensive lower skilled jobs eastern European workers are better. They turn up and are keen to work. For more skilled trades then it makes no difference- take them as you find them uk and European and you will pay the same rates