It works

Two young workmen in the house for the full day and here they're testing the boiler to see if it works alright and I was allowed to picture them then. The housing association has decided to renew our boilers and today was my turn. They are ever so young these two men, the apprentice just 17 and his master 26. They call themselves 'installers' and not plumbers, altho' they're trained for that job too. 
Seeing the hosepipe in the picture I realize they'd not yet finished the job fully and tested a little later, as water was supplied to the boiler via that pipe; anyway the boiler works alright, I know now and the central heating too as that works from that same boiler.