Back on this one again, last blind lady I did an installatyion for I installed regular styeamer in open vented copnfiguration. Ob viously she can't see pressure guage. I noticed that a firm make an electronic auto filling loop. This opens a connection to the mains electronically when pressure drops to preset point. Not sure this meets wras approval I don't have the wras book though I do have the qualification. In leau of writing to my local board and asking I have devised a similar scheme which includes the AA air gap. Parts required, (all prices ball park figures) Pressure switch approx £8, check valve £2, lift pump £12 break tank (old byelaws kit) £16. Just use small break tank and restrict flow to lift pump so it doesn't run dry. Not a lot of money.