Have any of you good folks used one of these? At present, I have an immersion heater for hot water to sinks and bath(which is never used except to stand in when having a shower.) I am considering replacing the immersion and putting in heaters suitable for the basin and sink only. Either one feeding the upstairs and downstairs basins, or maybe 2 separate ones. Obviously, the one most likely to be used will be the downstairs kitchen sink. Any opinions please? Thanks x Ps, the shower upstairs is an electric one.