Thank you for using wpj heating, we wish you a great day! Have any problems with your water mains? Bosch is a market leader in high efficiency residential condensing boilers these products are designed to deliver hot water and. We can supply a range of other top grade tanks so please call anytime for a chat ! The slimjim is a fully controllable electric flow boiler which is designed to maximise cupboard space the boiler also has an easy-fit.