Thanks gents - you've convinced me that I shouldn't go for an unvented cylinder and I've an underlying uneasiness that flow/pressure of my mains could deteriorate in the future which would turn my unvented system from 'just about okay' to 'completely useless'. There are plans to build a couple of thousands houses in my relatively small town so who knows what could happen in the future.
Therefore I'm going full steam ahead on the vented cylinder plan with a pump. I've been in touch with Stuart Turner support who are as good as everyone says there are, but was wondering if either of you could advise what size of cold and hot water cylinders I should be looking at to give me a bit of headroom as the family grows up (currently 1 toddler and one on the way - no plans for anymore!). I've just been up in the roofspace as the current cold water tank is 50 gallons, as I've said before the hot water cylinder is currently 140 litres. We are looking to be able to run decent showers off these, maybe around 15 litres / minute
Therefore I'm going full steam ahead on the vented cylinder plan with a pump. I've been in touch with Stuart Turner support who are as good as everyone says there are, but was wondering if either of you could advise what size of cold and hot water cylinders I should be looking at to give me a bit of headroom as the family grows up (currently 1 toddler and one on the way - no plans for anymore!). I've just been up in the roofspace as the current cold water tank is 50 gallons, as I've said before the hot water cylinder is currently 140 litres. We are looking to be able to run decent showers off these, maybe around 15 litres / minute