Oh, and I have a cat - but have not yet worked out where to put the catflap, let alone make it airtight - so perhaps ventilation will be maintained by the cat anyway

Getting it signed off may be another issue, but at the rate my build is going it may be 10years before I get to the point where it matters, so am considering self installing for now and reconsidering my options at the time of sign-off, but even with an ASHP I'm tempted to have a WBS 'cos it'll work even when the HP / electric goes belly up , and with a 30acre smallholding I do have a lot of fuel just from hedge maintenance.
I was given the dovre as both I and the chap who gave it to me assumed it was 'smaller' than the esse, in kW not just physical size, but I sort of prefer the esse anyway even though it'll take up a lot of space, and for some reason I have more confidence that I can reduce the firebox of the esse and keep it working.
Hi Ken - glad to hear the immersun is still working - I had wondered

I do have about 10 old storage heaters and the bricks from a few more, so yes, I was indeed thinking of installing them somehow - I've been watching Joeboys experiments with interest.