Combi to fit in a kitchen wall unit....

[bengasman]

Thanks. The Glowworm Flexicom 30CX seems to fit fine.

Would this be preferable to the Isar 30HE?

Both are likely to become a long lasting nightmare.

There is no reliable combi that fits in a standard kitchen cupboard, it's that simple. The question has been posted dozens of times, and all options have been chewed up and regurgitated.

If you want a reliable boiler, you will have to choose from 3 options:

move the boiler to where you don't see it.
just accept you can see the boiler
get a bespoke cupboard