In article ,
polygonum_on_google wrote:
On Wednesday, 13 January 2021 at 17:33:06 UTC, Chris Green wrote:

To my mind there are three different types aren't the-

Conventional - with a flue going up a chimney or similar, draw air
from room

Balanced Flue - Both air in and fumes out go via a hole in the wall,
no need for chimney, doesn't draw air from room

Flueless - No flue of any sort, draws air from room, exhausts to room.
Needs careful design to be sure gas fully burnt to CO2, needs good
ventilation.

Yes - that is exactly what I am aware of.

The one I find difficult to understand them not installing is the
balanced flue. After all, they are not that different to some boilers.

ISTR - from 50+ years ago - that tehre were various requirements about
distance from opening windows, doors, etc. It may be that with smaller
houses they are becoming very difficult to fit and comply with the rules.
There might be a lot of paperwork, too. And then there's cutting quite a
large hole in the wall. not really a plumbing job.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle