On 18/05/2019 11:22, Dave Plowman (News) wrote:
A non balanced flue boiler is going to be about as inefficient as they
come.

Not necessarily.

My house, like millions of others, had a BAxi Bermuda back
boiler (about 15Kw) with a 3/6 Kw radiant fire.

The flue was Class 2 flue blocks built into the inner leaf
of the cavity wall, which passed through the upstairs front
bedroom and kept that North-facing room quite comfortable on
its own.

Even the radiator was only half the size of the other,
in a south facing bedroom.

If the original numpty builders hadn't chucked the cement
snots inside the flue blocks and mortared the joints correctly
I might still have it today, but eventually the metal work
that directs the gas fire flue into the main flue corrodes
and then the fire is condemned even if the boiler works fine.

Oddly enough, a neighbour fell for the BG boiler scam and
allwoed them to remove their back boiler and fit a WB
condenser in an upstairs bedroom cupboard. They also removed
all the flue pipe work that connected to the
ridge tile (the class 2 blocks had been replaced with
aluminium single skin stuff that had to be boxed in where
it passed through the bedroom, many years earlier).

However, despite removed ALL the flues, they left the
gas fire and told them they could still use it (even
without a flue ??). They are still alive so I guess they
only use central heating.