In message , T i m
writes
On Sat, 30 Sep 2017 08:45:58 +0100, Chris J Dixon
wrote:

T i m wrote:

I think this whole renewable's thing is like the double glazing thing
of years gone bye. Yes, you can reduce draughty windows and never have
to pain them (good thing IMHO) but you then get issues with damp,
mould, respiratory diseases and are forced to have a fixed trickle
vent to get the draught back ... ;-(

Yes, it is a pity that whole house ventilation with heat
exchanger isn't a cost-efficient or practical retro-fit.


I considered making something myself for the bathroom (the only part
of the house with a cavity wall where it might be worth doing such a
thing).

They already exist. My wife had a rented out flat which was fine until a
very clean family moved in. Lots of showers and clothes drying led to
condensation mould near the top of the North facing walls.

Luckily the ducting already existed from the previous *off peak* heating
distribution.

Downsides are the background noise from the fan and the routine cleaning
maintenance.

You can get self contained wall mounted ones for bathroom extract
locations.

Extract the air though the ceiling, out though a baffle box of some
sort (big heatsinks bolted back to back in the in / out airways) and
then to a split or pair of vents etc?

I think I understand these things can be no more than 50% efficient
(would a heat pump make that better somehow) and you have to consider
any condensate and things getting blocked etc (so may warrant
cleaning).

I'm assuming there is a good reason that such solutions aren't std
practice still. Diminishing returns?

--
Tim Lamb