Dear all,

we're planning an extension to the house (a 1960s bungalow), and have
come up with a devious design after many attempts owing to proximity to
the boundary causing restrictions. The design raises a few questions
regarding possible regulations and also some environmental issues
regarding hot water efficiency. Perhaps some of you here might have some
opinions or ideas?

The original house was extended to include a utility room which enclosed
the bathroom window so that the bathroom no longer has any external
walls. The bath extractor fan is vented through the roof (where it meets
the top of an external wall beyond the utility room) via a large plastic
pipe. Our new plan sees an expansion of the utility room and therefore
increases the distance from the bathroom to any external wall and
therefore the required length of ventilation ducting. Are there any
curious regulations about this?

Secondly, the new master bedroom will have an en-suite which will be
right at the end of the house and a full seven meters from the existing
hot cylinder and header tank (which are directly between the bathroom
and kitchen). The concern here is that a silly quantity of water is
wasted expelling all the cold water from seven meters of piping. This
represents a waste of energy and water every time a bath or shower is
taken or when hot water is used at the basin.

Is such waste acceptable? At which point does it become more sensible to
have two separate hot water systems? Perhaps one of those
heat-on-the-fly gas boilers for the ensuite combined with a bit of solar
heating, to produce hot water on demand just for the en-suite?
Alternatively, how powerful/useful/economical/environmental are electric
showers these days?

The water/central heating is rather old but the hot cylinder works well
still. The central heating system is ugly (only one thermostat circuit,
pipes buried in concrete base, two bedrooms plumbed in series, not
parallel!), so some improvements will be made for the extension, but it
would be interesting to know whether people suggest changing the hot
water cylinder for something modern, and if so, what?

Any thoughts, please?

Michael