On Wed, 24 Aug 2011 10:03:47 -0700 (PDT), "
wrote:


2 storeys, old chapel converted to domestic use.
All 4 bedrooms have doors, 2 upper floor, 2 lower floor - all open
into the open plan area (and have means of escape windows as well).

There's a modern oil-fired Rayburn in the kitchen (ground floor, with
doors) - which also has heat-sensitive cut-off valves for the oil

I'd certainly put a heat detector above that.

The upper floor smoke detector wiring is already behind plasterboard,
consists of single point outside the bedrooms, above one door - and
within 1.5m of the other door - also well exposed to the main space
with the woodburner.

The upper floor detectors are far more important than lower floor
ones, especially with a large void.

The lower floor wiring could still easily be changed, and consists of
two points just inside and above the kitchen door (where I had planned
to fit a heat detector and a CO detector), - and one point under a
landing which is a natural catchpoint for smoke from the woodburner.

I'd put a heat detector above the stove (not by the door). I'm not
sure why you want a CO alarm. Under the landing may be the location
which would produce nuisance alarms so try that with a battery unit
first.

Another point the OP has drawn attention to - is placing them at a
height to make them accessible for cleaning - which is a particular
issue here.

Yes - and they don't work well mounted on walls, you get a barrier
layer and smoke rises a few inches out from the wall.

Is it likely to be an effective solution (I would have to read up if
it meets regs) to have smoke detectors in each bedroom, and only a
heat detector in the main space with the woodburner?

Smoke detectors in bedrooms are only really useful if you have someone
who smokes in bed. If the door is closed it will alarm far too late
on a fire outside the room. (The other use for an interlinked alarm
inside a bedroom is simply to extend the alarm to wake people up - it
will never trigger on its own detector)

Finally, what are the relative merits of rising-rate and fixed-point
heat detectors?

Rising rate detect a fire a bit earlier on, they look for quite a fast
rise over a short time, typically about 10deg C a min. They don't
care what the absolute temperature is. They are good at detecting
things like chip pan fires or oil boiler fires.

Point detectors require a trip temperature to be reached. Usually
about 60-70 deg C. Point would usually be used in places like boiler
rooms which can have fast temperature variations in normal operation.
They are also appropriate in kitchens where there are high rates of
change of temperature (a cooker near a back door for example where the
door opening and closing can produce fast changes in temperature).