smoke alarms ....

No. Neither have significant false alarm rates. Both however can suffer nuisance alarms, these are not false alarms but real alarms produced by non- dangerous activities such as steam from a bathroom or overheated toast.

Optical suffer more from steam, ionisation from the combustion products of things like singed toast. Used and sited properly neither should have a significant nuisance alarm rate (unless of course you are prone to overheating toast with the toaster is in the bathroom sink while you are taking a shower).

There are different types, at least 3, of detectors which are recommended for different rooms/areas for just the reasons you say. Placing the right one in the right location/checking it has been done is the kind of thing I'd expect a competent Building Inspector to be able to do. May be a call to the local council?

This may help:

I went for a compromise:

FireAngel ST-622:

Your local FPO would be a better source of advice.

If you are getting regular false alarms like that then you aren't cooking your food you are burning it to a cinder with associated risks of making carcinogenic compounds like acrylamide in the resulting char.

Which Sept 2018 has a review of Smoke Alarms. (Sorry, can't seem to find a pdf of it to post: will keep looking)

An alternative hypothesis is that he is cooking food with flavours which he enjoys, despite such warnings, in order to enhance his quality of life and increasing the sum total of his quality-adjusted life years (QALYs)[1]. I'd call that sensible DIY QALY control.

He may also be doing so in full knowledge that the warnings about acrylamide are based largely on the precautionary principle.

And when you say "burning it to a cinder" he - like me - might say "triggering the Maillard reaction".

Now I'm off to have another strong coffee. Full of acrylamide. But where even the FDA don't think a warning is needed. As confirmed only last month in a much more even comment on the issue.

[1] for this purpose I use QALY to mean not just a year in "perfect health" but also with desired level of happiness.

All a building inspector will do is point you Volume 1 of Part B of the Building Regulations

which says :-

Positioning of smoke and heat alarms

1.10 Detailed guidance on the design and installation of fire detection and alarm systems in dwellinghouses is given in BS 5839-6:2004. However, the following guidance is appropriate to most common situations.

1.11 Smoke alarms should normally be positioned in the circulation spaces between sleeping spaces and places where fires are most likely to start (e.g. kitchens and living rooms) to pick up smoke in the early stages of a fire.

1.12 There should be at least one smoke alarm on every storey of a dwellinghouse.

1.13 Where the kitchen area is not separated from the stairway or circulation space by a door, there should be a compatible interlinked heat detector or heat alarm in the kitchen, in addition to whatever smoke alarms are needed in the circulation space(s).

1.14 Where more than one alarm is installed they should be linked so that the detection of smoke or heat by one unit operates the alarm signal in all of them. The manufacturers? instructions about the maximum number of units that can be linked should be observed.

1.15 Smoke alarms/detectors should be sited so that: a. there is a smoke alarm in the circulation space within 7.5m of the door to every habitable room; b.they are ceiling-mounted and at least 300mm from walls and light fittings (unless, in the case of light fittings, there is test evidence to prove that the proximity of the light fitting will not adversely affect the efficiency of the detector). Units designed for wall-mounting may also be used provided that the units are above the level of doorways opening into the space and they are fixed in accordance with manufacturers? instructions; and c. the sensor in ceiling-mounted devices is between 25mm and 600mm below the ceiling (25-150mm in the case of heat detectors or heat alarms). Note: This guidance applies to ceilings that are predominantly flat and horizontal.

1.16 It should be possible to reach the smoke alarms to carry out routine maintenance, such as testing and cleaning, easily and safely. For this reason smoke alarms should not be fixed over a stair or any other opening between floors. 1.17 Smoke alarms should not be fixed next to or directly above heaters or air-conditioning outlets. They should not be fixed in bathrooms, showers, cooking areas or garages, or any other place where steam, condensation or fumes could give false alarms. 1.18 Smoke alarms should not be fitted in places that get very hot (such as a boiler room) or very cold (such as an unheated porch). They should not be fixed to surfaces which are normally much warmer or colder than the rest of the space, because the temperature difference might create air currents which move smoke away from the unit.

Power supplies

1.19 The power supply for a smoke alarm system should be derived from the dwellinghouse?s mains electricity supply. The mains supply to the smoke alarm(s) should comprise a single independent circuit at the dwellinghouse?s main distribution board (consumer unit) or a single regularly used local lighting circuit. This has the advantage that the circuit is unlikely to be disconnected for any prolonged period. There should be a means of isolating power to the smoke alarms without isolating the lighting 1.20 The electrical installation should comply with Approved Document P (Electrical safety).

1.21 Any cable suitable for domestic wiring may be used for the power supply and interconnection to smoke alarm systems. It does not need any particular fire survival properties except in large houses (BS

5839-6:2004 specifies fire resisting cables for Grade A and B systems). Any conductors used for interconnecting alarms (signalling) should be readily distinguishable from those supplying mains power, e.g. by colour coding.

Note: Mains-powered smoke alarms may be interconnected using radio-links, provided that this does not reduce the lifetime or duration of any standby power supply below 72 hours. In this case, the smoke alarms may be connected to separate power circuits (see paragraph 1.19)

1.22 Other effective options exist and are described in BS 5839-1:2002 and BS 5839-6:2004. For example, the mains supply may be reduced to extra low voltage in a control unit incorporating a standby trickle-charged battery, before being distributed at that voltage to the alarms.

Design and installation of systems

1.23 It is essential that fire detection and fire alarm systems are properly designed, installed and maintained. Where a fire alarm system is installed, an installation and commissioning certificate should be provided. Third party certification schemes for fire protection products and related services are an effective means of providing the fullest possible assurances, offering a level of quality, reliability and safety.

1.24 A requirement for maintenance cannot be made as a condition of passing plans by the Building Control Body. However, the attention of developers and builders is drawn to the importance of providing the occupants with information on the use of the equipment, and on its maintenance (or guidance on suitable maintenance contractors). See paragraph 0.11. Note:

BS 5839-1 and BS 5839-6 recommend that occupiers should receive the manufacturers? instructions concerning the operation and maintenance of the alarm system.

I would read the Ei Aico website - lots of deployment info on there.

I have their alarms - mains interlinked: CO, heat, mostly ionising but possibly one optical (I forget).

The only false alarms I have every had were:

1) Hoovering out the dust - stops as soon as hoover removed;

2) Heat gun paint stripping - impressive, no visible smoke;

3) Soldering water pipes.

4) Couple of times cooking smokey dishes (searing beef) - heat detector locally, so must have got to the hall alarm...

I'd say they do a remarkable job with very little nuisance.

Well, ionising ones tend to spot invisible things if they change the conductivity of an ionised area in the sensor, but optical ones presumably have the band set to attempt to detect most smoke particles. I guess in the end it depends what is burning. I'd suspect that tiny toast burns might produce larger particles than something like a smouldering item, but I've not tested it. Presumably all must conform to some kind of standard and how can one tell if smoke is from burned toast or a real fire in the end? Brian

No but one added thing to take into account. Most people tend to site them on the ceiling. This is not a good idea if you have to climb to change a battery or stop it sounding cos you burned the toast. I have one half way up the stairs which may mean it gets more toast falls alarms but is easy to shut up without getting a ladder or falling. Brian

Good grief you poor innocent soul. Half of our lot cannot tell the difference between carbon monoxide and smoke alarms. Brian

A suitable length stick will allow a reset without climbing. Can't change a battery that way though. The ones the fire brigade fit for the elderly in Manchester are one time usage with no replaceable parts (which seems a shame to me). They are scrapped typically every 4 years.

The only time mine or the Village Hall ones false alarm is on days like today when real smoke from someone's coal fire nearby gets wafted into the building through an open door. The main mode of failure is a low battery alarm panic in the middle of a cold winter's night consisting of an annoying loud chirp every couple of minutes. Too loud to ignore.