Do not put photoelectric smoke alarms in the ceiling cavity of an old house...

Forums › Home Workshop DIY › Do not put photoelectric smoke alarms in the ceiling cavity of an old house...

timmmay

15238 posts

Uber Geek

Trusted

Subscriber

# 243732 29-Dec-2018 06:59

... because they can go off at random times between midnight and 6am, and because it's up high you have a heck of a job working out where it's coming from. I guess it was dust in our ceiling cavity, or a mouse pushing the test button...

That is all.

Jase2985

8874 posts

Uber Geek

Lifetime subscriber

# 2151720 29-Dec-2018 07:24

they will be getting dust in them which will cause them to go off

why would you have one in the ceiling cavity anyways?

timmmay

15238 posts

Uber Geek

Trusted

Subscriber

# 2151721 29-Dec-2018 07:29

Jase2985:
they will be getting dust in them which will cause them to go off

why would you have one in the ceiling cavity anyways?

In case a fire started up there. I had it spare.

I guess the other type may be more effective?

sbiddle

28269 posts

Uber Geek

Moderator

Trusted

Biddle Corp

Lifetime subscriber

# 2151724 29-Dec-2018 07:33

One person supports this post

I've never heard of anybody ever installing a smoke alarm in a roof space and it's a bad idea for the reason you've discovered - the roof space is full of dust so they're going to trigger continually when dust enters the chamber. Both ionisation and photoelectric alarms will suffer this issue.

timmmay

15238 posts

Uber Geek

Trusted

Subscriber

# 2151727 29-Dec-2018 07:40

I just figured "why not?". And now I know.

Goosey

1848 posts

Uber Geek

Subscriber

# 2151730 29-Dec-2018 07:44

you are better off installing wired smoke alarms that intergrate with your home security system. Then all you need to do is use the keypad to hush them.

Eitherway... one in the roofspace will keep you awake regardless.

I wonder how HRV (ventilation gumps), do it with their systems? (perhaps that smoke alarm is a really small one and focussed on the motor).

timmmay

15238 posts

Uber Geek

Trusted

Subscriber

# 2151736 29-Dec-2018 07:48

We have a central smoke alarm attached to the alarm system between our bedrooms in the hallway. I've put extra smoke alarms in the bedrooms and kitchen so we get earlier warnings if there is a fire. I could get more wired in, I think I have a couple more slots on the alarm available, but because I already got standalone ones which will be a bunch cheaper I bet.

k1w1k1d

616 posts

Ultimate Geek

# 2151748 29-Dec-2018 08:54

One person supports this post

I have always thought that smoke alarms in the ceiling cavity would be a good idea. It is a hot dry dusty place with lots of electrical wiring etc. so is probably an area that fires could start in. Trouble is that those conditions also make it an unsuitable place to install smoke alarms.

irongarment

281 posts

Ultimate Geek
Inactive user

# 2151785 29-Dec-2018 11:07

You could put a heat alarm up there (as recommended for kitchens).

timmmay

15238 posts

Uber Geek

Trusted

Subscriber

# 2151787 29-Dec-2018 11:13

Probably won't bother. It can get up to above 40 up there in summer.

irongarment

281 posts

Ultimate Geek
Inactive user

# 2151790 29-Dec-2018 11:18

Good point. I'm planning to put a DS18B20 temperature sensor up there as I extend my 1-wire network throughout the house. I'm curious to see how hot it really gets on a sunny summer's day.

mdf

2328 posts

Uber Geek

Trusted

Subscriber

# 2151800 29-Dec-2018 11:31

The other problem with this is when the battery goes flat and it starts emitting a cheeping reminder noise.

We were in a hotel once when this happened to us. Took the staff forever to figure out that it was coming from a smoke alarm in the roof cavity. Much surliness on all sides ensued.

timmmay

15238 posts

Uber Geek

Trusted

Subscriber

# 2151815 29-Dec-2018 11:34

I have an annual reminder to check smoke alarms including batteries.

Jase2985

8874 posts

Uber Geek

Lifetime subscriber

# 2151828 29-Dec-2018 12:16

One person supports this post

timmmay: I have an annual reminder to check smoke alarms including batteries.

its called daylight savings, happens 2x every year

richms

22524 posts

Uber Geek

Trusted

Subscriber

# 2151873 29-Dec-2018 14:05

I have logged a fraction over 60 in my roofspace at the top underneith the black metal tiles. I would expect that would cook any battery in no time if it was a battery alarm.

Also all the smoke that blows thru there from the neighbours fires would set it off in winter.

Richard rich.ms

jarledb

Webhead
2292 posts

Uber Geek

Moderator

Trusted

Lifetime subscriber

# 2151953 29-Dec-2018 17:47

richms:

I have logged a fraction over 60 in my roofspace at the top underneith the black metal tiles. I would expect that would cook any battery in no time if it was a battery alarm.

Also all the smoke that blows thru there from the neighbours fires would set it off in winter.

In addition: Most heat sensors will go off around 58 degrees Celcius. The smarter ones will look at how quickly the temperature changes, but any fairly cheap heat alarm would probably just alarm when it passes 58 degrees.

Jarle on Twitter - Senson NZ - WordPress experts