Manual smoke vent controls

[NickCSL]

Hi

I'm looking for some clarification about the need for and locations of manual smoke vent controls in a four-storey single-staircase property with protected lobbies.

Smoke detectors are installed in the lobbies only. On activation AOVs in both the staircase and lobbies open. There is no audible alarm.

Where should the AOV manual override switches be located?

NS

[AnthonyB]

Stair vent manual controls should ideally be at fire service access level (some lazy installers put it at the stair head) and lobby vent controls in each lobby. Sounds like the system is configured dangerously wrongly if all lobby vent doors open - I suggest you try the following:
 

Quick guide to checking whether your smoke shaft system operates in this manner:

1. Actuate a lobby or corridor detector;
2. Check that the shaft AOV opens only on that floor and the damper at the top of the shaft (likewise the base of the shaft if provided);
3. Without resetting the system proceed to another floor and repeat the test, nothing should happen i.e. no other AOV should open;
4. Repeat as you feel necessary, to ensure have a good sample;
5. Without resetting the system, find a manual override switch for another floor AOV (associated with the same shaft) and activate it, again nothing should happen;
6. Have the system reset, any AOVs that opened should now close;
7. Finally check all AOVs are close fitting and if they are fire door type, check the adequacy of the intumescent strips and smoke seals.

 

[NickCSL]

We have no manual controls whatsoever!

 

So a switch is needed at the main entrance to operate the staircase AOV, and switches needed in each lobby to operate the lobby AOVs.

 

Does that mean a switch is not needed at the top of the stairs to operate the staircase AOV?

 

Are you able to point me in the direction of the regulations re this? The contractor we had hoped to use has said we need a control at the top of the stairs and if this isn't necessary we'd like to avoid the additional expense. Interestingly he neglected to say we need controls in the lobbies, so it looks like this is already going to cost more than expected ?.

 

We need to get this right first time!

 

NS

[AnthonyB]

More important than the manual controls are the Cause and Effects for the various vents - if they don't operate as indicated above there will be spread of fire between floors, will be serious property damage and potential for loss of life: https://www.ife.org.uk/Firefighter-Safety-Incidents/2016-regents-quay/39930

BS 7346 is the standard systems should be installed to and specific guidance to residential systems is here http://www.smoke-vent.co.uk/documents/SCA Guidance notes rev 3 (Jan 2020).pdf

Smoke control systems are a specialist area and many electricians and fire alarm firms get involved with them despite not being fully aware of what is required and the advice of a smoke control specialist should be sorted.

[NickCSL]

Thank you ?

I'll definitely make sure the system is properly checked to ensure it's configured properly.

[Meady]

On 29/01/2021 at 19:15, AnthonyB said:

More important than the manual controls are the Cause and Effects for the various vents - if they don't operate as indicated above there will be spread of fire between floors, will be serious property damage and potential for loss of life: https://www.ife.org.uk/Firefighter-Safety-Incidents/2016-regents-quay/39930

BS 7346 is the standard systems should be installed to and specific guidance to residential systems is here http://www.smoke-vent.co.uk/documents/SCA Guidance notes rev 3 (Jan 2020).pdf

Smoke control systems are a specialist area and many electricians and fire alarm firms get involved with them despite not being fully aware of what is required and the advice of a smoke control specialist should be sorted.

Just supporting Anthony's comments re. electrician / alarm engineers fitting smoke vents - we had a brand new block of flats built last year with all bells and whistles...but, at sign-off / handover stage, the Building Control Officer luckily spotted the fact that no manual controls for the ventilation system had been fitted at all...also, after further cause and effect testing, we noted that the AOV's opened on every single floor (20+ storey building).... we ended up (at some considerable expense) finding a competent contractor who specialised in smoke ventilation systems sorting this out for us.  

Lesson of the day...learn from others mistakes! ?

[Guest Big Al]

How do you test the fireman's override at the entrance to your building, supply and extract and what exactly does it do?

[AnthonyB]

There are many firemans switches for many things - is this a yellow box that looks similar to a fire alarm call point but has a three position key switch marked something like "normal/off/extract" or "open/auto/close"

[Guest Paul]

Smoke Ventilation Manual override switches are normally located next to the the vent being tested, this is so you can make sure it opens/closes correctly and that no one has stuck a body part in the vent being closed.

If the vent is high level then the switch can be else where, but we would recommend it being near the high level vent or in a position that you can see the vent during operation in case anything was to go wrong with the vent, ie: roof vent and the switch being located bottom of an open staircase.  

As an example, we have one site where the roof vent has two folding arm actuators, one works the other was faulty, luckily the override switch was in a position to observe the operation of the vent and we could shut it down before any damage was done to the vent, these arms have a lot of force behind them.

I hope this helps.