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AOV question regarding degrees vent must open

Tony J

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Hi All

We manage a block that has two stairwells with one AOV in each stairwell. The maintenance company have since told me the openings do not conform (this is some 5 years after installation, it has passed every service) as they do not open to 140 degrees; and they want to replace the whole system at a cost of ~3k per vent

Having spoken to some other companies there does seem to be disagreement about whether this sort of opening is required (they open to about 60 degrees, 1m x 1m vent)

Does anyone have any input please?

Thanks in advance

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My interpretation a 1m2 free area ventilation is required by Approved Document B (fire Safety) volume 2: Premises other than Dwelling Houses (item 2.26 page 29) at the head of each staircase. To measure the free area you need to check out appendix C 5 free area of ventilators. You have two choices and I am not sure you will achieve 1m2 by either, you need to speak to somebody who specialise in NSHEV systems.

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  • 1 year later...
Guest santosgb@aol.com

I know its super late... however someone may find it helpful. 

Do they do commissioning of the new system or routine inspection and maintenance


BS 7346-8, 9.2 Routine inspection and maintenance.... have nothing to do, AND I MEAN nothing,  with whether system conforms or not. ITS MERELY to test EXISTING install AS IS, AS BUILD in the past. They act like they were specifier or risk assessors.

FYI Same principle is applied to fire alarm system (except situation where new company takes over the contract if such company is appointed at all, some relay on one off fire technician.  Another exception would be an Emergency lighting where each periodic (yearly) test asses design and any shortcomings must be improved (I am talking ones which would adversely affect safety, not missing LOG BOOK or manuals).Additional lighting next to FIRE equipment for example for example to get required 5lux for example. It doesn't matter that some moron issued certification "last year". Now YOU do it so make sure its right, its your liability, and regs call for design reassessment each time.

I do apologize for such lengthy answer, i could just say: money making scheme, or perhaps something more in line with government: job creation scheme.

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