Personally if a system is retained, even if it is to an older standard, I would expect it to be fully working, so if it has a water motor gong then that should still function. Traditionally I would have thought one of it's purposes is to warn passers by of a fire out of hours hence their installation on outside walls, although if the building fire alarm is monitored it could serve the same purpose (more effectively).
One caution with old systems is not to over-rely on them as much and to ensure tenants don't in FRAs as often the premises bear little resemblance in layout and risk to the original use and the systems are not always resurveyed and re-engineered appropriately to suit this. Also few users have service staff carry out a full audit as per the BS and service visits early venture outside the valve chamber, missing the numerous blocked, painted and poorly positioned heads around the site.
That and water supply issues mean that there is a greater chance of the system failing to contain a fire and care needs to be taken on how much weight you give to the presence of a system.
Most of the old systems from the big former single occupier industrial premises that date from the 1900-1970's period simply get drained as users won't pay for upkeep & re-engineering if there is no absolute requirement to maintain them, which as most were for property not life is often the case & insurers don't seem bothered about their removal for normal risks, so it's refreshing to hear of a site that is retaining them.
