Every winter we take calls from building owners who have found a split sprinkler pipe the hard way: water through a ceiling, stock ruined, and a system that would not have worked if a fire had started that night. Almost all of these failures are avoidable. A little preparation in November saves a great deal of disruption in January.
Why cold weather is a problem for sprinklers
Most sprinkler systems in the UK are wet systems. The pipework is full of water at all times, so a sprinkler head discharges the moment its bulb breaks. That speed is what makes them so effective, but it also means the water in the pipes is exposed to whatever temperature the building drops to.
When water freezes it expands. Inside a closed pipe that pressure has nowhere to go, so it splits fittings, cracks valve bodies and can even force a sprinkler head to open. Two problems follow. While the ice is there, the affected part of the system cannot deliver water. When it thaws, water escapes from the damage, often in a part of the building nobody is watching.
Designers plan for this from the start. Wet pipework belongs in spaces that stay heated, and most work to a minimum of around 4°C. Where a building, or part of it, cannot be kept warm, a dry system or an alternate wet and dry system is used instead, with the pipes filled with compressed air until a head operates. The trouble usually starts when a building is used differently from the way it was designed: heating turned down to save money, a unit left empty, or a new opening that lets the cold in.
The places that freeze first
In our experience, frozen pipework is rarely found in the middle of an occupied office. It turns up in the edges of a building:
- Pump houses and tank rooms. Often separate from the main building, with a small heater that nobody checks until it fails.
- Valve rooms and sprinkler control areas. If the main control valve freezes, the whole system is affected.
- Loading bays and goods in areas. Roller shutters left open for long periods let freezing air straight onto the pipework.
- Roof voids, plant rooms and stairwells. Unheated by design, and easy to forget.
- Pipework close to external walls, windows and vents.
- Empty or partly occupied buildings. Vacant floors, units between tenants and sites closed over Christmas are all at higher risk.
Practical steps before the cold arrives
Check the heating in every space with wet pipework
Walk the building and confirm that every area containing water filled pipework is heated, including the ones you rarely visit. Test frost thermostats and heaters in pump houses and tank rooms, and make sure they are on a supply that will not be switched off with the rest of the building. A simple wireless temperature sensor with an alert is cheap insurance for a remote pump house.
Look at insulation and trace heating
Exposed lengths of pipe in vulnerable spots can be lagged, and in some cases protected with electric trace heating. Trace heating needs its own checks: a failed circuit gives no protection while looking exactly the same as a working one. If you are not sure what is fitted or whether it still works, ask your sprinkler contractor to check it as part of the winter service.
Drain the low points on dry systems
Dry systems are designed for cold spaces, but they are not immune. Condensation and water left behind after a test or a trip collects in low points in the pipework. Those auxiliary drains need emptying, especially before and during cold spells. Air compressors and pressure alarms should be checked so that a slow leak is spotted early.
Keep doors and shutters closed
It sounds obvious, but a loading bay door left open overnight in January can take an area below freezing in a few hours. Remind site teams, cleaners and security staff, and consider door alarms or automatic closers in high risk areas.
Plan for shutdown periods
If your building will be closed over Christmas or New Year, do not turn the heating off completely. Set a frost setting that keeps every space with wet pipework safely above freezing, and arrange for someone to check the building regularly. Insurers increasingly ask about this, and a policy may have conditions about unoccupied premises.
Book your service before winter
A sprinkler service in the autumn is the ideal time to pick up weak spots: heaters that have failed, insulation that has been removed during other works, dry valves that need attention. Our guide on how often fire sprinklers should be serviced explains the routine checks in more detail.
What to do if you suspect a frozen pipe
If you notice ice on pipework, a sprinkler head with frost around it, or a sudden pressure alarm in cold weather:
- Do not use a naked flame or heat gun on the pipe. Uneven heating can crack fittings and damage sprinkler heads.
- Do not shut the system down on your own. If a section has to be isolated, it must be done in a controlled way and recorded, and your insurer and the person responsible for the fire risk assessment may need to know.
- Raise the temperature of the space gradually if you can do so safely.
- Call a competent sprinkler engineer. Eversafe offers a 24/7 emergency service for exactly this kind of problem.
- Put extra fire precautions in place while any part of the system is out of action, such as fire watch patrols and restricting hot work.
Changes of use can change the risk
If a building was designed with heating that is no longer used, or a warehouse has taken on a new tenant who keeps the shutters open all day, the original design may no longer suit the space. In some cases the right answer is to convert part of a wet system to dry or alternate operation. That is a design change and should be carried out by a qualified contractor to the relevant standard, such as BS EN 12845 for commercial and industrial buildings.
We can help
Eversafe Fire Protection designs, installs and maintains sprinkler systems for commercial, industrial and residential buildings across the UK. If you want a winter check of your system, or you are worried about an area of your building that gets cold, contact us and one of our engineers will be happy to advise.