Sprinkler repairs: leaks, seized valves and damaged heads

Sprinkler systems fail in a small number of predictable ways, and almost none of them are the sprinkler head deciding to let go. Knowing which fault you have decides whether it is a callout tonight or an item on the next service visit.

What actually breaks

Corrosion in the pipework. The commonest cause of a leak on any system more than fifteen years old, and the one that gives least warning. Wet pipe systems corrode from the inside where water sits still; dry systems corrode worse, because trapped water and air together are more aggressive than water alone. It shows as a weep at a fitting or a stain on a ceiling tile long before it shows as a burst.

Valves that seize or pass. A gate valve nobody has turned in six years does not turn cleanly, and an alarm valve with a worn seat passes a trickle that keeps the jockey pump running. Both are found by the annual service when the valve set is stripped, which is why “stripped” and “inspected” are different words on a quotation.

Impact damage to heads and pipework. Overwhelmingly the cause of accidental discharge. A forklift mast, a scaffold pole, a pallet pushed into a clearance zone, a contractor hanging something off a sprinkler pipe because it was the nearest steel.

Flow switches and pressure switches. They fail silently. The system still works; it simply stops telling anyone it has. This is the fault the quarterly test exists to catch, and it is the interval most often skipped.

Failed trace heating on any pipework in an unheated space, which turns into a split pipe at the first hard frost.

The one thing never to do

Never tighten a weeping sprinkler head.

A head is a sealed assembly, listed and set at the factory. There is no gland to nip up. Turning it does not reseat anything, and on a head holding mains pressure it can shear the plug straight out. A drip becomes a full discharge with somebody standing under it.

The same applies to heads that have been painted, knocked, or had anything hung from them. They are replaced, from the correct spares for that installation, at the correct temperature rating. A cabinet of spare heads that do not match the ceiling is not spares, which is why the annual service checks them.

What a repair actually involves

More than the fix itself, and this is where the time goes.

1. Identify and isolate. The affected section is isolated at the nearest subsidiary stop valve, so the rest of the building stays protected. A system with zone valves loses one floor; a system without them can lose the lot.
2. Tell the right people. The responsible person knows the system is down, and in most cases so does the insurer. Depending on the building and how long the work takes, a fire watch may be needed while it is out.
3. Drain, repair, refill. Draining takes longer than people expect on a tall building, and refilling has to be done with the air vented properly or the system comes back with air locks in it.
4. Recommission and prove. Pressures back to normal, the valve set proved, the alarm tested, and the system confirmed back in service in writing.
5. Record it. The defect, the repair, the isolation period and the return to service all go on the record. That record is what turns “the system was off” into something defensible.

Steps two and five are the ones contractors skip and the ones an insurer asks about. What that evidence needs to look like is in what your insurer wants to see.

Emergency, or next visit?

A rough division, and when in doubt ring rather than decide.

Now. Water discharging, a head that has operated, a burst or a running leak, a pump that will not start, a system that has shut itself down, or any fault that has taken the installation out of service. Anything in this list means the building is currently less protected than its fire strategy assumes.

Soon. A weeping head or fitting that is contained, a valve that is stiff, a flow switch that failed its test, a jockey pump cutting in every few minutes. None of these has taken the system out, and all of them will get worse.

Next service. Corrosion noted but not leaking, missing signage, a spares cabinet that needs restocking, minor obstructions.

That middle category is where money is saved. A jockey pump cycling constantly is the system telling you there is a leak somewhere, and finding it in daylight costs a fraction of finding it when a ceiling comes down. Why that happens is covered in our guide to fire pumps.

What you can do without a contractor

Genuinely useful, and none of it needs a spanner:

• Log the gauge readings weekly and look at the trend, not the number. A slow drop is a leak.
• Walk the floor once a year looking up, at clearances below heads and anything installed since last time.
• Report the drip immediately, and do not let anyone tighten it.
• Check the spares match the heads actually fitted.
• Keep the valve status record, so nobody has to guess whether a strapped valve was meant to be shut.

Everything past that needs somebody competent in sprinkler systems, because a valve set reassembled wrongly leaves the installation shut and looking perfectly normal.

If something is discharging now, ring rather than read: that is 24/7 emergency call-out. If it can wait, it belongs on a sprinkler servicing visit.