Sprinkler tank float valve replacement at a Kettering packaging factory
Sprinkler tank float valve replacement at a plastic packaging factory in Kettering. The 3 inch valve that refills the sprinkler water storage tank was leaking, so we isolated the infill and fitted a new certified one. The work was carried out by Sentry Sprinkler Protection.
- The problem
- The 3 inch float valve that refills the factory’s sprinkler water storage tank was leaking.
- What we did
- An engineer and an assistant isolated the infill, took the old valve out and fitted a new certified, WRAS approved one, in a single visit.
- The result
- The new valve opened and filled the tank on the day, and the water already in the tank stayed there while the valve was changed.
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ISO 9001:2015 - What these mean
What was wrong, and why it could not wait
The float valve on this factory’s sprinkler tank was leaking. A valve that will not seal lets water run on to the overflow, and a worn valve that starts to stick as well leaves the tank short after it has been drawn down by a pump test or a fire.
The water supply of a sprinkler system is designed around that tank being full, so a faulty infill is not left for the next annual visit. We looked at the valve on site, scoped a straight replacement and came back to fit it.
What does a sprinkler tank float valve do?
A float valve refills a sprinkler water storage tank from the mains. When the water level drops, the float drops with it and opens the valve; as the tank refills, the float rises and closes it again. It is a simple part, and it decides whether the tank is full when the sprinkler system needs it.
BS EN 12845, the standard most UK sprinkler systems are designed to, counts the tank and its refill together as the water supply, and sets a refill time the infill has to meet. A tank that holds the right volume but refills too slowly is not the supply the system was designed around.
How do you know a float valve has failed?
A float valve fails in one of two ways. It passes, so water keeps running in and straight out through the overflow, or it sticks, so the tank stays short after a pump test or a fire has drawn it down. The first wastes water. The second leaves the sprinkler system short of the water it was designed around.
What to look for on your own tank
- Water running from the overflow or warning pipe when the tank is already full
- A level on the gauge that never quite settles
- A level that does not recover after a pump test or a drain down
- A float arm that is bent, or a float sitting low because it has taken on water
- Rust or weeping on the valve body, like the cover plate on this one
Seeing one of these on your own tank? A photo on WhatsApp is the quickest way to show us.
What we did, step by step
Filmed by our engineer on the day, on a phone, with the sound removed.
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Survey and scope
We looked at the valve on site before quoting, and the job was scoped as a straight replacement: a new 3 inch float valve in place of the faulty one, fitted by an engineer and an assistant.
The sprinkler water storage tank, with the ladder up to the roof hatch. -
Isolate the infill
The mains supply to the valve was isolated so the old one could come off. Isolating the infill does not empty the tank, so the water the sprinkler system relies on stayed where it was while the valve was changed.
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Take the old valve out
The old valve came off with its lever arm and float. The footage shows the state it was in: the cover plate rusted through its paint.
The old valve after removal, its cover plate rusted through the paint. -
Fit the new valve
The replacement carries a product certification mark for sprinkler equipment, the approval insurers look for, and the WRAS mark, which means it is approved for connection to the public water supply. Both labels are on the cover and both are visible in the footage.
The new valve in place under the roof hatch, certification and WRAS labels on the cover. -
Prove it on the day
With the supply reinstated, the new valve opened and filled the tank, which is on the footage. That is the test that matters for an infill: that it opens when the level is down.
Watch it on film (0:07)
The result
A new, approved float valve on the sprinkler tank, and an infill proved working on the day.
- A new 3 inch float valve on the sprinkler tank, with its certification and WRAS marks on the cover
- The infill proved on the day: the new valve opened and filled the tank
- The tank’s stored water left in place while the valve was changed
Read next
- Sprinkler tank maintenance The water supply behind the system, inspected, cleaned and replaced when it is past it.
- Sprinkler tanks: inspection, cleaning and when to replace What a sprinkler tank owes under BS EN 12845: the weekly level check, the annual internal inspection, low level alarms, and when a tank is past repair.
- Sprinkler repairs: leaks, seized valves and damaged heads What actually breaks on a sprinkler system, why a leaking head must never be tightened, and what a repair involves when the system has to stay in service.
- Sprinkler and riser work in Kettering What we do in Kettering, Northamptonshire, and the buildings we work on there.
- All our work Every case study, and photographs from other jobs.
Questions about sprinkler tank float valve replacement
Does the sprinkler system have to be shut down to change a tank float valve?
No. The float valve only controls the refill. With the mains supply to it isolated, the tank stops topping up, but the water already stored stays in the tank and the system can still draw on it. On this job the refill was out of action only while the valve was being changed.
How long does it take to replace a sprinkler tank float valve?
A like-for-like change on a tank with safe access is a single visit. On this job an engineer and an assistant took the old valve out, fitted the new one and proved it filling the tank on the same day. Access decides most of it: a valve under a roof hatch needs the ladder and the hatch to be safe first.
What do the marks on a sprinkler float valve mean?
One is the product certification for sprinkler equipment, the approval insurers look for. The WRAS mark means it is approved for connection to the public water supply, which matters because the valve is fed from the mains. The valve fitted here carries both.
How often should a sprinkler tank float valve be checked?
Check the water level every week, and see the refill working at the annual tank inspection. Any time the level has been drawn down, by a test or a drain down, is a good moment to watch it recover: a valve that is slow to open, or that does not close, shows itself then.
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