DOMESTIC SPRINKLER SYSTEM info for end users/ householders

Domestic fire sprinkler systems are often required by Building Control or legislation, due to poor fire brigade access, building design and other factors, or simply families choosing to protect themselves from the devastating effects of fire.

We aim to give you a guide of of what to look out for to ensure if you need fire sprinklers, and  that they are installed to the rules (this is all a bit dull, but it is clear and written for anyone to understand- ignore it at your peril)


Each fire sprinkler is activated independantly in a fire usually at 68 degrees centigrade, your house will not become a Hollywood movie scene, the sprinkler system will react locally, one head at a time if they are required.


Town main system or pump and tank?

A domestic dwelling may be able to run off the town main water supply.

If the town main water is acceptable, an automatic priority demand valve will be needed to turn off the household water supply in the event of a fire.

If the water meter is in the road it could be difficult to utilise a town main system with sufficient flow/ pressure.

If your supply is old lead or less than 32mm it's highly unlikely a town main will be acceptable in most cases.

Town houses/ taller buildings will probably not have sufficient dynamic flow rate in the town main supply to run sprinklers at the higher levels in the building. Your contractor is responsible for testing the main prior to any work being carried out, to assess suitability.

At the comissioning stage your house must be on maximum water demand eg a shower and a toilet refilling, with the flow test being carried out. A priority demand valve must be fitted if it doesn't pass.

If it doesn't pass and a PDV is necessary, the test can be repeated with the domestic supply off. This will test if there is enough dynamic flow rate for only the sprinklers.

You will need a fused spur to provide power to the demand valve. The fitting of this valve is in your household supply so it may be your responsibility to fit the valve. A Grifen pdv will failsafe (close on power loss) so the circuit does not need power backup.

It is however imperative that any certificate offered by the installer has checked the operation at full demand and full sprinkler flow. 

Installers can not leave that upto you and they can't issue a certificate either, if it is not done.

Suction lift; Grifen offer pumps that can suck the water from an underground tank, this should generally be avoided as a tank with a positive pressure is preferred. If you have no space, it is an option to have a burried tank, it will add cost. Underground tanks are also category 5 fluids, so the water is in effect effluent.


If the town main water supply is not sufficient there are 2 options

1)Water storage tank and pump. The water tank will typically be 1200litres or over, if 2 sprinklers are in any one room.

The water supply must last for a minimum of 10 minutes. An infill to the tank is allowed, this can only account for 40% of the required capacity as a maximum. Infills must be proven with a flow test and the infill must have a type AB air gap (a cistern above the main tank) as required by water regulations.

A 10% factor of safety is required as a minimum.

Water tanks must have a low level alarm, although described as low level it should alarm at circa 90% full.

Sprinklers discharge more water at lower building levels (the most favourable area of operation), the tank and pump must be capable of meeting this demand.


Limit your tank size Grifen offer flow controlled pumps- BOOST8n domestic pump which limit your tank size. The calculations should be shown on the design drawings (you MUST be issued with these, please check for remote and favourable area calcs). There is an unscrupulous Nationwide company that will always lead you to believe your main is good enough, if your quote states that, then make sure you witness the flow test before committing, it's very easy to prove one way or another, don't leave it until work has started and then get told- "Oh sorry you need a pump and tank".

It will get suprisingly expensive very quickly and it is avoidable. You may need a tank, that's life, just make sure you know either way before you buy, then you can compare like for like quotes not apples with poison ivy. 


2) Pumping off the main. A dynamic flow test of +20% of maximum demand will need to be done and written permission from the water authority is required- it's the law! That could be as much/over 140litres / minute, you are only allowed to pump a maximum of 12 litres per minute without permission.

No fire sprinkler pump will ever meet this rule.

There is a WRAS approved system on the market, the water authority do not have jurisdicition over BS9251 2014 fire sprinklers, other than saying you can't fit a given pump.

An approval from WRAS does not in any way mean a sprinkler pump complies with BS9251 2014.

Domestic fire sprinkler pumps must meet rule. 5.3.3 for system flow rate.

You can't connect sprinkler pumps to household plugs, they have to have fire rated cables and once defined as a fire pump they can't stop. A pump can't be slowed down and meet rule 5.3.3 to try and compensate for a poor main.

If pumps are slowed they quite simply do not comply and you can't be issued a certificate of compliance!

If you do have a booster pump then sprinkler systems are classfied as class 2 fluids which means it's no longer potable/drinkable, so you need WRAS approved back flow prevention and permission from your water provider. Most sprinkler components are not WRAS approved for this reason as it is pointless. In the case of a booster pump you will almost certainly need a priority demand valve fitted into your household supply, that valve does need to be WRAS approved as it is in the potable supply.

Once again any certificate offered MUST have your house on full demand and the sprinkler pump on demand.

It is the responsibility of the contractor to ensure the priority demand valve closes.

Monthly pump test Grifen pumps do weekly tests as we think it's safer, we also drop the pressure to ensure the pump works in real life conditions. Some systems test pump current, BS9251 2014 does not mention the words; current, amps or motor.

Pumps that only test motor current are dangerous and don't comply with the standard!

You may be surprised which manufacturers use this cheap trick- ask for clarification in writing!

A pump that tests motor current could be cavitating and be ineffective in a fire, in engineering terms a false positive.

It may be cheaper, but you are paying for it anyway, insist on it being done properly.

Grifen comprehensive testing has found systems with a mistakenly closed tank valve, our weekly test failed for good reason, the system was not operative.

The failed test caused the occupier to find the cause and remedy it, making it safe!

With the benefit of our LCD screen a site visit wasn't required- simply a friendly phone call.

Certificates issued with pumps that test motor current are invalid!

See rule 5.9.3 and Tems and Definitions 3.22 Pump;"automatically operated device that provides water to a sprinkler system".

Keep compliant and specify a Grifen pump, ours 100% comply with all rules and we're happy to explain how.


You will need to employ a fire sprinkler contractor, commercial companies carrying LPCB approval have a knowledge base way beyond that required by BS9251.

They will be able to install residential systems as well as domestic and residential companies.

Remember when entering into any commercial agreement it is important to do some due diligence- check the contractor and the directors of the companies previous history, this is very easy to do for free at a basic level on the internet and may save you a big problem.

Photographs of previous installs should help you, pictures of completed houses tell you nothing of what you should expect.


Technical drawings and flow calculations (rule 5.7) will be carried out by the contractor to BS9251 2014

Basic maths principle

Domestic fire sprinklers require at least 1/2 bar of pressure to operate.

Building height also adds to the pressure required, each storey being circa 3 metres adds 0.3 bars.

Pipe work friction then adds losses, which must be compensated for.


So for a three storey building you could expect;

0.5bars (sprinkler minimum operating pressure)

+ 0.3 (pressure in bars /floor) x 3 (floors) =0.9 bars 

1.0 bar (frictional loss created by the pipe system itself-varies with pipe size and system complexity)

= 2.4 bars (similar to your car tyre pressure)  at around 100litres per minute.


A flow test will need to be carried out on completion, it is worth witness testing this, you will be given a certificate as evidence.

A test valve will be opened and the flow meter should read the required flow e.g 100litres/ minute, the gauge should read the required pressure during the flow test. e.g 100litres/ minute at 2.4 bars.

BS9251 2014 test methodology diagram is incorrect, it is imperative a valve opens the flow line, then a long length of pipe, then a flow meter, another long length of pipe and then a throttling valve, as per the International standard EN12845.


This is a simple guide and your fire sprinkler contractor should be able to answer questions specific to your home.

You must be provided with drawings of the system and the name of the installing contractor must be prominently displayed, a cabinet/ spares should be provided.

If any of these are not being provided you should seek further advice.

Power cables to your pump system must be fire rated as should alarm cables, they are usually red or armoured.

It is essential you see this system working and what happens if something has failed or there is a fire.

There are plenty of people who die in fires, make sure your system works, you wouldn't buy a televison with a remote control that doesn't work.

Why buy a sprinkler system that is not complete/ functional.


Each year you will be required to carry out a service, similar to a landlord gas check which will involve a sprinkler head check, flow test etc.

A Service requires a walk round survey of the site according to BS9251 2104, systems which dispense with annual visits do not comply with BS9251, however rigorous a remote test is claimed to be! There is even an LPCB approved annual flow switch test device, that's all well and good, but it's marketed as not needing a visit- that is against the rules. It is very clear the risk needs to be checked and a functional flow test carried out, testing a flow swith is not the same.

Certificates must clearly state if non compliances / deviations from BS9251 2014 have been used.  Contractors may put electrical/ alarm/ heating services at the risk of the customer, please ensure if pumps are installed outside/ in lofts, that you either protect them from frost or it is done as part of the system. BS9251 2014 now puts the onus on the sprinkler contractor and all the alarms and fault alarms must be tested by the contractor, telling you that it's "by others" is no longer acceptable! You must never accept it.

You may have to do the work as it is your property, but you can NEVER get a certificate until it is all complete. If you are a landlord your insurance will probably be invalid, if there is a loss, it is totally avoidable so please follow our basic guide.

We have made  a simple precis of BS9251 2014 and put in laymans terms so you can follow it/ question it and act on it and be safe and insured.


Partial sprinkler systems do not comply with BS9251 2014!! even if an Authority having jurisdiction allows them (but they don't comply- never, your certificate can't state that it does).

Anyone that will issue a certificate is lying, after all cars have more than one seatbelt, remember fires do spread, as does smoke.

The whole house should be protected and has to be to comply.

If you are being offered partial protection without a fire officer or builiding control officer stating it is acceptable- walk away!

If you get a complaince certificate, question it.

Non compliances are allowed on certificates, but they must be stated. Remember amazing prices may may be amazing for a reason, ultimately if something is wrong with the amazing low price system it may be you carrying the can later, it is easy to do simple checks.

The majority of installers will provide excellent systems.

If you are offered a town main system, make sure you are fully aware of the total cost of installing a pump and tank if it is required, after the flow test failing, being tied to a contract then having a pump and tank added without knowing the implication could be a bank breaker.


Remote test valve (Terms and definitions 3.3 Alarm test valve)  must be fitted at the most remote area of the sprinkler array, to ensure opration at the highest level.

This valve is also used to vent air, make sure one is fitted, spraying compressed air at a fire will lead to disaster, it's in the rules.

Many pipe systems won't tolerate compressed air, so you have to vent it.

As the system is filled with water the trapped air gets compressed at the top of the building.


We hope this information will help you install a fire sprinkler system and ensure it is done well.

Of course cost is a consideration but it must be done correctly and that may mean paying a little more.

Domestic sprinkler systems are designed to allow for property escape but they also by their nature protect your valuables and more importantly the family memories.

Fire and fault alarms will form part of the fire sprinkler system.

If a pump is fitted it must be monitored for power failed and weekly test failed.

The alarm must be visible or audible at an obvious location in the house, an audible alarm on a pump probably doesn't comply, unless you put it in your front room.

A simple fire alarm panel is the easiest way to achieve compliance.

If you have a pump and you ask for it to be switched off, a fault alarm must be seen or heard.

A fire alarm should be raised if there is flow in the sprinkler system (this may take upto 30 seconds to trigger to prevent false alarms). 


It is good to make a plan for escape and teach any children what they should do if they hear the alarm.

Fire alarms and pump cables must be fire rated, of course as you browse our website you'll see the red Fire rated approved cables everywhere.

Power connection

It is common to connect pumps to the incoming electric supply directly after the meter.
Pumps must not be protected by RCD's or other trip devices protecting other household circuits which may turn off the fire pump.
The first thing the fire brigade will try and do is cut the main supply, if your power comes from before that, the sprinkler pump stays on.
They must now be fused, MCBs are not accpetable (don't know why, it's just a rule).
Pumps must have a local means of isolation by a rotary isolator not a fused spur!

Machinery Equipment directive

This is law and applies to all motor driven devices, ie your sprinkler pump.

The pump is designed to run until destruction when defined as a fire pump unless switched off.

This is a runaway condition and could cause superheated steam which is dangerous.

Some pump systems don't have this feature, if they don't they don't comply with the directive, unless a relief valve is fitted.

Grifen sprinkler solutions pumps have auto cooling as standard and with our larger pumps, we've added intelligent interactive cooling too.

Many of our pumps have been saved in accidental starts, we replace many of our competitor pumps that have burnt out due to overheating.  


We can of course provide products that comply for all the above, however if your contractor choses to go elsewhere that's no problem for us, just make sure they follow the logic, because that's what the standard says.


You can't get a retrospective certificate from the undertaker, nor will your insurance pay out with a wonky certificate.


Please call us if you have a question.