Posted on Thursday 30th May 2019
Installing a shower pump is probably the most common way people improve the performance of their showers. If you’re tired of standing under a weak flow of water from your shower head, then consider installing a shower pump.
Keep on reading to find out everything you need to know about shower pumps and how to install them.
What is a shower pump?
Shower pumps are becoming increasingly popular. They are typically installed on systems where the head pressure is not sufficient to create an enjoyable showering experience.
In a traditional shower set up, water is fed into a hose (or into the unit first to be heated if you have an electric shower) and then travels up towards the shower head and out to shower you.
In travelling up the hose towards the shower head, the water has to fight against gravity - it does this using water pressure. With the water under pressure, it is able to travel upwards against gravity.
The amount of water pressure (measured in bars) required to get the water up to the shower head depends on how far the water has to travel. If you don’t have sufficient water pressure, then you’re likely to end up with a trickle of water coming out of your shower head. Not ideal.
The solution is a shower pump. Typically small in size (around 30cm on average), shower pumps boost the water pressure in your shower pipes by increasing the volume of water which is pumped into them.
How do I know if I require a shower pump?
There are few different things you can do to measure your water pressure. One of the easiest ways is as follows:
- Ensure all of you taps are turned off (as well as any appliances that use water such as dishwashers).
- Get a 1 litre measuring jug.
- Turn on your cold tap fully and fill to the 1 litre line of your jug whilst timing it.
Make a note of the time and then use this calculation:
60 / (time) = (x) litres per minute.
That means that if it took 7.5 seconds for your jug to fill up you just need to work out 60 divided by 7.5 to get 8 litres per minute.
The general rule tends to be that if it takes longer than 8 seconds to fill a one litre jug, then your water pressure is too low and as such, you’ll benefit from a shower pump!
What types of shower pumps are there?
If you’ve found that you need a shower pump, you might be wondering what type you require. If that’s the case, keep reading…
In most cases your choice will be between a positive shower pump and a negative shower pump. Which one is right for you will depend on what type of water system you have in your home.
Positive shower pump
Positive shower pumps are designed to be fed by gravity. To work properly, this type of pump requires a distance (also known as a ‘head’) of at least 10 inches between the water level in the cold water tank (usually located in the loft) and the pump. This will ensure that you achieve the 0.5 litres per minute flow that is required to activate most positive shower pumps.
If you are going to install a positive shower pump, you should also check your cold water tank. It should have a capacity of at least 225 litres (50 gallons) capacity to maintain supply to the hot water cylinder and the shower pump.
Negative shower pump
Less common are negative shower pumps. A negative pump is normally used in situations where the pump will be located either level with or above the cold water tank, for example, in bungalows where there isn’t enough distance between the tank and the pump.
Negative shower pumps work by actively ‘sucking’ water from the cold water tank to feed the shower.
For both of these types of pumps, you will need an open-vented hot and cold water supply. So, you won’t be able to use these types of pumps with a combi boiler system where there’s no stored hot water.
Another thing to consider is the number of impellers you’ll require. An impeller is a rotor which is used to increase the pressure and flow of water through the pump. You can buy shower pumps that are fitted with either single or twin impellers.
A single impeller pump is normally used to pump the hot water side of a water supply, whilst the cold water side of the supply is fed by mains pressure.
If the cold and hot water tanks are widely separated, then a single impeller pump will be required on each feed.
A twin impeller pump is designed to pump both hot and cold water. These are mostly used on positive head systems and produce an even pressure from both sides of the supply. They also have the benefit of delivering a more controlled mixing ability (so you’ll be able to adjust the temperature of your shower with more accuracy).
Regenerative or centrifugal shower pump?
Something else to consider is whether you want a regenerative or centrifugal pump.
A centrifugal pump moves water using a set of curved vanes. These vanes rotate, building up centrifugal force to force the water out, increasing water pressure. Centrifugal pumps are extremely efficient and are often quieter than other pumps. Where higher water pressures are needed, multiple impellers can be added to a centrifugal pump. Centrifugal pumps that have more than one impeller are sometimes called multistage centrifugal pumps.
Regenerative pumps (sometimes also known as peripheral or turbine pumps), gather water in a peripheral channel, building discharge pressure as the water flows in this channel around the circumference of the pump. Regenerative pumps tend to be cheaper to buy than centrifugal pumps.
Which bar shower pump?
When browsing our selection of shower pumps, you may notice that they each have a pressure rating. When purchasing a shower pump you should ensure you select the correct pressure rating for your shower set up.
Here are some of the most common pressure ratings for shower pumps:
- 1 bar shower pumps - this pressure rating is great for smaller shower heads where there won’t be a huge flow of water expelled.
- 1.5 bar shower pumps - this pressure should be used if you have a normal shower and just require a bit more water pressure.
- 2 bar shower pumps - like 1.5 bar shower pumps, a 2 bar shower pump is to be used if you have a normal shower set up that needs more water pressure.
- 2.5 bar shower pumps - if you want a power shower or have a larger than average shower head then a 2 bar shower pump will be required.
- 3 bar shower pumps - a 3 bar shower pump is great for power showers and larger shower heads. The extra water pressure these pumps create means they are ideal for showers that incorporate body jets.
Whilst those are the most common pump pressure ratings, you can also find other bar sizes on our store.
How to fit a shower pump
Once you’ve decided upon the right pump for your shower and water system set-up, it’s time to install it.
When deciding where to locate the pump, position it where it can be easily accessed once it’s installed. This will make it much easier to service it or clean the filters at a later date. If you have a bath, it’s permissible to install the pump underneath - however, you must be able to get quick access to the pump if necessary.
Shower pump safety
For maximum safety, ensure that the pump is not positioned in a confined space where it could overheat. This is particularly important if you’re thinking of installing the pump in an airing cupboard or similar location where it could be smothered by towels etc.
At the other end of the spectrum, pumps can also be damaged by very low temperatures, so you’ll have to factor this into your decision when positioning the pump.
While on the subject of safety, never ignore regulations when installing an electrical product such as a shower pump. To comply with wiring regulations, an enclosed shower pump must be sited at least 2ft (600mm) away from the shower tray or basin.
Your shower pump can be connected to your house’s electrical supply from a 230v switched spur off a ring main. It should never be connected to the supply for the hot water immersion heater or any other high-load installation that needs a dedicated supply.
Noise reduction for shower pumps
Sometimes shower pumps can be slightly noisier than people expect. If you’re concerned about noise, you should site the pump on a small concrete foundation about 2 inches (50mm) thick. This will dampen noise associated with vibration. Alternatively, placing the pump on a concrete building block will do the same job. Never screw your shower pump to the floor.
Shower pump water supply
You should always be able to isolate the water supply both to and from the pump. Fit a 22mm full bore isolating valve to the cold water pipe that supplies the pump. Pipework should generally be 22mm to reduce flow resistance to and from the pump. Furthermore, best practice dictates that the pump should be supplied through 22mm pipework irrespective of whether it has 22mm or 15mm connections.
To prevent air entering the pump, you should have a Surrey flange fitted to the top of the hot water cylinder if the pump has 15mm connections. An Essex flange should be used with pumps with 22mm connections.
Always make sure you use the flexible hoses supplied with your shower pump to link to both the incoming supply and the outgoing delivery pipes. Flexible hoses are less prone to vibration from the pump and should help reduce noise and prevent damage to the pump itself.
Make sure that pipework is thoroughly flushed prior to connecting the pump. This will help prevent debris entering the pump and impairing its operation.
Priming your shower pump for operation
Once installed, the shower pump and the pipework should be primed. Do this by switching the electrical supply off and running a bucket of water out of both the hot and cold sides until it runs clear. This will prevent air becoming trapped in the pump once it is commissioned.
To continue looking after your shower pump, you should read our article on shower pump care and maintenance. We’ve also covered some common questions about shower pumps that you may have.
Ollie is a self-trained DIY expert who particularly enjoys kitchen and bathroom renovations. In his spare time, Ollie enjoys cycling and hiking.
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- Step 1: Electrically isolate your pump. ...
- Step 2: Remove the electric wires from your shower pump. ...
- Step 3: Turn off the hot and cold-water supply. ...
- Step 4: Remove the water connection and the old pump. ...
- Step 5: Install your new shower pump. ...
- Step 6: Plumb your new shower pump.
Positive shower pumps are designed to be fed by gravity. To work properly, this type of pump requires a distance (also known as a 'head') of at least 10 inches between the water level in the cold water tank (usually located in the loft) and the pump.
A single shower pump can only be installed into a single supply, be it – premixed (see diagram), hot or cold supply. These days single shower pumps are mainly used to boost the hot supply if the cold is mains fed or if due to location it is easier to install two single shower pumps rather than one twin shower pump.
With low input pressure, the pump will be more prone to cavitation. That's bad for the mechanics and a waste of energy. Therefore, put the pump at the bottom, not the top.
If the shower is more than 600mm, about two rulers, below the cold water tank, then you need a positive head shower pump. If the shower is less than 600mm below the cold water tank, then you need a negative head shower pump.
A shower pump should be sited as close to the hot water cylinder as possible. However, if the shower pump is fitted in the loft or above the hot water cylinder (minimum static head required), regenerative pumps are a better choice as they tend to be less affected by the air that can accumulate in the system.
A shower pump must be connected to a system that is gravity fed. This is where the water is fed to the pump via a tank or cistern. These are often located in the attic of a house. An unvented system heats hot water at mains pressure, in this case, it is illegal to install a shower pump on your system.