shower pumps buying guide

Shower Pumps: Guide to Buying and Fitting

Many homes suffer from low water pressure which can influence the shower you can install in your bathroom. But what can you do to ensure a faster running and more enjoyable shower?

You’ll need a shower pump. If you have a low-pressure system, you’ll know what it looks like - poor flow from your taps, a slow-filling bath and a weak shower. If you like the ease and practicality of a shower, low water pressure can put an end to that.

So, what are shower pumps? Plumbworld is here to explain everything there is about them, including what they are, how they work, buying tips and the installation process.

Read on to find out more about shower pumps before you buy…

What is a shower pump?

what is a shower pump?

A shower pump is a small device that boosts water pressure in your pipes by increasing the volume of water which is pumped through them. The improved water pressure is visible at the showerhead where the force of the spray increases as the pressure and flow rate become stronger.

How do I know if I need a shower pump?

It’s likely that you have already identified the need for a pump, as your water pressure is low. However, there is a simple way to test your shower’s flow rate, following the steps below.

Read more: What Are The Different Types of Showers?

How to check your water pressure

You can check the water pressure of your home yourself by measuring the distance or drop between your water tank and the tap in metres.

An easy way to remember is this: One metre = 0.1 bar

How can I test my water pressure?

How do i test my water pressure?

To test the water pressure in your taps, get yourself a water jug between one and two litres in size and a stopwatch. Put the jug under a tap, turn it on, and time six seconds. Then, turn your tap off.

Now, the following calculation:

The amount of water in the jug in litres multiplied by 10. 

The resulting figure will be your property’s flow rate in litres per minute. If the flow rate is less than 10 litres per minute, you have low water pressure. A flow rate between 10 and 15 litres per minute is considered acceptable but can be improved. A flow rate that is above 15 litres per minute will be regarded as good.

How to test water pressure for a shower

Like testing your water pressure, you’ll need a one-litre measuring jug and a stopwatch. Place your jug under the shower and turn it on. Then, time how long it takes to fill the jug. If it takes longer than six seconds to fill the jug, your shower is running at a low water pressure.

What are the types of shower pumps?

When deciding on a shower pump you'll need to look at a range of options. It can all get a bit confusing if you think it’s as easy as just picking one and going with it. First of all, you'll need to choose whether you want a single or twin shower pump.

What to consider when buying a shower pump

Deciding on the right pump for your shower system doesn't have to be as complicated as you'd think. That being said, many people opt to have a professional in to sort it out. However, if you’re looking to source a specific pump or do all the work yourself then you’ll want to bear the following things in mind before purchasing:

Position & Installation

Most people opt to fit their shower pump in the airing cupboard or near your water tank so it will most likely be out of sight. To reduce noise levels, you can install a vibration mat which limits the number of vibrations therefore keeping noise to a minimum.

Which shower pump do I need?

Understanding shower pumps and the different terms is certainly important. The difference between single and twin impeller as well as whether you need a positive or negative head all needs to be addressed:

Single or Twin Impeller?

An impeller is another word for a pump, just to clear up any confusion. 

  • Single Impeller: A single shower pump. These impellers can only pump one type of water feed; hot, cold or sometimes mixed. This is used in most cases to pump water to the mixer which already has a cold mains supply.
  • Twin Impeller: A twin shower pump. These, on the other hand, can pump both hot and cold water straight to the mixer resulting in an equal flow. This makes them much more desirable and therefore the most popular option.

Once you've decided between single and twin pumps, you'll need to choose whether you need a positive or negative head shower pump.

Positive or Negative?

We’d recommend finding this information out from a registered installer to be sure.

  • Positive Head: There needs to be a ‘head’ of 500mm between the top of the showerhead and the base of the cistern to ensure a gravity flow of 0.6L a minute. This is suitable for a positive head pump as the water is pushed through.
  • Negative Head: If the pump is going to be installed on the same level or above the cold water tank, a negative head type of pump is required since it sucks water from the tanks.

How to fit a shower pump

Important: Before starting this job, you must switch off the electricity supply. You should also turn off your water supply.

Read more: How to Install a Shower

When you’re planning where to place the shower 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.

To be absolutely safe, you must ensure that the pump is not covered or at risk of being covered. If this happens, then the motor could overheat and cause serious damage to the pump. This is important if you plan on having the shower pump inside an airing cupboard.

Tip: Likewise, the shower pump must never be exposed to very low temperatures, so make sure that the location you’re planning to site it in is always guaranteed to be frost-free.

Never ignore regulations when it comes to installing any electrical product. To comply with wiring regulations, an enclosed shower pump must be sited at least 2ft (600mm) away from the shower tray or basin.

The pump can be connected to your electrical supply from a 230v switched spur off a ring main. It should never be connected to the supply for the hot water cylinder immersion heater or any other high-load installation that needs a dedicated supply.

If you’re concerned about noise, you can reduce this by setting the pump on a small concrete foundation, about 2ins (50mm) thick. Never screw your shower pump to the floor.

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. 

Tip: the pump should be supplied through 22mm pipework regardless of whether it has 22mm or 15mm connections.

To prevent air from 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.

Note: A flange is a device that limits the amount of air entering a pump from the hot water cylinder. Flanges are crucial in ensuring the longevity and quiet running for the pump.

Always make sure that 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.

Tip: Make sure that the pipework is thoroughly flushed before connecting the pump. This will help prevent debris from entering the pump and damaging it.

Once installed, the shower pump and the pipework should be primed. Do this by - with the electrical supply already off - running a bucket of water out of both the hot and cold sides until it runs clear. This will prevent air from becoming trapped in the pump.

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