How to increase water pressure in a shower with a combi boiler

Combi boiler shower pressure

Combination or ‘combi’ boilers are very popular in the UK, making up more than half of all new boilers fitted. These appliances are highly efficient central heating and hot water boilers combined in one space-saving unit - hence the name. They eliminate the need for a separate hot water cylinder, saving you space and giving you a hot water supply that is always available on demand.

The appliances heat water directly from the mains and deliver it to your taps and showers at mains pressure. So, if you have strong mains pressure in your home and you don’t have too many demands on your hot water, they can provide powerful showers without the need for a pump. However, if your mains pressure is low or you have multiple taps and showers running from your boiler, a combi model may struggle to deliver the results you want. You might find that the water flow is weak when other showers or taps are being used, or that your shower suddenly runs too cold or hot.

How to increase water pressure on a combi boiler

Because they are mains fed, you are limited in your options when it comes to increasing water pressure with a combi boiler - and you can’t use a pump directly from the mains supply to provide a boost. However, there are certain steps you can take. 

For example, you should make sure that the boiler you go for is powerful enough to supply a strong flow of water. Ideally, the combi boiler flow rate for a good shower should be at least 12 - 15 litres a minute. The flow rate simply refers to how much water can pass through the appliance to feed taps and showers once the boiler is working.

Choosing a powerful combi boiler with a good flow rate will help you to optimise hot water pressure around your home. It’s important to note however that you are restricted in terms of flow rate by the mains pressure delivered to your property. So, if you get a boiler with a maximum flow rate that exceeds your mains water supply, you could be wasting your money because the appliance won’t reach its full potential.

Knowing which appliance is right for your home isn’t always easy, so you may benefit from consulting a heating engineer.

Can you have an electric shower with a combi boiler?

Electric showers are supplied directly by cold water from the mains, so they can be used regardless of the type of boiler you have. Just like a kettle, electric showers use a heating element to get water to the desired temperature, and this water is then fed through the shower head. 

Electric showers aren’t renowned for being particularly powerful, but they do provide a reliable flow of water regardless of any other taps or showers that may be being used at the same time. They can therefore be a good option if you have a combi boiler and more than one bathroom.

When choosing one of these showers, consider its kilowatt rating. Generally speaking, the higher the rating, the stronger your water flow will be. Again though, this is contingent on the mains pressure delivered to your home being sufficient.

Can you have a power shower with a combi boiler?

In short, no you can’t. Power showers operate with an in-built pump that makes them incompatible with combi boilers, and they need to be connected to a hot water cylinder - which is a feature that combi boiler systems don’t have. So, if you want to have a power shower in your home, you’ll need to rethink your heating system.

Which is more cost effective - an electric shower or a power shower?

It is also worth noting that because the flow rate for electric showers is generally lower than alternatives, they are also often the most efficient in terms of energy consumption - especially compared to a power shower. This means that you may be able to save money by choosing to fit an electric shower.

Can you fit a shower pump to a combi boiler?

You can’t fit a shower pump to a combi boiler to increase water pressure. As mentioned previously, shower pumps are connected to hot water cylinders, and this is a feature that combi boiler heating systems lack.

Should you consider getting a different type of boiler?

There are myriad benefits associated with combi boilers. For example, the answer to the question ‘how long does a combi boiler take to heat water?’ is no time at all. These appliances provide hot water on demand, meaning you never have to plan ahead. However, if you have a combi boiler and you want to increase water pressure in your showers, you may wish to replace it with a different type of appliance.

Both conventional boilers and systems boilers can provide enough hot water to achieve good pressure in multiple taps and showers simultaneously, and they are compatible with power showers. A system boiler may be a more practical option if you’re switching from a combi design because it is easier to install than a conventional model, does not require a cold water storage tank in the loft and can provide hot water on demand.  

However, if your property can accommodate one, a conventional boiler may be a good option if you live in an area where the mains pressure is low. Bear in mind though that these systems do not provide instant hot water.  

You’ll need to program your thermostat to preheat water ready for you and your family to use.