Water Pressure & Combi Boilers

Water Pressure & Combi Boilers

Water pressure and the flow of water from your taps

One of the regular concerns of prospective combi boiler customers is the flow of water from appliances.

The flow and pressure of water into your home from the mains is something you cannot alter, but many people with combi boilers do not understand how this can affect their use of various outlets.

It is a fairly common complaint that when someone is using the shower, the water flow drops and usually that is because someone else in the house has turned on taps, perhaps in the kitchen to do the washing up.

This can be noticeable in homes with a combi boiler because these boilers run on cold water supplies only, which are then heated up when a tap, shower or the central heating is turned on and the boiler fires up.

So, you cannot improve things by installing a shower pump as these only work if you have a gravity fed water system (usually with a tank in the roof space).

Water pressure is the measure of force to get water through the mains and into your pipework. It is measured in “bars”—one bar being the equivalent to the force required to push water up to the height of 10 metres.

Water pressure can vary greatly from home to home, room to room and even at different times of the day.

It can also vary due to the demand, so that, for example, between 7 and 9am you may experience lower water pressure as other people in your area also use water for baths and showers.

There is not a great deal you can do to improve things, but you should get your Gas Fitter/Plumber to ensure that your stop tap is fully open and any systems are set to the statutory minimum level of 1 bar.

According to OFWAT, the national water regulator, other causes of low pressure can include:

  • inadequate pumping facilities
  • water mains that are too small
  • reduced pressure from the water main as a result of leakage, equipment failures or blocked service pipes

These are all the responsibility of your water supplier and if you are having consistent problems with low pressure it may be worth contacting them and getting them to check on the supply.

Inside your home, it may be worth checking that there is no problem with the plumbing, such as leaks or air bubbles in the radiators.


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