Covid-19 Update - We are open for business and continuing to repair, service and instal boilers for our customers. When an engineer does visit a customer’s home, they’ll take additional precautions – including hand-washing – before, during and after the appointment. Our engineers will arrive in PPE so that they're protected too.

Our staff have been categorised as key workers, so they can still visit your property during this time.

What to do if your boiler has low or high pressure

What to do if your boiler has low or high pressure

Boiler pressure

If your boiler is losing pressure, it is likely resulting in other problems too such as no hot water.

How can I check my boiler pressure?

Checking your boiler pressure, it usually pretty easy, as on the front of the boiler you will find a water pressure gauge. The needle on this gauge will show the water pressure. Water pressure varies from model to model, so you should consult your manual but as a guide, a low pressure is less than 1 bar, high pressure is above 2.75 bar and somewhere in the middle is normal (when your radiators are cold this is usually just above 1 and when they are hot it is normally just above 2). Some digital gauges will even flash with a pressure warning if you have high or low pressure.

If you have high or low pressure, then your boiler will not be operating efficiently and could even end up damaging your home, so it is important to fix. Never open the boiler itself unless you are an expert as this can be dangerous.


Why do I need a constant pressure?

A boiler heats cold water to make it hot and this flows through pipes to give you hot water for instance in the shower and this water also flows through your radiators to heat your home. For the system to work efficiently, the pressure needs to be stable, if it is too low, it won’t be able to circulate the water which is why you often then get cold water or cold radiators.


What causes a drop-in pressure?

A drop-in pressure is usually caused by water exiting the system. There are two common causes for this- bleeding radiators or a leak. Take a look around your home and see if you can find any wet patches or drips near your pipes to see if you have a leak. If you have a leak, you will need to fix this.

A drop-in pressure could also be caused by an internal problem within the boiler – only a trained engineer should open the actual boiler.


What causes my pressure to be too high?

When a boiler has too higher pressure, it is often a sign that radiators need bleeding. If some of your radiators aren’t heating up, these will be the radiators to bleed as it means they have got air in them.

If bleeding your radiators doesn’t bring your boiler pressure down, then make sure you get it checked by a professional.


How can I fix the boiler pressure?

Boiler systems vary depending on the brand and model, so it is always best to check your manual, or if you have any doubt, you can always call us out as we have Gas Safety engineer who are experts at this.

To increase the boiler pressure, you have to add water from the mains water supply via the filling in loop. If you have any doubts on how to do this, we would recommend you have one of our engineers come out and do it for you.

To decrease the boiler pressure, try bleeding a radiator.