Topping up means allowing more water into the central heating system. You may need to do this if you have had a leak in the boiler, pipework or radiators. If the system is working properly, you should only have to increase the boiler pressure once or twice a year.
Can you top up a boiler when it is on?
To top up a boiler with fresh water and increase pressure, you should not top it up when it is on. This is because it won’t give you an accurate system pressure reading and you could end up not putting enough water in, or too much. It’s important to turn off the boiler and let the heating system cool down before you top-up.
In most modern combination boilers, the water pressure is maintained by the filling loop which can be either externally or internally connected to the cold water mains.
What pressure should my boiler be?
When the heating is on, the pressure can be anywhere between 1 and 2.5 bar. Your boiler user manual will tell you what the ideal pressure is. With the boiler off, the pressure will be lower than when it’s on, between 0.75 and 1.5 is normal.
Do I need to turn my boiler off to top it up?
It is not necessary to turn the boiler off to repressurise the system. You won’t have to switch off the power to it either. You will need to turn off the central heating, which can be done from the room thermostat, and let the system cool before filling it with more water.
When to check the boiler pressure
- When the boiler won’t start up.
- After bleeding a radiator.
- If you have any cold radiators.
- Before turning on the heating after a long time.
- Once a month during regular use.
What to do if the boiler regularly needs topping up
Having to regularly top up the boiler usually means there is a water leak somewhere in the system or the water pressure gauge may show reduced system pressure after bleeding a radiator.
You will need to investigate around the house for damp patches or leaks around radiators or check if drops of water are leaking down from the boiler itself. You may need to call in a gas engineer to fix the problem properly.
If you won’t be able to make an unexpected expense such as a boiler repair, you could look to getting a repair plan from Hometree who offer customers peace of mind with home cover packages for their boiler, central heating, plumbing, drains and home electrics all at an affordable monthly or annual cost. Click the link below to find out how you can save
Do I need to top up my boiler every day?
It is not normal to top up a boiler every day, even if you have a small leak somewhere in the system. You should call a gas engineer to investigate as this could be a fault within the boiler.
Topping up the boiler once or twice a year is normal. We hope you have found this quick guide helpful but if you are not comfortable dealing with this type of boiler issue then please call a local gas engineer. Check out Boiler Guide on the link below to find local engineers.
*The information in this article should be used for general guidance only and not as financial or health advice. Full details are on the link in the footer to our disclaimer page. Always discuss your requirements with a competent and suitably qualified professional before undertaking any work.
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