What should the pressure be?
On most combi and system boilers the pressure gauge should read around 1 to 1.5 bar when the heating is cold. It rises a little when the boiler is hot. If it is below 1 bar the boiler may stop working, and if it is much above 2.5 to 3 bar something is wrong and the pressure relief valve may start to drip.
Why does boiler pressure drop?
- A leak somewhere in the heating system, from a radiator valve, pipe joint or the boiler itself.
- Bleeding radiators, which lets a little water out of the system.
- A faulty pressure relief valve or expansion vessel losing its charge.
- Air in the system.
How to top it up
Most boilers have a filling loop under the boiler. With the boiler off and cool, open the filling loop slowly until the gauge reads between 1 and 1.5 bar, then close it fully. Check your boiler's manual first, because the method varies.
When to call an engineer
If the pressure keeps dropping after you top it up, there is a leak or a faulty part and it needs a Gas Safe registered engineer. Do not keep topping it up, because that hides the problem and can damage the boiler.
Need an engineer?
If you are near Newcastle-under-Lyme, call or message and you speak to the engineer who does the work. A clear price is given before anything starts.
Boiler repair in Newcastle-under-Lyme
More guides
- Boiler showing error code F1: what it means
- How often should a boiler be serviced?
- Landlord gas safety certificate (CP12): what you must do
- Combi, system or regular boiler: which is right?
- Signs you need a new boiler
- Why is my boiler making a noise?
- Radiators cold at the top or the bottom: what it means
- Carbon monoxide and gas safety at home
- Frozen condensate pipe: boiler stopped in cold weather