If your boiler pressure gauge is showing low, or it keeps dropping after you top it up, that is usually a sign of a leak or fault somewhere in the system — not something to keep resetting yourself. Call 020 7183 4810 and we will find out why.
Boiler pressure keeps dropping?
We diagnose the cause and fix it properly, not just top up the gauge.
Need a Gas Safe engineer today?
Same day callouts across Central and West London, fixed quotes and fully guaranteed work.
What boiler pressure tells you
Most sealed heating systems run between 1 and 2 bar. A reading that is consistently low, or that drops again shortly after being topped up, means water is escaping the system somewhere — from a radiator valve, a pipe joint, the boiler itself, or the pressure relief valve.
Signs of a real underlying issue
- Pressure needs topping up more than once every few months
- You notice damp patches near pipework or under the boiler
- The boiler is locking out or displaying a fault code
- Radiators are not heating evenly alongside the pressure issue
Why we do not recommend repeatedly topping up yourself
| Common online advice | Why it falls short |
|---|---|
| “Just use the filling loop each time it drops” | This masks a leak instead of fixing it, and can cause damage if the loop is left open or used incorrectly. |
| “It is normal for pressure to drop a bit” | Small seasonal changes are normal; repeated or rapid drops are not and mean water is escaping somewhere. |
Stop and call us if…
- You are topping up pressure more than once a month
- You see any visible water leaks or damp patches
- Your boiler shows an error code alongside low pressure
- The boiler cuts out or will not fire at all
What it costs to wait
An unaddressed leak wastes water, can cause damage to floors, walls or ceilings, and puts unnecessary strain on the boiler, which can lead to a full breakdown. Catching it early is almost always cheaper than the repair bill after a component fails.
How Olia’s Plumbing & Heating handles it
- Call 020 7183 4810 and describe the pressure issue
- Our engineer traces the source of the pressure loss
- We repair the leak or faulty component
- We confirm the system holds pressure correctly before we leave
Get your pressure issue diagnosed properly
Fast, reliable call-outs across London.
Frequently asked questions
What is normal boiler pressure?
Typically between 1 and 2 bar when cold. Check your boiler’s manual for the exact ideal range for your model.
Why does my pressure keep dropping?
Usually a leak in the system, a faulty pressure relief valve, or an issue with the expansion vessel. This needs diagnosing rather than repeated topping up.
Is low boiler pressure dangerous?
It is not usually an immediate safety risk, but it can cause the boiler to stop working and points to a fault that will get worse if ignored.
Can I keep using the filling loop myself?
Occasional light use is common, but if you are doing it often, call us — that is a sign of an underlying problem.
Do not keep resetting the pressure and hoping it holds. Call 020 7183 4810 and we will find the real cause.
Related services: Boiler Repair Central London, What Causes Low Boiler Pressure, Boiler Service London
Peyman
CEO & Founder — Gas Safe Registered Engineer
Peyman is the founder of Olia's Plumbing & Heating, a London based team with over 15 years of hands on experience in boiler installation and repair, central heating, gas work and emergency plumbing. He personally oversees jobs across Central and West London and writes these guides to help homeowners understand their heating systems.
- Gas Safe Registered
- 15+ years experience
- Covering all of London
