Boiler Pressure: A Complete Guide for Homeowners in Tunbridge Wells, Crowborough, Uckfield, Rotherfield & Mark Cross
Understanding how your boiler works isn’t always easy. With various components to consider, it’s easy to overlook something as important as boiler pressure.
In this guide, we’ll walk you through everything you need to know about boiler pressure so you can spot potential problems early — whether you live in Tunbridge Wells, Crowborough, Uckfield, Rotherfield, or Mark Cross. It’s especially important for homeowners and landlords to keep an eye on boiler pressure to ensure the central heating system runs smoothly, delivering hot water to taps, radiators, and underfloor heating exactly when needed.
What Is Boiler Pressure?
Boiler pressure refers to the pressure of the water circulating in your boiler and heating system. You can check your boiler pressure using the pressure gauge — a small dial usually found on the front of the boiler.
This gauge helps you quickly spot if the pressure is too high (risking system overload) or too low (causing heating or hot water issues), both of which are common problems we help solve in homes across Tunbridge Wells and nearby towns.
Why Is Boiler Pressure Important?
Boiler pressure directly affects the performance and efficiency of your entire central heating system. If the pressure is incorrect, your boiler may stop working or perform poorly — something we see often in older systems in Crowborough or Uckfield homes.
Let’s break it down.
High Boiler Pressure
As your boiler heats water, pressure naturally increases slightly. However, it should remain within a safe range. If the pressure goes too high, it can cause serious problems — especially in properties with older pipework like those in Rotherfield or Mark Cross.
Signs your boiler pressure is too high:
The pressure gauge needle is in the red zone
Your central heating system has shut down
Filling valves are open or not properly secured
Water is leaking from the safety discharge pipe outside
Why is your boiler pressure high?
Your heating system needs a careful balance of air, water, and space for expansion. If there’s not enough air in the expansion vessel, pressure can rise too high.
Common causes of high pressure include:
Repressurising too recently without allowing pressure to settle
Faulty parts causing overpressure
Overfilled water system
Boiler age — especially if it’s over 10 years old
Note: High pressure can be dangerous. If you’re in any doubt, contact a Gas Safe engineer in Tunbridge Wells or surrounding areas for peace of mind.
How to Fix High Boiler Pressure
To reduce boiler pressure safely:
1. Turn off your boiler and allow it to cool.
2. Check that all filling loop valves are securely closed.
3. Bleed your radiators to release some water and reduce pressure.
4. Monitor the pressure gauge as you go — aim for 1 to 1.5 bar.
After bleeding, your system should stabilise. Keep an eye on it over the next few weeks. If the pressure rises again, it may point to a deeper issue — we recommend contacting Absolute Plumbing & Heating for professional boiler repairs in Uckfield, Crowborough or Tunbridge Wells.
Low Boiler Pressure
At the other end of the scale is low pressure. While not as dangerous as high pressure, it can lead to cold radiators, no hot water, and poor energy efficiency — not ideal in the colder months across East Sussex and West Kent.
Signs your boiler pressure is too low:
No hot water from taps
Radiators not heating
Pressure gauge has dropped significantly
Why is your boiler pressure low?
Common causes include:
Air escaping during radiator bleeding
A leak in the system (often around radiator valves or pipework)
An open valve somewhere in the system
If you’re in Mark Cross or Rotherfield and notice your radiators are slow to warm up, this could be the culprit.
How to Fix Low Boiler Pressure
Here’s how to increase pressure:
1. Turn the boiler off completely and let it cool.
2. Locate the filling loop (usually under the boiler with a braided hose and two valves).
3. Open the valves to allow water in and watch the gauge rise.
4. Stop when it reaches 1–1.5 bar and close both valves securely.
5. Let the boiler run for a few hours, then check if the pressure holds.
If pressure keeps dropping or you notice damp patches around your radiators or pipes, contact a Gas Safe engineer near you. We cover Crowborough, Tunbridge Wells, and all surrounding villages.
Does Your Boiler Pressure Keep Dropping?
You're not alone — this is one of the most common issues we deal with.
If your boiler pressure keeps falling below the recommended level, our team at Absolute Plumbing & Heating can help. We’ve fixed this exact issue in countless homes across Uckfield, Rotherfield, Mark Cross, and beyond.
Boiler Pressure by Type: Combi, System & Standard Boilers
Your boiler type can also affect how pressure should be monitored and managed.
What Pressure Should a Combi Boiler Be?
A combi boiler should have a pressure between 1 and 1.5 bar. Below 1 bar? You may need to repressurise or call an engineer to check for a leak or system fault.
We often help homeowners in Crowborough and Uckfield who’ve recently bled their radiators and are unsure how to rebalance their pressure.
What Pressure Should a Standard Boiler Be?
Standard (heat-only) boilers often don’t have a pressure gauge because they use a tank in the loft. However, if your system has a separate expansion vessel (a large red tank), it likely has a gauge that should also sit around 1–1.5 bar.
These setups are more common in older homes across Rotherfield and Mark Cross.
What Pressure Should a System Boiler Be?
System boilers work similarly to combi boilers in that they have built-in pressure monitoring.
The correct range is still 1–1.5 bar, and many modern boilers have digital pressure readouts. It’s useful to check the pressure both before and after switching the boiler on to see if it rises too quickly.
Need Help With Your Boiler Pressure?
If you're in Tunbridge Wells, Crowborough, Uckfield, Rotherfield, or Mark Cross, and you're unsure about your boiler pressure — or it keeps dropping — let us take a look.
📞 Call Absolute Plumbing & Heating today on 07852 130 372
Or visit our boiler repair page to book an engineer.
We’re Gas Safe registered and here to help, whether it’s a minor pressure tweak or a major system fault.
