If you’ve noticed your gas boiler in Guildford constantly losing pressure, you’re not alone. It’s a common issue that many homeowners experience—especially during colder months. Understanding the cause is key to keeping your home warm and your energy bills stable. As experienced engineers at Fuller Heating, we regularly help customers with boiler service and repair, gas and LPG installations, and related heating system maintenance. In this guide, we’ll look at the most likely reasons for pressure loss and what you can do about it.
Understanding Boiler Pressure
Your boiler’s pressure helps your central heating system circulate hot water effectively. The correct operating pressure usually falls between 1 and 2 bars at cold temperatures. If the pressure drops below this range, your boiler may shut down to protect itself. This is why understanding why your gas boiler keeps losing pressure in Guildford is so essential—it can prevent costly repairs and maintain home comfort.
Common Reasons Your Gas Boiler Keeps Losing Pressure
1. Small Leaks in the Heating System
Even the smallest leak in your pipework, radiators, or joints can cause gradual pressure loss. Leaks may not always be visible since they can occur under flooring or behind walls. Signs include damp spots or reduced radiator efficiency. A professional heating engineer in Guildford can conduct a pressure test to identify and fix the problem.
2. A Faulty Pressure Relief Valve
The pressure relief valve protects your boiler from overpressure. If it becomes faulty or stuck open due to debris or age, water will escape, leading to a steady drop in pressure. Your engineer can inspect and replace the valve if necessary to restore balance to your heating system.
3. Bleeding Radiators
Have you recently bled your radiators? While this process removes trapped air for better heating, it also releases some water from the system. Forgetting to re-pressurise your boiler afterwards is a frequent reason homeowners in Guildford find their gas boiler losing pressure soon after maintenance.
4. Expansion Vessel Problems
The expansion vessel inside your boiler absorbs excess pressure when water expands as it heats. If the vessel is faulty or its internal bladder has lost pressure, it can cause repetitive pressure drops. Engineers can recharge or replace the vessel to prevent future issues.
5. Hidden System Corrosion
Over time, corrosion or sludge build-up in your central heating system weakens components, causing small leaks and blocked pathways. Regular servicing and system flushing help minimise corrosion and extend your boiler’s lifespan. If your boiler is older, corrosion might be contributing to the pressure loss.
Steps to Diagnose Pressure Loss
Before calling a professional, try the following diagnostic steps to assess the cause of your boiler’s pressure issues:
- Check the pressure gauge—note whether it drops consistently after topping up.
- Inspect visible pipes and radiators for leaks or dampness.
- Observe if the pressure decreases only when heating is on, indicating an expansion vessel issue.
- Do not continue repressurising daily—it can worsen existing problems.
At any stage, if you suspect internal leaks or cannot locate the cause, it’s safest to call a qualified gas engineer to investigate safely and thoroughly.
Preventing Future Boiler Pressure Problems
A well-maintained heating system runs more efficiently and keeps pressure stable. Annual boiler servicing in Guildford is essential to prevent issues before they start. During service, engineers check for leaks, test pressure levels, and ensure all safety components function correctly. Installing a magnetic filter can also help by capturing sludge and rust before they reach sensitive parts of your boiler.
When to Call a Professional Heating Engineer
If you’ve ruled out simple causes like bleeding radiators but your gas boiler keeps losing pressure in Guildford, professional help is the next step. A certified engineer can assess whether your problem relates to internal leaks, valve faults, or a failing expansion vessel. Attempting to fix these independently can be unsafe and may void your boiler warranty.
Contact Fuller Heating for Reliable Boiler Assistance
Dealing with boiler pressure loss doesn’t have to be stressful. The experienced team at Fuller Heating provides expert boiler repairs and gas installations throughout Guildford and surrounding areas. We’ll quickly diagnose the cause and restore your system to peak performance. If you need help with your gas boiler in Guildford, contact us today for a fast, professional response.