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A sealed central heating system should generally maintain pressure for several years.
Boiler pressure might need to be topped up once a year. Any more than this, and it’s a sign of a problem.
Our team of experts are ready to fix your boiler pressure issues.
Why does my boiler keep losing pressure?
A boiler or central heating system loses pressure as water escapes. This could be due to either a leak in the system or a fault in a boiler component.
Normally, a central heating system is sealed, but built-in safety mechanisms are designed to expel water if the pressure exceeds a safe level.
What is the ideal pressure for a central heating system?
The pressure will change depending on whether the heating system is cold or hot. Aim for a pressure of 1.2 bar when the system is cold.
Cold = 1.0 to 1.5 bar
Heating = 1.5 to 2.0 bar
High but still safe = 2.5 bar
At 3.0 bar, the pressure relief valve should open, allowing water to be expelled via the overflow pipe and the pressure to drop.
Why is the pressure dropping every day?
The speed at which the pressure drops is usually a good indication of the severity of the problem. If a boiler is losing up to 0.5 bar of pressure a day, it indicates a significant amount of water is escaping the system over a relatively short period.
What are the possible causes of recurring pressure loss?
Leaks in exposed or concealed parts of a heating system are common causes of recurring pressure loss. Pinhole leaks in radiator panels, leaking radiator valves, and pipework leaks are all possible causes.
Faults in mechanical parts of a boiler are also possible causes:
Why is boiler pressure dropping when there is no leak?
Damage to the mechanical parts of a boiler can cause a boiler to lose pressure. Water could be expelled from the system via the external overflow pipe rather than internally. Damage to the primary heat exchanger plate could mean water is being heated inside the combustion chamber and evaporating.
It is worth noting that just because there are no visible signs of a water leak does not mean there isn’t one. Leaks can occur in pipes concealed beneath floors. These can be located, exposed and repaired using specialist trace and access methods.
A central heating system is repressurised by adding water through the filling loop.
Having to repressurise by adding water repeatedly is a sign of a problem.
Adding water without the correct inhibitor dose will increase the rate of internal corrosion.
Repressurising a heating system is usually straightforward. However, every time fresh water is added, dissolved oxygen speeds up internal corrosion.
Corrosion particles (rust) will damage the boiler’s mechanical parts and eventually cause blockages and leaks. The build-up of corrosion particles also reduces heating efficiency, resulting in higher heating bills.
If your boiler is losing pressure, book an Aspect heating engineer to diagnose the cause and fix the problem.
If a boiler is continually losing pressure, a leak isn’t assumed automatically. Our Gas Safe-registered experts can resolve all boiler pressure loss problems. They investigate boiler pressure loss problems in the following order:
Our Gas Safe-registered experts will first inspect the boiler for faults that could result in a loss of pressure, such as a damaged expansion vessel or pressure relief valve.
Checks are performed on the exposed parts of the system. Water may be escaping from pinhole leaks in radiator panels, corroded pipes or damaged valves and seals.
If visual checks fail to reveal a leak, a “trace and access” investigation using reliable, non-invasive methods, is conducted to locate leaks on concealed parts of the system.
We can repair every make and model of gas boiler. Our experts carry a stock of common replacement parts in their vans. When specific parts are needed, we have a huge network of trade suppliers to call on to source them quickly.
We install hundreds of new boilers every year, and are approved installers for the following brands. If replacing a broken boiler is more economical than repairs due to its age or condition, we can recommend a model for any property or budget. Our customers can also benefit from extended warranties when we fit these makes.
What a relief! Boiler pressure started dropping overnight, then twice a day. I gave up after looking everywhere for a leak, and having the boiler checked by the manufacturer.
Ricky from Aspect was great. Kept us updated, and explained the procedure every step of the way. Finally found a leak using gas detection, in a pipe embedded in the concrete floor! Fixed it quickly. Now all good.
Laurence, Upminster, RM14
We had a very good experience with Aspect. Our boiler was losing pressure. They had an expert out the next morning who arrived at 8am. By 4.30pm they had located a leak under the floor, fixed it and the room was tidy and warm. It was complicated needing gas run through the system. I had a query after and the technician was really helpful.
Jennifer, Holland Park, W11
What a relief! Boiler pressure started dropping overnight, then twice a day. I gave up after looking everywhere for a leak, and having the boiler checked by the manufacturer. Ricky the engineer was great. Kept us updated, and explained the procedure every step of the way. Finally found a leak using gas detection, in a pipe embedded in the concrete floor! Fixed it quickly. Now all good.
Laurence, Tunbridge Wells, TN2
Excellent service very responsive and professional tradesman. Kevin attended my property to find a leak in my central heating system he was very kind, professional and reassuring. His team were also very good. I would highly recommend.
Mrs Williams, Bexleyheath, DA7
Anton was exceptional. Despite being tricky to trace, he persevered and found the leak on the c.h. system eventually. He repaired the leak and reinstated the substrate. Every step of the way he was communicating very clearly about what he was doing and how far along the process he was. He was courteous, efficient, diligent, and effectively solved a problem we'd had for about 2 months. The boiler no longer looses pressure and finally we can at last relax about it.
Patricia, Banbury, OX17
Glenn was an amazing guy, helped me understand the issue with my boiler pressure and made sure everything is alright, he was transparent about all the costs. Definitely recommend getting him to sort any plumbing issues.
Catalin, Streatham, SW16
This video demonstrates how non-invasive methods are used to detect a hidden leak in a central heating system, following checks for boiler faults.
Several techniques are usually used during a thorough investigation.
Once found, our experts can access the leaks for repairs.
Half-Hourly Rates
Our boiler pressure loss investigation and repairs are charged in half-hour increments (1-hour minimum).
Boiler tests and checks for leaks on exposed parts of a central heating system are charged at our Heating & Hot Water rates:
– From £49.50 + VAT weekdays
– From £65.25 + VAT evenings & weekends
– From £85.50 + VAT late nights (9pm-7am)
Our Leak Detection rates will apply for trace and access investigation time needed to find a leak on the concealed parts of the system:
– From £54.00 + VAT weekdays
– From £69.75 + VAT evenings & weekends
– From £90.00 + VAT late nights (9pm-7am)
Use our postcode checker to get our best rates for your area.
If needed, a tracer gas charge will be added to the leak detection time.
There is no additional charge for emergency attendance when we aim to be on-site within one hour.
Fixed Price Reinstatement
Reinstatement work, which is needed to return walls, floors, or ceilings to their original condition, can be estimated at a fixed price.
We have Gas Safe-registered experts who can work on domestic and non-domestic gas supplies.
Our account team is ready to help customers across a wide range of commercial sectors, including: Food & Beverage, Hotels, Education, Healthcare, Property Management, Offices, Religious Buildings, Retail, Leisure & Entertainment, Sport & Fitness, Foreign Government, and more.
If a hidden leak is thought to be the cause of boiler pressure loss, our expert can pinpoint its position using non-destructive methods. Most insurance companies require the process we follow when dealing with an “escape of water” or “trace and access” claim.
If you suspect a leak in your central heating or plumbing system, you shouldn’t ignore it. Fixing the problem can usually be covered on an insurance policy.
Water escaping inside a property could be causing bigger problems than any visible signs might suggest. Similarly, continually topping up a central heating system with water to repressurise it is not fixing the cause of the problem.
Water damage can eventually compromise the structural integrity of a property if left unresolved. Failing to act quickly might mean your insurance company rejects your claim.
You can find out more about making a successful insurance claim in our guide.
