Your combi boiler can be losing pressure for a number of reasons. Pressure loss may be caused from a leak in the pressure relief valve, an issue in the expansion vessel, air in your system, or a leak in the heating pipework itself..
Similarly, you may ask, why does my boiler keep losing pressure?
The most common reason for a boiler losing pressure is that there is a leak on the system somewhere. This could be a leaking radiator valve, a pipe or anything else that is causing water to leave the system. For example, the Pressure Relief Valve may be failing causing the boiler to lose pressure.
Subsequently, question is, can a boiler lose pressure without a leak? Note, however, that even if the pipework is wet to the touch, this does not necessarily indicate that there is a leak - it may be caused by condensation due to temperature differences. If your boiler continues losing pressure and there is no leak, then there may be a fault with the boiler.
Simply so, how often should a combi boiler lose pressure?
If the pressure has fallen to below 0.5 bar (often indicated by a red section), then it shows that some water has been lost out of the system and it must be replaced. The pressure in a central heating system will usually need to be topped up only once or twice a year.
How often should you need to top up boiler pressure?
Topping up once or twice a year is normal, but it will dilute the corrosion inhibitor, so maybe add some every five years.
Related Question Answers
What happens if boiler pressure is too low?
The good news is that low boiler pressure is nothing to panic about and is not likely to cause any damage to your boiler. On the other hand, it can have a real effect on the efficiency and effectiveness of your heating system, making it hard to keep your house warm and costing you more on your energy bills.How do I find a leak in my central heating system?
Place a sheet of colored paper under the boiler – if any drops appear on the paper, it should make it very easy to find the leak in your central heating system. Follow the wet spots up along the central heating system and see if you can spot where the water is coming from.How much does it cost to replace a pressure relief valve?
A replacement valve costs around $20 and calling in a professional could bring your cost up to $200. This isn't a steep cost to ensure proper diagnosis and installation. The pressure relief valve is there as a safety measure in case the pressure inside the tank gets too high.How do I fix the pressure on my boiler?
How do I re-pressurise my boiler? - Switch off your boiler and allow it to cool completely.
- Find the filling loop and check that both ends are securely attached.
- Open both valves to allow cold water to enter the system, keeping an eye on the pressure gauge.
- Close both valves when the pressure gauge reaches 1.5 bar.
Why does the pressure on my Worcester boiler keep dropping?
If you are constantly losing pressure in the heating system you could try the following to establish the cause: Check that there is no water being discharged from the pressure relief valve (sometimes referred to as an overflow). This pipe usually goes from the boiler through to an outside wall and terminates outside.Does boiler pressure go up when heating is on?
The pressure on your boiler's gauge will increase when the heating is running. But, your boiler shouldn't rise more than 1 bar during its heating cycle. If your boiler heats up more than 1 bar (or close to 1 bar) during start up, there's a good chance there's a fault with the expansion vessel or pressure release valve.Can a boiler explode?
While historically, boilers would over-pressurise and explode with alarming regularity, modern boilers are manufactured to be able to withstand excessive pressure, and can typically handle an operating pressure of 20 PSI. When pressures increase beyond this level, the boiler can fail, which can lead to an explosion.Does bleeding radiators affect boiler pressure?
Bleed your radiators. This reduces the pressure in your central heating system and therefore reduces the pressure in your boiler. Continue bleeding the radiator after you have expelled all the air from it until the pressure gauge returns to safe levels.What should boiler pressure be when heating is on?
What pressure should my boiler be? Generally, your boiler pressure should be between 1 and 2 bar. However, read your boiler's manual or ask your heating engineer for the required pressure for your particular model. To check your boiler's pressure, you need to locate the pressure gauge on your boiler.Is low water pressure dangerous?
Low Water Pressure is not necessarily a dangerous condition, but may result in inconveniently low pressure to your water fixtures and may be a sign of problems in your home water system.Does boiler pressure fluctuate?
It's perfectly normal for the water pressure to go up & down. When the heating is on the hot water will expand which raises the pressure. On a modern sealed system there is an expansion vessel which allows the water to expand as the pressure increase because it is hotter without causing leaks.Why is my boiler dripping water from the bottom?
A boiler leaking water requires the urgent attention of a heating engineer as it could lead to serious damage. Corroded pipes, high pressure and loose joints are all common reasons of a boiler leaking water and if your boiler was only installed recently, the leak could be down to poor installation. 
