Can a boiler lose pressure without a leak?
Even though in the vast majority of cases the cause of low boiler pressure is a leak of some kind, whether it is big or small there are other reasons why your boiler pressure has dropped. If you can be fully sure that you don’t have a leak anywhere in your boiler or central heating system, then it’s important to find out why your boiler has lost pressure so it can be fixed quickly and effectively. In this article we will be looking at the other causes of pressure loss in detail to help you get an insight into what might be affecting your pressure.
Expansion vessel
When your heating system is on, the water starts to expand, and the vessel works by removing that water expansion from the heat. The expansion vessel contains a lot of air and counteracts any increasing pressure that might occur in your pipes or radiator. However, if the vessel is never repressurised or a fault develops with the part the pressure within your boiler system will be affected.
More often it will be that the pressure actually rises too high when there is a fault with the expansion, but this in turn signals the pressure relief valve (PRV) to release all the pressure, leaving it at 0 bar. A problem with the expansion vessel is not something you can diagnose yourself and will require a specialist Gas Safe registered engineer to resolve the problem.
Pressure gauge
It is a pretty uncommon issue but occasionally there could be a problem with your boiler’s pressure gauge. This means that the part is unable to detect the correct level of pressure in the system and can be problematic if you continuously repressurise the boiler when you don’t need to, leading to more serious damage. If you notice that the gauge doesn’t change when you increase the pressure on your boiler and the cause isn’t a leak, then it could well be a fault with your gauge, and you will need a boiler pressure gauge replacement.
Filling loop left open or faulty
If you attempt to repressurise your boiler when you see the pressure drop to below 1 bar it’s important to make fully sure that you have closed the filling loop completely. When the loop is left open even slightly it can mean too much water will flow into the system and affect the pressure. If you are certain that the valve and loop were shut off as far as they could go it might be that they have become worn over time or dirt has got in and is preventing them from closing all the way. In any case, the valve should be checked and potentially replaced if required.
Pressure relief valve
The pressure relief valve in your boiler acts as a safety device, releasing a build-up of pressure if it becomes too high. If the valve isn’t functioning as it should be the boiler will start to leak and the pressure will drop. It’s important that every other possibility has been checked before the pressure relief valve is replaced. This is because if the valve is replaced and the pressure keeps increasing then something else is making the pressure rise and your new valve will start leaking too. You can find high quality boiler pressure relief valves at NBS.
Conclusion
Going back to the overarching question of this guide, yes! A boiler certainly can lose pressure without their being a leak. As we have seen above, if you don’t have a leak in your boiler system it could be a fault with one of your parts that needs checking. At National Boiler Spares we are committed to providing quality and affordable new and refurbished boiler parts.
Reusing spare parts for boilers that are in good working order is not just more cost effective but is also environmentally friendly too. Not sure what part you need for your boiler? Don’t worry, our team are on hand to help you find the exact component you need to get your boiler up and running efficiently. Simply contact us if you have any questions.