Boiler Pressure Too Low – What It Means And How To Respond
Boiler pressure too low can be a scary thing to deal with.
After all, how does it actually work inside that big, white boiler? The designs of combi boiler systems are made to be economical, functional and reliable. But like any piece of equipment, it might need a checkup to ensure it runs efficiently. We’re here to talk about that.
Take a look at your boiler’s pressure gauge. It should have a green area highlighted that covers between 1 and 1.5 – if your boiler pressure falls below this then it’s currently too low. To correct this, try the following steps:
- Turn your boiler off.
- Locate your filling-loop.
- Turn the filling loop handle(s) to match the direction of the pipe.
- Watch the pressure gauge – when it returns to the green area, return the filling loop handle to the 90 degree position.
- Turn the boiler back on.
If you’re not industry-savvy, you may fall victim to easy persuasion by anyone looking to make a quick buck. Don’t be scared into thinking your only option is to get a new boiler. This doesn’t have to be the case.
However, there is one question you’ll need an answer for – Is your boiler pressure too low? Firstly, don’t panic. This doesn’t necessarily mean there’s anything wrong with the boiler.
It’s not ideal that your boiler pressure is too low. However, it’s even worse if it’s too high, as that’s where real damage can occur.
But what does low boiler pressure mean? How can you deal with it? And how can you prevent it from happening again? Fortunately the response ts a very simple and easy response that won’t cost you extra money or stress.
More importantly, we’ll look at how you can solve the problem of low pressure without any hassle.
Boiler pressure too low – How can you tell?
Are there other symptoms for boiler pressure too low?
Take a look at how your radiators function – do they fail to heat up the way you’d expect? Radiators will always struggle to provide heat if your boiler pressure is low. Take a look at radiators that are higher up in the property and pay attention to how much they’re heating up. Do the tops stay cold? If they do, then low pressure will likely have something to do with it.
The big question – Why?
Low boiler pressure is typically a result of a water leak or recent radiator bleed. These reasons are simple enough, but now you can go through a process of elimination to find out specifically why it’s happened.
A build up for magnetic sludge will mean you’ll need to have a chemical or a power flush, but it won’t be the reason for your low pressure, so it’s worth making the distinction.
If it’s a water leak – how can you find it?
The first thing you need to do is conduct a visual examination of the pipework. A leak could be anywhere – including what isn’t readily visible. Look for water on the pipework or any stains and swelling on the skirting board. Joints and bends are a common place for leaks, but nowhere moreso than radiator valves. This is where leaks can occur most frequently but it often overlooked, so keep your eyes peeled!
Leaks can often be found in bends in the pipework.
I’ve recently bled my radiators – how does that affect the boiler pressure?
If this is something you’ve done recently to improve the performance of your central heating system, then it will directly affect the pressure of your central heating system. Radiator bleeds are performed to remove air that has built up over time, causing portions of the radiator (usually the top) to remain cold. If this is the case, then the pressure level won’t return to normal by itself, you’ll have to top it off manually.
If you’re looking for detailing instructions, please read our ‘How to bleed a radiator’ article.
Are there any risks with having boiler pressure too low?
Leaks are checked and radiators are bled – Why is boiler pressure too low still?
Well for one, you don’t have to feel hopeless. Even if you’ve checked for leaks and haven’t performed any radiator bleeds, there are still other reasons for your pressure too low. It might be a problem with your boiler, or worst of all, there may be a leak on the internal heat exchanger but if it’s one of these two reasons, you should definitely consult a professional. Besides these causes, you can also repressurise the system if the needle on your pressure gauge is still between 0 and 1. When this happens, you’re letting water back in through the filling loop. If you’re confident enough to do it yourself, you can do so by following some very simple steps.
How to repressurise the system
- Find your filling-loop and pressure gauge. If you’re repressurising, the needle on the pressure gauge should still be pointing below 1.
An open filling loops looks like this. Note the black handle is facing the same direction as the pipe.
For the filling loop, the handles need to be at a 90 degree angle to the flow of the pipe.
- For best results, turn your boiler off before repressurising. It should be fine, but you can always wait for the unit to cool down before going any further.
- Turn the filling loop handle(s) to match the direction of the pipe. You should immediately hear water flowing through the pipe and back into your system. Keep it open until the pressure gauge stays within the green area (usually between 1.5-2)
- Once it’s reached the green area, return the filling loop handle to the 90 degree position. You should hear the water stop straight away.
- Turn the boiler back on. You may also need to press the reset button. If this is the case, it’s because the low pressure safety device on your boiler has been activated.
Continue checking the pressure gauge. If the pressure gauge stays in the green then you’ve done it correctly and everything is back to working order! The number one rule to remember at this stage is never leave your filling loop on. This is because it might allow too much pressure to build in the system and cause a lot of damage.
When the problem persists…
If you find that over time the pressure has dropped again, then there’s likely another issue that would need a professional assessment. You can always try repressurising the system again or carry out another radiator bleed but whether you’re dealing with a Viessmann boiler, Vaillant or an Ideal boiler your next move should probably be to speak to an expert.
If you’re topping up the pressure in your system twice a year, you can consider that relatively common. However, if it’s more like once a month and no leaks are found, there may be a problem directly with your boiler. At this point, you should seek expert advice.
If you have any questions about your central heating pressure or are looking into purchasing a new boiler, you can call Boilerhut on 02920 099898 or alternatively, get a free online quote by entering your details below!
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