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Why Is My Boiler Pressure Low?

Your boiler is arguably the single most important appliance you have in your home. With a modern combi boiler, not only does it provide you with central heating to get you through the colder months, it also supplies hot water on demand - saving you both the space taken up by an immersion tank and the trouble of remembering to switch it on.

All in all, combination gas boilers are efficient, convenient and reliable. But like any appliance, that does not mean they are completely immune to little glitches and the occasional fault. It is still important to get your gas boiler serviced on a regular basis, to comply with safety regulations as much as keeping it in good working order.

Rather than major outages, it is far more common to notice that your combi boiler is not working as efficiently as you would expect. Perhaps rooms are taking a long time to warm up, radiators feel cool to the touch, and you’re only getting moderately warm water out of your taps.

The good news is, even if this occurs, the most likely cause is far from a major issue. The first thing to check is the water pressure. Your boiler should have a pressure gauge on the front, often a circular dial. The indicator should be between 1 and 2 bar. Any lower than 1, and it means water is not being pushed around your piping system efficiently enough once it is warmed up. That leads to radiators and taps alike not getting warm enough.

Water loss

Low pressure is a sign that water in the system is being lost somewhere. If you have bled radiators recently but don’t think it has made much difference to how your heating is performing, it could be because of the amount of water that escaped from your radiators. Bleeding lets air that has seeped into the system out via special radiator valves, meaning they can fill up with water more completely and therefore work more effectively. But if you have let out a significant quantity of water as you’ve tried to release the air, you could have caused the water pressure to drop below 1 bar.

The other likely cause of low pressure is a leak somewhere in the system. This is more of an issue, and can be hard to detect because the majority of your pipework is hidden away behind walls and under ceilings. Look carefully for any signs of standing water, moisture or damp in places you would not expect it. You will need to find and fix any leak to resolve your pressure issue long term.

Repressurising a boiler is very straight forward. Central heating systems are connected to your water supply via a pipe, usually located at your boiler, called a filling loop. It will have a valve at both ends which are usually in the closed position to stop water flooding the system. Switch off your boiler, let it cool and open both valves to allow water into your heating system. Keep an eye on the pressure gauge, once it is around midway between 1 and 2 bar, switch the valves off again. Your boiler should be back to working at its efficient best, and even if you do have a small leak somewhere, this serves as a temporary fix until you can get the source of the leak repaired.

We can help with low boiler pressure

For complete piece of mind for boiler care and repairs, why not sign up for one of Go Assists low cost servicing and maintenance plans? Contact us today for a free no obligation quote. 

*The information in this blog is designed to provide helpful information on the subjects discussed. Please seek a professional for expert advice as we can not be held responsible for any damages or negative consequences upon following this information.

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