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How to Fix a Boiler

9 times out of 10 heating and hot water related issues are a simple fix and can often very easily be solved by the tenant, here we hope to be able to provide you with enough information to avoid waiting for an engineer. What is the issue and how can we help?

Boiler not working – refer to part 1
No hot water – refer to part 1
No heating – refer to part 1 followed by part 2, followed by part 3
Cold rooms/radiators – refer to part 3
Boiler switches and functions – refer to part 4

Boiler not working?

Boiler Pressure Gauge

Check your pressure dial, which is often located at the front of your combination boiler, this typically should read between 1-2 bars, if it is below the red minimum level there’s a good chance your boiler is not working because of low pressure.

Pressure looking OK: If the boiler pressure is between 1 and 2 and you are still not getting any hot water or heating please refer to part 2.

Low pressure: If you have identified low pressure and have checked for leaks you may go ahead and top up the pressure in your closed loop system, please follow these steps to do so.

Boiler Filling Loop

To top up your pressure, identify the filling loop system located below the boiler, it may look like the picture above.

At each of the filling loops there will be two taps, locate these and then open one and SLOWLY open the second, you should then hear the system starting to fill.

Keep a close eye on the pressure gauge and allow the pressure to increase to 1.5 bars. When this has reached 1.5 quickly turn off the tap.

Turn on a hot water tap, after a few moments hot water should start to pour and you will hear the boiler fire. If the water is still cold the boiler may need to be reset, which you can do by simply turning it off and on again via the rest button.

Before attempting to top up the boiler, check the property for any obvious central heating leaks. These would most likely be from below a radiator or beneath floor boards and can often be identified by a water mark on the ceiling below.

Check your thermostat

Thermostats can come in a number of different forms with digital and analogue being the most common, they will typically be situated in a communal area to allow an even distribution of heat among your home, most new dwellings will come with thermostatic valves on the radiators to allow individual temperature selection in different rooms.

Analogue thermostat

Analogue thermostat

Simple and reliable functions, set the thermostat to around 21C (room temperature) and the boiler will then come on automatically when the property cools and will automatically turn off when too hot. Please note, that turning the thermostat to a high temperature will not cause the property to heat up quicker. Using the thermostat in this way will just over heat the property and lead to excessive energy usage.


Digital thermostat

This works in a similar way to the analogue thermostat and the temperature can be set accordingly, often digital thermostats have the added benefit of a timer
and/or can also be wireless so please check the batteries if the unit does not appear to be functioning correctly

If the thermostat is turned all the way down or the timer is set incorrectly this may cause the boiler to not turn on and heat the home when required.

Radiators are cold

If you find your radiator is not getting hot, perhaps your thermostatic radiator valve is turned down or it is possible that air has collected within the closed loop heating system and your radiators. In this case you can bleed your radiators in order to allow more hot water to flow into them, please follow the steps below.

Thermostatic Radiator Valves (TRV`s) are a highly effective way of regulating temperatures throughout rooms in your property as they can individually regulate the temperature of a specific room.

Simply turn the dial to set to your desired temperature, typically these are numbered 1 to 5 with 1 being the lowest.

You may need to purchase a radiator key if one is not present in the property, these can be purchased from most hardware and supermarket stores. Often radiators can be bled using a flat head screw driver.


You will need a bucket, bowl or pan; anything you can find to collect any excess water that may come from the bleed valve.

Insert the key into the bleed valve as shown above.

Turn the key anti clockwise to open the valve (righty tighty, lefty loosey!) you should hear a hissing noise as the air escapes.

When the air stops hissing and water squirts out, quickly close the valve. Repeat this process for every radiator in the property to ensure the entire system is free of air.

Before bleeding radiators please make sure the TRV’s are fully turned on.

Once this process is complete please check your boiler pressure to ensure it is within the normal parameters, this process may reduce pressure resulting in the system requiring topping up before the boiler will function correctly, please refer to part 1.

Boiler switches & functions

Most boilers have 4 main functions depending on the boiler and some of these functions maybe integrated into the thermostat. Part 4 will explain the various functions and hopefully help you assess any issues.
on and off button

On/Off/Reset, these are self-explanatory.  Reset is useful after topping up your system and the boiler is in need of re-lighting, in this case flick the switch to reset and back to on.

You may see a picture of a radiator and a tap and/or both of these images together.  These relate to the hot water and heating within the property, it is often the case that in summer the heating is turned off and only the hot water selected to save energy (we strongly recommend this), however when winter starts please check that the dial is turned to the tap and radiator option in order to supply both heating and hot water simultaneously.

Temperature gauge

Water temperature, is often  indicated by a thermometer symbol.  If water is coming out of the tap extremely hot and you find you are having to turn the cold tap on to compensate, then you are wasting unnecessary energy. Turn this dial and check the water temperature to locate the heat you require. Often you can also select the radiator temperature, the same rules apply.

Timer; either a digital or analogue clock which can be set to provide central heating when you require it throughout the day and to turn the system off when you don’t.  We strongly recommend this is set as most energy is used when the system is getting up to  temperature. If the boiler is used like a switch when you arrive in the property it will not work efficiently.

If you find your property heating extremely quickly causing the property to become uncomfortable, please reduce the temperature. The best way to regulate the radiator temperature is to use a thermostat if your property is supplied with one, in which case we recommend leaving this dial on the 50% mark.

Still not working?

Gone through the troubleshooting options above and still not working?