Balancing your radiators

A poorly balanced heating system can add a significant amount of cash to your annual bills.

Many people aren't aware of the impact that a poorly balanced system can have, and how much it can drive up your bills during the colder months.

Read on to find out the best way to diagnose unbalanced heating systems and what to do if yours are unbalanced.

Thinking about your heating costs this winter? Head to our tips for reducing your heating bills 

Why you need a balanced radiator system

The telltale signs of a poorly balanced system include some radiators heating up much faster, or getting much hotter, than others in your home.

Another clear sign is if certain parts of your house get uncomfortably hot, while other parts stay cool. 

In an unbalanced system, the temperature your home reaches may not match the one you set.  For example, when you set the thermostat to 20°C you would expect the whole home to heat to, and stay at, 20ºC.

However, with an unbalanced system, the upstairs might actually reach 23°C, while the downstairs remains relatively cool at 17°C. You may then be tempted to turn up the thermostat (in this example to 23°C), which will create a comfortable temperature of 20°C downstairs, but superheat the upstairs to 26°C. 

The Energy Saving Trust estimates that turning up the thermostat by just one degree costs an additional £75 a year in heating costs. So turning up the thermostat will just increase your bills, whereas getting your radiators rebalanced will save you money in the long run.

There are some tutorials online on how to balance radiators yourself, but it's best to get a professional to do this to ensure it's done correctly.

Why is my system unbalanced?

Your system can become unbalanced for a wide variety of reasons:

• Sludge and debris Old systems may be clogged up, causing blockages in some radiators, meaning they take longer to heat up. 
• Redecorating When radiators are removed and replaced, perhaps during decorating, this can impact the balance of the heating system.
• Misuse of Thermostatic Radiator Valves (TRVs) If TRVs have been fitted to radiators around your home, and not adjusted correctly, this can lead to system-balancing issues. 

Here's how to tell if you have inadvertently unbalanced your own heating system with TRVs: 

1. Turn all radiator thermostats to 0.
2. Turn the central heating off and wait for at least two hours for the system to completely cool off.
3. Turn all thermostats to 2, starting from the radiator furthest from the boiler if you have a combi boiler, or furthest from the water pump (usually found next to the hot water cylinder) if you have a heat-only boiler.
4. Check if all radiators get hot evenly at the same rate.

If they don’t, the system is not balanced properly. 

We would recommend that you call a Which? Trusted Trader to assist with what will be a much more technical method of balancing your heating system. 

How a heating engineer will balance your system

First they'll turn off the boiler for at least two hours for the system to cool off and then turn on the boiler from cold.

Next, they'll measure whether there is a flow differential (DeltaT) of at least 20°C at the boiler. and whether the return temperature is below 55°C (this is essential for condensing to occur, and for your boiler to be operating at its advertised efficiency).

If the flow differential is less than 20°C, or the return temperature is higher than 55°C, then the system is either unbalanced or the radiators are too small. Either way, you will need a heating engineer to fix it.

A heating engineer will first completely drain the system and remove any air pockets by bleeding the radiators. They will then refill the system with all of the radiator valves fully open. The next step will be to adjust the valves on the radiators that get hottest the fastest. This is to restrict the flow of water to the radiator and even out the spread of heat to the rest of your home.  

Costs for this will vary between £100 and £200, but expect the heating engineer to take at least half a day to complete the work. 

If you're ready to call in a heating engineer to balance your radiator, you can use our Which? Trusted Traders search tool to find an accredited trader near you. All of our traders have been vetted so you can trust them to do a great job.

If you decide it's time for a new boiler, make sure you buy from the best gas and oil boiler brands