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How to balance your radiators

When your radiators are switched on, it’s important to look out for hot and cold spots throughout your home. While cold spots in radiators are often the result of sludge in your system (which can easily be resolved through a powerflush), a powerflush may ultimately not be necessary and chances are your radiators just need to be balanced.

Well, why aren’t my radiators heating up at the same time then? Normally, this is due to hot water from your boiler not being distributed properly due to the distance it must travel. This means that the radiators nearest the boiler are more likely to be heated first and receive the most heat, whereas those further away take far longer and need adjusting to be balanced completely.

The process of balancing your radiators is fairly time consuming, but can be pretty straight forward once you repeat it for each radiator. Soon you’ll be well on your way to an evenly heated home!

Before you go ahead and start balancing your radiators…

What is a powerflush?
A powerflush is usually carried out by a qualified engineer who will attach a pumping unit to a central heating system to circulate cleaning chemicals at high pressure. The pump combined with the chemicals will actively clean your system and flush away any debris or sludge. The chemicals used will also remove limescale build-up, and a corrosion inhibitor may be introduced to prevent any rust from forming down the line. Once the water has been flushed, all the contaminated water is removed and disposed of by the engineer as part of the process. If during the process some stubborn deposits or blockages are found, the engineer will use tools to dislodge them. The powerflush process should only take about a day to complete (usually between six and ten hours) depending on the age of your heating system, the number of radiators, and the amount of sludge and debris build-up.

How do I bleed my radiators?
You will have to start bleeding your radiators to ensure that the efficiency of your home’s heating system is maintained to a high enough standard. Over time your heating system will begin to show signs of wear due to continuous use, which will cause air trapped air, and hot water won’t be able to circulate properly. Excessive amounts of air in your radiators will stop them heating up quickly and evenly. The reduction in the efficiency of your household’s heating system will probably cost you more money as a result. Bleeding is quite a straightforward process and doesn’t require an expert to do it. So, if you’d prefer to tackle the problem yourself and you have your tools at the ready, you could give it a go! Knowing how to bleed a radiator is essential to avoid paying extra for heating bills.

For more information, check out our guide on how to bleed your radiators here.

What are the different types of valves?

Manual radiator valves
You are likely to find a manual valve on most radiators due to their simple “on and off” nature. Manual valves are the most common type of radiator valve and allow you to twist the valve to allow water to flow through it or stop water flow. Despite manual valves being the easiest to use out of all other valve types, it’s important to note that you can’t monitor the amount of water or decrease the hot water flow unless you switch the entire valve off, which cuts the water supply to the radiator. So, if you are looking to make a big cut to your energy bills, you may want to take a look at the other valve options below.

Thermostatic radiator valves
Thermostatic radiator valves (TRVs) are far more intelligent than your bog standard manual radiator valves. TRVs give you control of your radiator’s temperature by turning a dial. The extra control of the output from each radiator will save a lot of energy, especially if individual rooms like your bedroom, for example, aren’t in use during the day. Once the surrounding temperature has reached the desired level, the TRV will regular water flow and only use as much as is needed, rather than wasting hot water and energy. If you are planning to have TRVs installed, it’s advised that you install them away from a room thermostat, especially if a radiator exists in the same room as the thermostat. If you had a TRV installed in the same room as a thermostat, your boiler would continue to shut on or off without knowing if the valves on the radiator have reached the correct temperature.

Lockshield valves
Lockshield valves are installed to control the water that flows back out of the radiator to the return pipework. You will find these valves covered by a plastic cap. Lockshield valves are essential to the balancing process.

You can read more about radiator valves here.

What tools do I need to balance my radiators?

  • Lockshield valve adjuster/adjustable spanner
  • Radiator bleeding key
  • Digital thermometer/multimeter with thermometer


  1. First, you need to make sure you bleed your radiators to remove any trapped air within them. Check out our guide on how to bleed your radiators here.
  2. After you’ve bled your radiators and checked that they heat evenly, you need to switch off your heating completely to allow all your radiators to cool down.
  3. Take note of all the radiators in your home on a spreadsheet or a piece of paper. You will need this later once you’ve opened all the valves and switched your heating back on.
  4. For the next step, you need to open the radiator valves on each radiator completely by turning them anti-clockwise. You can easily open your manual or TRV (thermostatic radiator) valves by hand. The lockshield valve will come with a plastic cap, which you need to remove and turn the metal valve with a valve adjuster or adjustable spanner.
  5. Once your valves are open, you need to switch your heating back on. This is the part where your pen and paper/spreadsheet comes in. In each room, check which radiator is heating up first. Normally this tends to be the one nearest the boiler. On your paper or spreadsheet, note down next to each radiator (in order) as they heat up one by one.
  6. Now it’s time to turn off your heating again. Once your radiators have completely cooled down, switch your heating back on again. Go to the first radiator on your list (i.e. the one that heated up first) and turn the lockshield anti-clockwise until they are completely closed. Once the radiator has heated up, take a temperature reading at the pipework connected to the lockshield.
  7. Take the temperature of the pipework leading to the manual/TRV valve, then slowly open the lockshield valve until the temperature reading is a 12-degree Celsius difference from the first reading you took in step
  8. Repeat these steps for each of your radiators, and by the end you will have a balanced radiator system!

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