Ultimate Guide to Balancing a Heating System

Balancing Radiators and Distributing Heat Efficiently

At one point or another, the chances are you have identified ‘cold spots’ on some or all of your radiators. When this happens, the first step is to grab a radiator key, a rag and begin the process detailed below to ‘Balance your System’.

Don’t worry, this a simple DIY job …. Just read on to find out how to do it.

What do you mean by Balancing Radiators?

No, we don’t mean holding them in one hand until you can balance them, like a clown might …..

What we need to do is adjust the radiator valves on each radiator in your home, in a set order to ensure the hot water is distributed equally, therefore ‘balancing’ the heating to ensure each radiator is heated equally.

Is bleeding a radiator the same thing?

No, although we need to perform this as part of the overall balancing of the system. Let me explain:

Balancing Radiators

In order to balance radiators, you need to allow more water to flow to the colder radiators and restrict the flow to the radiators which get too hot.

Bleeding Radiators

Bleeding a radiator is when you release pressure (trapped air) from the radiator valve, with a radiator key. If there is air trapped in the radiator, this will stop hot water from filling the entire radiator. Releasing this air, allows water to fill the radiator fully.

So, do I need to Balance or Bleed?

You need to do both.

To ensure you do this efficiently and to get the best balance in heating through all radiators in your home, you should bleed them first to remove any trapped air in the system.

  • Required Tools
  • Radiator Bleed Key
  • Adjustable Spanner
  • Screwdriver

Step 1: Turn OFF your heating

The easiest way to do this, is to turn your thermostat down to nothing. You can also turn the boiler off to ensure it’s not working. This will allow you to release the natural pressure in the system, rather then attempt to bleed the radiators while hot water is being pumped around the pipes.

Turn down Thermostat

If you don’t have a digital thermostat, just turn your conventional thermostat down to zero. This will stop the boiler from coming on. On your timer, set it to OFF or turn the boiler off.

Step 2: Bleed your Radiator Valves

You could just bleed the radiators which have cold spots but it’s probably best to run through all of them and bleed each one, to ensure you remove all trapped air.

Grab a radiator key and an old towel and go through each radiator in the house. Simply insert the key and turn anti-clockwise until you hear a hiss. Allow the air to escape and then re-tighten the valve. Don’t overtighten, just nip it up again.

Bleed radiators to remove trapped air

  • Turn key anti-clockwise a small amount (do not fully open)
  • Allow air to escape
  • Catch any leaking water with the towel
  • Re-tighten once all air has escaped

Move through the house, doing the same thing on each and every radiator until they are all bled.

Step 3: Open up all Radiator Valves / TRVs

Most properties will have TRVs Thermostatic Radiator Valves. On the other side of the radiator, opposite to the valve shown in Step 2, will be another type of valve. This is the thermostat valve which controls how how your radiator gets.

  • Open this valve up fully to it’s maximum setting by rotating it anti-clockwise
  • Do this for ALL radiators in the house
  • Read the step 4 before you start, as the valve opposite end also needs adjusting

Thermostatic Radiator Valve or TRV

Step 4 – Turn OFF Radiator

On the other side of your radiator is a valve, which often has a blank cover. See the example below. The ‘lock shield’ cover is often a push on style cap. It may work to turn the valve on and off, but quite often these are broken and a spanner is needed to turn the water flow up and down.

  • Rotate this valve clockwise fully until it doesn’t turn any more. This is OFF
  • Then rotate it anti-clockwise half a turn to open it a little
  • Do this on every radiator in the house

Step 5 – Check how your system heats up

Turn the boiler on and set the thermostat back to normal heat setting. Once the boiler kicks in and starts heating, make a note of which radiators heat up.

Radiators nearest to the boiler will often get hot first.

  • Make a list of radiators in your home in order of heat – (Warmest First and Coolest Last)
  • The hottest will be nearest to the boiler
  • The coolest will be furthest away from the boiler
  • When you make adjustments, you will start with the hottest radiator first

Step 6 – Turn Heating OFF and wait for radiators to cool down

Turn the thermostat down again to turn the boiler off and wait for radiators to cool down, so you can attempt to balance the flow of water and heat through your system. It is best to do this when the radiators are cool. In most cases, you can just turn thermostat down, but if needed, switch boiler off completely.

Step 7 – Turn Heating ON and begin balancing the system

Moving from the first radiator (closest to boiler) towards the furthest away, begin to balance the system.

  1. Turn the heating back on and go to the first radiator on your list which began to heat up first
  2. Turn the lockshield valve (from Step 4) so it’s OFF and then open it just a small amount (approx 1/4 turn) – Check Temperature
  3. Move to the next radiator and do the same. Shut valve off fully and then open a little bit more – Check Temperature
  4. Continue to do this until you reach the final radiator. For this one, open the valve fully to allow more water flow in – Check Temperature
  5. Turn TRVs fully ON for each radiator and check the temperature.

Step 8 – Make final adjustments and enjoy the heat

If you follow through these steps properly, you will have balanced your system and previously cool radiators in the house will benefit from extra hot water being pushed to them. No more cold spots and heat throughout the house.

To summarise, what you are doing here is limiting the flow of water for radiators closest to the boiler (by opening the valves just a little) and allowing more hot water to flow into radiators furthest away (by opening the valves fully).

Once balanced, you can adjust the TRVs to suit the temperature you require in each room of your home.