Are some of your radiators too hot and others too cold? If so, you may need to rebalance them in order to increase the water flow to those that are cooler.
Balancing your radiators involves adjusting the radiator valves so that all of the radiators heat up at the same speed. Radiators that are too cool need more hot water flowing through them while those that are too hot need the flow restricted.
Balancing radiators is not a particularly complicated process, involving just a few simple tools. It is time consuming however, so make sure you only tackle it when you have enough time to set aside.
Radiator Balancing Preparation
Unless you are using self-bleeding radiator valves, you should bleed the radiators beforehand.
There might be some leakage from the valves when adjusting them, so ensure that you have cloths or paper towel underneath each radiator valve to soak up any seepage.
The tools you’ll need are an adjustable spanner (or lockshield valve adjuster) to open and close the lockshield valve, a screwdriver if the lockshield valve cap is screwed on, and a digital thermometer.
Familiarise yourself with the types of valves on your radiators. Each radiator should have a wheelhead or thermostatic valve on one side (the one you turn the radiator on and off or adjust the temperature with) and a lockshield valve on the other side (this usually has a push on or screw on cap on it which should be removed before balancing your radiators).
Turn the central heating off and leave all the radiators to cool completely before starting.
Balancing the radiators
Start by fully opening the valves on every radiator (both lockshield and wheelhead/thermostatic valves) by turning them anti-clockwise.
Turn the central heating on and make a list of the radiators in the order in which they heat up. Those closest to the boiler will usually heat up first. If you have quite a few radiators then you’ll probably need some help with this step. Once done, turn the heating back off and wait for all the radiators to cool down again.
Turn the heating back on and go to the first radiator on your list. Close the lockshield valve completely (turning it clockwise as far as it will go) then open it slightly (about a quarter turn anti-clockwise). Once the radiator is fully heated, take the temperatures of the pipe going into the valve on one side and the pipe coming out of the valve on the other side. You’re aiming for a 12°C difference between the two. Adjust the lockshield valve in tiny increments until you’ve achieved this. You’ll need to wait a few minutes after each adjustment to allow the temperature to change.
Once this is done, do the same on the second radiator on your list and then work your way through all the radiators. For the last one (the one furthest from the boiler and that was the last to heat up) you may need to have the lockshield valve completely open in order to achieve the 12°C difference – this is fine.
That’s all there is to it – your radiators are now balanced! The water flow has been evened out through each radiator and your central heating should work better and more efficiently as a result.