How To Balance A Central Heating System

Many people now have central heating systems installed at home where a centrally located boiler heats water which is pumped to radiators located in each room. If we have a new central heating system the likelihood is that it will be controlled by a programmable timer and thermostat, however even if you have all the latest electronic gadgets controlling when your heating comes on and off the system still might not work correctly if the system is not balanced.

You might notice a problem with an unbalanced system if some of the radiators heat up quickly but others don’t heat up at all or take a long time before they reach maximum heat. In any water fed system the water will take the easiest route through the system so if a couple of the radiators are located far away from the pump or are fed using microbore piping the hot water may ‘choose’ to flow through other radiators first, meaning some radiators will take a little longer than others to warm up. There is something that can be done to balance the system however.

Radiator balancing used to be done as a matter of course when central heating systems were installed but since TRVs were introduced the practice has sadly waned. But balancing a system should be done with or without thermostatic valves and this is the only way your central heating will work effectively.

Balancing is achieved at each radiator by adjusting the ‘lockshield’ valve at the opposite end of the radiator to the TRV. Basically when you adjust this valve you are adjusting the water flow rate through the radiator. This means that if the hot water is flowing through the radiator too quickly (seen if the radiator gets hot very quickly) the flow can be restricted by turning this valve.

To balance the radiators a certain process has to be followed which is best done by a heating engineer. However if you are a competent DIYer you can try to balance the system yourself.

Balancing a central heating system
o    Make sure the central heating is off
o    Turn all the TRVs to fully open (highest heat)
o    Take all plastic caps off the lockshield valves
o    Start at the radiator nearest the boiler and turn the lockshield fully clockwise, to turn it off, then open it a quarter of a turn
o    Go to the next radiator and turn the lockshield fully clockwise then turn the valve three-eighths of a turn
o    Carry on this process, opening each lockshield slightly more than the next on the remaining radiators until you are at the radiator furthest away from the boiler – this should have the lockshield fully open.
o    Turn on the boiler and pump and see how quickly each radiator heats up, if some heat up quicker than others adjust the radiator lockshield valves accordingly until each is balanced
o    Replace the plastic covers on the valves

Guest blogger Christopher Jenkins wrote this article on behalf of, Uk-based supplier of radiators.