Hydraulic balancing

Balancing your heating system

Balancing your heating system is actually a very straight forward process, it can improve the operating efficiency, comfort levels and help reduce energy consumption in wet heating systems. Many homeowners are totally unaware of the merits regarding balancing of the system, a common sense principle that any decent heating engineer will use to make new and existing systems operate more efficiently.

Why the need for balancing?

Balancing of a heating system is the process of optimising the distribution of water through the radiators by means of adjusting the lockshield radiator valve which equalizes the system pressure, so it provides the intended indoor temperature at optimum energy efficiency and at minimal operating cost. To provide the correct heating output of each radiator, it requires a certain flow known as the design flow.

If the flow of water through the radiators is not balanced, the result can be that certain radiators can take the majority share of the water flow from the boiler, leaving other radiators with very little flow. This can greatly affect the boilers efficiency and home comfort levels as some rooms may be too hot or even remain cold.

There are also other potential problems. Thermostatic radiator valves (TRVs) with too much flow may not operate properly and could be noisy with water gushing noises through the valves, especially when they start to close as the room temperature rises.

What causes an unbalanced system?

One of the main causes is when radiators are removed for decorating and then refitted. This can affect the balance of the whole Heating system.

Also to overcome poor circulation and cure “cold radiators” sometimes people adjust the system pump onto a higher speed or raise the boiler thermostat onto a higher temperature setting.

 

This may or may not alleviate the symptoms of cold radiators, but it will almost certainly increase the energy consumption of the system even higher, and may also result in noisy radiator valves. It should be taken into consideration that a faulty pump may give a similar problem or a build-up of sludge in the radiators.

Given the benefits of system balancing, this process is an expected practice on new systems or boiler replacement installations and shouldn’t be neglected.

How Horsham Gas Engineer Andrew Tyler will balance your heating system.

Firstly I will remove air from the system by bleeding the individual radiators. Systems are normally balanced by adjusting the lockshield valves which are normally fitted on the return side of the radiator.

This ensures that each radiator circuit in the system has an equal pressure drop across it and receives the correct flow of hot water to heat the space in which it is fitted. The lockshield valve restricts the hot water flow to certain radiators in order to divert the flow to other radiators, thereby balancing the system.

Once any air in the system has been removed the heating is then turned off to allow all the radiators to cool down. I will then turn the central heating on and take note of the order in which the radiators heat up, those nearest the pump normally heat up first. If the pump is fitted inside the boiler then the radiator nearest the boiler normally heats up first.

Flow valves or thermostatic valves will be set to the fully open position and lockshield valves on all the radiators by turning them anti-clockwise. The plastic cap on the lockshield valve is removed and a small spanner or an adjustable spanner is used to adjust it.

With all the radiator valves fully open, I can check by touching them to see if they all heat up at the same time. If they do your radiator system does not require any adjustments. If the radiators are not heating evenly then the radiators which get hottest quickest will have the their flow restricted by closing the lockshield valve.

This pushes more flow through the remaining cooler radiators. To balance a poorly designed system it may be necessary to close down a valve more than 80%. Having restricted the return valves on the hottest radiators by 50% or even 60% to start with, I will then monitor the system performance.

The cooler radiators will start to get hotter. Some previously

cooler radiators may get fully hot. If some are still cooler, further adjustment is still required by restricting all the hotter radiators down.

Radiators which were previously restricted before are closed down further and some which weren’t restricted are restricted because they are now hot. I will continue to monitor the system, and where necessary, restrict the hotter radiators.

Any changes made to an individual radiator can affect all other radiators on the system

   

The use of a digital thermometer.

Radiator temperatures can be monitored by hand or by using a pair of clip on pipe thermometers on the flow and return pipes at either end of the radiator. Starting with the radiator nearest the pump (circulator) or boiler (if the pump is integral in the boiler), the lockshield valve is adjusted until the required temperature drop between the flow and return pipe is achieved.

This is typically 20°C for condensing gas boilers but always check the appliance manufacturer’s guidance. I will allow a couple of minutes after each adjustment for the temperature to stabilise.Then move on to all the other radiators in the order that they heat up.

Other methods.

Modern Thermostatic Radiator Valves like the IMI Eclipse can be balanced using internal settings on the valve body. I can select the correct setting from a “look up table” for a given room and radiator size combination.

The ultimate solution is to look at optimising the radiators output to match the room requirement. This is done by changing the return temp at each radiator. This can easily be

Automated Solutions

New solutions exist to make system balancing even easier. There are APPs like IMIs HyTools App that are available that can calculate the flow required for a specific radiator and then guides on how to set the AFC Eclipse TRV valve correctly for each individual radiator. These APPs can also provide a report detailing the properties heating system, any settings made, date of balancing and installer details.

Once the balancing is complete, the radiators heat up at an even rate and, in most cases the boiler can run at a lower temperature, increasing efficiency.

Covering Horsham District, Horsham, Southwater, Broadbridge Heath, Slinfold, Billingshurst, Steyning, Storrington, Ashington, Rudgwick, Cowfold, Pulborough, Warnham, Henfield, Bramber, Upper Beeding, Partridge Green, Rusper & Faygate.