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Central Heating Circulating Pump Speed Setting Guide

Central Heating Circulating Pump Speed Setting Guide.

After installing a central heating circulating pump, you should ensure that the pump is set to the right speed, otherwise you might not get the correct amount of water warmed at the right temperature and in the most energy efficient way.

Finding the right pump speed depends on a lot of factors. Though it may be hard finding the best settings for the system installed in the property, this guide will provide useful tips to help you to identify the most appropriate central heating pump settings.

What Is The Function Of A Central Heating Circulating Pump In The Heating System?

The central heating circulating pump is a component that is designed to pump hot water originating from the heat source at the boiler to the radiators that are installed all over the system. After the water in the radiators has cooled, the central heating pump also returns the cool water back to the boiler for more re-heating.

Why Does The Central Heating Circulating Pump Have More Than One Speed Setting?

Most pumps have different speed settings. The main reason for this is that manufacturers (Gundfos, Wilo, Lowara, CPL, Stuart Turner, DAB & Flomasta etc) design different types of heating pumps with varying capabilities.

For a central heating pump to distribute water effectively in a system it has to overcome the friction between the water and the components of the heating system. Each central heating pump usually has a different number and this affects the number of radiators that it can support. Additionally, each heating system usually uses pipes of different diameters and lengths. The boilers that serve water to the central heating pump also come in varying sizes.

The factors mentioned above affect the friction in the water being pumped and the installed system. In order to overcome the friction between water and the heating system, central heating pumps need to operate with different speeds and power.

Manufacturers therefore produce these pumps with different speed settings so that installers can calibrate the pumps to a speed that allows for water to be pumped effectively.

What Are The Effects Of A Central Heating Circulating Pump Operating At The Wrong Speed?

During the installation of a heating system, most installers tend to take into account all the relevant factors before setting the pump to its optimal speed.

However, if the installers did not calibrate the correct speed settings or someone has messed with the speed settings, the central heating pump will not work correctly.

If the speed of the central heating circulating pump is too fast:

  • The pump and the pipes could create a noise.
  • Could cause a lot of electricity wastage.
  • Air calould seep into the system easily, hence the need for radiator bleeding.
  • The pump could be exposed to a faster rate of wear and tear.
  • The boiler could cycle on and off too fast, because water taken to the radiators is being recycled too fast and not cooling off enough.

If the central heating pump operates at a speed that is too slow:

  • Since the water being taken to radiators takes a long time before going back to the boilers, radiators will might not warm enough.
  • The boiler could overheat and cut out automatically.
  • Water being taken back to the boilers could come at a temperature that is too low.

How Much Electricity Does A Central Heating Circulating Pump Use To Operate?

The amount of electric power used by a heating circulating pump usually varies depending on the size of the pump being used in a system.

The model of the pump that is being used will also influence the amount of electric power being consumed.

The speed settings of a pump also affects the amount of electric power being consumed. For most central heating circulating pumps, a higher speed usually reflects into a higher rate of electricity consumption. A low speed usually translates to less power consumption.

For individuals seeking to make the high savings on energy costs, it is usually recommended that low speed central heating pump settings are used.

Types Of Speed Settings Available In Central Heating Circulating Pumps.

There are four speeding settings commonly found in most central heating circulating pumps. 

They are:

Single Speed Setting

Due to technological advancements, it is very rare to find a pump that operates under a single speed. However, you can still find pumps with this setting on the market.

Multiple Fixed Speed Settings

Most pumps offer Installers the choice of choosing between three distinct and individual pre-set speed settings. However, you can still find some pumps with more pre-set speed settings.

Variable Speed Settings

There are some pumps whose speed can be tuned to a variable setting. Installers of these pumps usually set the speed to vary depending on the heating needs of a property and other factors.

Combined Speed Settings

There are some manufacturers who design and produce pumps such as Wilo that have both pre-set fixed speed settings and variable speed settings.

How Do You Set The Speed On A Central Heating Pump?

The process of setting the speed of a central heating pump varies

depending on the type of pump in a system, and the heatingbpump brand and model.

However, most pumps have a well-labelled and highly visible control which installers can use to set the speed of the central heating pump.

Some of the most common controls for adjusting the speed that you may see in most pumps are a button with lights indicating desired speed or a calibrated rotary dial.

How Can You Identify The Best Speed Settings For A Central Heating Circulating Pump?

The Basic Method

As stated above, you should try to ensure that the central heating circulating pump is operating at the lowest speed if you want to lower electricity consumption. To find the lowest optimal speed settings, you can try varying the speed of the pump from high to medium to low while checking whether the radiators are heated to your satisfaction. You should also check to see whether the boiler is cut off or over heating as you change the speed settings. By varying the settings, you can identify the most appropriate speed for your pump.

The Advanced Method (Pump Curve)

Theoretically, the optimal speed settings in a central heating pump should ensure that there is 11 to 12-degree variance in the temperature of the water that is leaving the boiler and the water that is being returned from the radiators. It can however be difficult to put this into practice. This theory is based on the fact that the speed of the pump usually affects the temperature of water being returned to the boiler.

If your heating system uses a condensing boiler, you should ensure that the water being returned to the boiler does not have a temperature exceeding 55 degrees. Water above 55 degrees can reduce the efficiency and effectiveness of the boiler.

In order to use the advanced method of calibrating speed settings of a central heating pump, you need to use the pump curve diagram that's supplied with the pump, and a thermometer.

Even after measuring the appropriate theoretical temperatures and setting the speed of the pump via the pump curve, you should also watch out for other factors that may hint that the speed is not optimal such as extreme noise during operations, lack of proper heating in radiators and funny noises emanating from the boiler.

To reduce the amount of electricity being consumed by the pump, use the lowest optimal speed settings.

Top Signs That You Need To Adjust The Speed Settings Of A Central Heating Pump

If you have had to bleed radiators and they are still not getting hot, it is usually an indicator that the pump speed may be too low. To remedy this, the speed can be increased slowly. However, if the boiler starts overheating or radiators need bleeding more frequently, you may have increased the speed too much.

If the pumps and pipes start getting too noisy and radiators require bleeding regularly, it may an indicator that the speed is too high. The speed can be reduced to get rid of these problems.