HeatBoost Fan Radiator

HeatBoost Fan Radiator

HeatBoost radiators are the Harnitek fan coil radiators. The stand out feature of these radiators are that they will work with a significantly lower water temperature than a traditional radiator. So in simple terms you can turn down your heat pump, or turn down your boiler. Clearly this will save you money! But there are many more reasons to look at the HeatBoost radiators.

These units have many additional advantages over standard radiators. In particular they have an integrated fan which allows for much greater air flow and therefore much faster performance. They are extremely light, only have 1 litre of water inside hence remarkable reaction speed. They only need 35 degrees water flow, they have only plastic and copper internal parts and so will not deteriorate or develop sludge and need flushing out. They use a very small amount of power to run the fan, they are quiet and have variable fan speed options. They are cold to the touch and so are safe as you cannot burn yourself on them. Lastly and importantly if they are hooked up to a heat pump they can work as cooling as well as heating, so in those crazy hot days you can cool your environment.

The units come in just 4 different sizes, as they are all fan assisted they are capable of covering a range of output requirements.

HeatBoost Radiator Vs Modern Convectional Radiator Comparison

We have created a comparison chart to show the heat output at both 65 and 55 degrees to compare the HeatBoost to standard Steel Radiators.

This is only a method and a simple guide to show how to compare. We would ask that you use your own data from your particular steel radiator supplier to work out the results.

We have used both 65 and 55 degrees as many householders will chose to turn down their boilers when they gain the significant boost that the HeatBoost radiators generate.

For the full range of heat output temperatures from 35 – 70 degrees flow rate please check out the data sheets for each unit.

HeatBoost Radiator Vs Modern Convectional Radiator Comparison PDF Download:

HeatBoost Graph

This chart is shows a graph of data from 3 standard steel radiators K1, K2 and K3 units in 1400 x 600mm dimensions. Also shown are the HeatBoost small unit – LM350 (894 x 580mm) and the larger unit – LM550 (580 x 1394mm).

The graph shows the comparison of the different radiators with a range of waterflows, and the amount of heat output in watts.

The HeatBoost are efficient from waterflow as low as 35°C which would only be used for systems such as Heat Pumps running at the lowest temperatures – ie in the most efficient settings.

The chart shows a progression of low temperature heating temperature suitable for renewable heat sources shown in blue.

As the heat sources increases up towards 50-55°C where the application would be for standard boilers which have been turned down and new build installations. At these temperatures it is very clear that Heatboost units are considerably greater heat output than the standard steel radiators can achieve.

Moving higher up to from 55-70°C which would be for standard heating system using gas, oil or electric, then the gap is significant.

This graph gives a snapshot of data just outlining the significant output of heat from standard radiators to the HeatBoost units.

*All data is taken directly from manufacturer websites. For comparison with specific radiators you can check the relevant data sheets and make your own comparisons.





The HeatBoost radiators can work with existing heating systems. They will generate a considerable amount of heat compared to your existing radiators.

The swap out, or retrofit of a HeatBoost is very simple, rarely requiring anything other the old radiator off the wall, and the new one on. The HeatBoost will require an electrical feed, this can easily bee spurred from an existing supply, or even a nearby plug socket.

The HeatBoost radiators will give out so much more heat that you may well decide to turn down the boiler – check with your boiler provider – meaning lower bills.

One or two strategically place HeatBoost radiators in your home can significantly boost your heating, meaning your house can reach temperature faster and the boiler turns off earlier. Clearly this will reduce the amount of Gas or electric your Combi boiler will consume.

The HeatBoost units have inbuilt fans to significantly increase the air rotation and therefore speed up heating the air in your home. Traditional radiators first have to heat the steel radiator, which then heats the air, the HeatBoost simple heats the air.

The heating and convection process is so efficient that the surface of the HeatBoost does not change, it remains at ambient room temperature, only the air in the space is heated. This is exceptionally efficient.

The HeatBoost radiators only have up to 1 litre of water internally, up to 10 times less than a steel radiator, so less water is required to be heated giving faster performance.

HeatBoost radiators are made with only copper and plastic internal components, meaning there is no degradation in performance, unlike steel radiators there is no sludge build up in the system.

HeatBoost radiators are fully individually programmable using a touchscreen LCD on each unit.


The HeatBoost radiators work extremely efficiently at only 35 degrees water temperature. For all heatpumps the lower the flow temperature the higher the efficiency of the system, therefore the lower the running costs – significantly lower.

The HeatBoost radiators only have up to 1 litre of water internally, up to 10 times less than a steel radiator, so less water is required to be heated giving faster performance.

The heat output is so great from the HeatBoost radiators that they remove much of the necessity to find large spaces for oversized steel radiators. One HeatBoost 550LM will supply the same heat output as 2 x K3 1400mm radiators. So less space and less installation time.

The HeatBoost radiators have LST (Low Surface Temperature) so are safe for many environments.

HeatBoost radiators are made with only copper and plastic internal components, meaning there is no degradation in performance, unlike steel radiators there is no sludge build up in the system.

Where the heatpump is capable the HeatBoost radiators can blow out cold air providing air conditioning in rooms as required. They are provided with condensate outflows if this is a required feature.

The electrical supply required for the HeatBoost radiators is tiny, from 20 – 40w of power only when the fan is running.


For homes with oil boilers the disruption of changing to a low energy system is considerable. All radiators would generally need to be replaced with larger units, and this is often not possible.

Instead, as with the Combi boilers you could consider simply making your existing heating system much more efficient by installing the HeatBoost radiators. This will significantly boost the heat output in the rooms meaning the existing system will simply run considerably less, using less oil, reducing your oil bills and energy usage.

It is not necessary to change all your radiators, one or two strategically placed radiators may well have a significant effect on the amount of heat you are achieving.


Where you have underfloor, or plan to have underfloor heating you are already looking at lower temperature heating. Therefore the same problems apply with any other spaces you wish to heat in that you will require large oversized radiators to get enough heat out from the lower temperatures.

HeatBoost radiators give out extraordinary amounts of heat from flow rates as low as 35 degrees, so they are perfect to work alongside heating systems planning to use lower temperature heating.

Heatboost radiators are small and slim, and work using a powerful fan unit to quickly heat the surrounding air. Having only 1 litre of water inside the unit (compared to almost ten times that for large steel radiators), they react very quickly, heating quickly and turning off as room temperature is achieved.

Keeping your heating system operating efficiently at low temperatures will clearly save you money and reduce your energy usage. If you can then use smaller radiators with superior output to work alongside them you can continue to maximise your efficiency.


The waterflow required is only 35 degrees, so where you are using a heat pump this will mean you are running your hot water flow at 35 degrees and not 55 degrees, so your heat pump will be considerably more efficient. Check out the performance of your heat pump and you will see how significantly the performance drops off as you increase the water temperature. Lowering it will make it more efficient, so it will use a lot less electricity, so your bills will be reduced.

For some boilers you can lower the flow target temperature meaning the boiler will run much more efficiently. However for all boilers the amount of water in the heating system will be significantly lower, giving clear efficiency to the speed with which your home will be heated. So your house will heat up very quickly so your boiler will the switch off, so your boiler simply runs for a much shorter period.

Where heat pumps are installed the space requirement for oversized radiators is significant. For example a large room may require two K3 radiators at 600mm x 1400mm. This is a substantial size requiring a large area of wall space (not to mention the weight), the equivalent size for a fan coil is 1.3m by 600mm which is around 45% smaller. The fan assist function works by taking air in at the bottom, heating or cooling it through the unit and blowing it out of the top. Therefore the radiators can be mounted close to the wall without the need for a gap, thus giving them a slimline appearance compared to standard radiators which must have a gap

If there is a major cold period, then of course you can simply raise the heat pump temperature a bit, maybe to 45 degrees and possibly increase the fan speed also while it is at extreme conditions.

The internal components of the Cooler Flow radiators are copper and plastic, meaning the unlike steel radiators there will be no build up of dirt and ‘sludge’ in the system, so your system will remain in peak efficiency without needing to be flushed to sustain heat output.

When installing a heat pump to any retrofit it is standard procedure to increase the size of the radiators in order to achieve sufficient heat output. Typically you will increase the size of standard radiators by around 35% in order to change from fossil fuel temps of 65 degrees to heat pump temps of 55 degrees. This means much larger radiators are required, or in some cases more that one radiator is required. The Fan coil radiators are often either similar size or smaller than the conventional radiator, meaning swapping them out is very simple.

The weight of a K2 radiator xxx ft radiator when filled with water is 90 Kg. The equivalent sized Fan coil unit is 30 KG.

A standard large radiator will hold around 10-15 litres of water. The fan coil small to large units have 0.48, 0.85, 1.15 and 1.48 litres of water. Therefore the total water system is a fraction of the water volume of standard systems which is why they will heat up so efficiently. Importantly this very small water demand means that the heating process is more accurate. When the system reaches temperature it will power off so the system stops. Systems using large radiators with large volumes of water will continue to heat for a long period due to the overall energy created in the system. This is why overheating often occurs with traditional wet systems causing again significant cost due to the large volumes of energy required.

The Fan assist can simply increase the fan speed in order to heat larger areas, or react to the temperatures being colder, thus increases the output of the heating. A standard radiator cannot change.

Each Fan Coil radiator does require a power supply. Typically this is only 0.755 core supply as it only requires 1.04A per radiator. This equates to 25w of power when running. The unit can be supplied via a dedicated supply or from a plug socket.

All the heat exchange happens internally meaning that the outside surfaces of the Fan Coil units does not get hot at all making it extremely safe to have installed in any location.

The Fan coil radiators have a range of fan setting, or can simply be set to Auto mode. In Auto mode the fan coil will scroll down the fan speed as the temperature is getting closer to the target.

If the heat pump is capable of both heating and cooling, then the Fan coil radiators can also be used for cooling a room as well as heating. This introduces air conditioning within the same unit.

The LCD controls allow you to set quickly many simple settings. All settings are done by touch, the screen then locks until it is again unlocked to protect any accidental changes to the settings on the units. Target temperature,Fan Speed -fixed or auto, Sleep Mode (no fan), or On/Off functions are all at the press of a button.