Commercial over door heaters

Commercial over door heaters – the benefits & options

Commercial over door heaters are warm air heaters that are designed to maintain a protective barrier over the entrance to a commercial building or property. Many offices and commercial buildings require doors that are always open and this results in the inadvertent influx of cold (in the winter) or warm (in the summer) air into the building. Using a commercial over door heater or commercial over door air curtain as they are often referred to – will prevent this problem and ensure the separation of the indoor climate from outdoor conditions, in a unobtrusive and quiet manner, that does not disturb. Over door heaters should not be expected to entirely heat a wider space, as this is not their primary function. You can however, provide supplementary warm air heating when using a commercial door heater to provide a warm welcome.

Only properly designed commercial over the door heaters, working over the full width of your open doors will meet the requirements for a functioning air curtain heater. That being the width of the air curtain or over door heater should always be at least equal to the width of the commercial door that the unit is protecting and heating.

commercial air curtain heaters; commercial overhead door heaters;

Commercial air curtain heaters from Flexiheat UK

Over door heaters – What do they solve ? 

The main issues the resolve is – Heat Loss 

When a heated areas room door is opened, the outdoor or external cold air begins to flow through the lower area of the open door and the warm air from the room flows out via the top area of the door. This phenomenon causes an inevitable increase in the heat loss of the commercial building and also reduces the comfort level inside the room due to the penetration of cold air.

The solution ? Installation of a commercial over door heater / air curtain

By installing an energy efficient over the door commercial heater or air curtain, you create a heated air barrier between the indoor and outdoor climate and thus reduce the unwanted effect of cold air leaks into or the building and maintain pleasant heated environment for the occupants.

Operating Principle

The cold air enters the housing of the over door heater and passes over the heating elements ( for electric powered units) or heat exchanger ( for water fed / powered units ), then the heated air is captured by the fan and directs the air flow through special outlet nozzles that forms a thermal curtain over the entrance to the room.

To create an effective warm air barrier, the main role is played by the force of the air flow over the heating elements . For the majority of the UK, a wind speed of 2-4 metres / second is characteristic. Thus accordingly, you need to choose an air barrier, which at the exit of the nozzle, the air speed should be at around 10 metres per second; and at the floor level, the air speed should be at least 2-4 metres per second for the over door heated air curtain to work correctly.

Commercial overhead door heaters

There are two main ways of heating a commercial overhead door heaters, the first and most common is an electrical powered unit. These tend to be three phased powered, although we do have options for single phase if your site only has that voltage available. 

There are no special differences in the design of an electric overhead door heater, as apposed to a water heated heater, only that they use an electrical coiled heat exchanger for effective heating of the air flow. These days , the most effective and reliable electric heat exchangers are  know as “PTC electric coils” – which are a modern and safe solution for an electric commercial over door  or overhead heater – The benefits over the older  technology for the electrical heater elements of these commercial door heaters that used heating wires or spirals are – 

  • Larger heat exchange surface (surface of contact of the heat exchanger with heated air)
  • Lack of voltage on the surface of the electric coil
  • Fully automatic heat control depending on air flow
  • Significantly lower coil temperature in comparison to the older type of electric heaters (e.g. heating wires or spirals)
  • Complete elimination of the risk of system overheating due to self-regulating heating modules (heat capacity automatically reduces when air flow goes down)
  • And last, but not least – Lower energy consumption 
commercial overhead door heaters;commercial over door heaters;

Commercial overhead door heaters from Flexiheat UK

The Pro’s and Con’s of Electric Commercial Over Door Heaters – 


  • Easy of Installation – just extend the electric cable to the electric over door heaters installation site.
  • Ease of maintenance – the heat exchanger is easy to get at for preventive maintenance such as cleaning the heat exchanger.


  • High operating costs – the electric heater will work for heating mainly in the daytime, when the most expensive electrical tariffs are in effect

  • Electric horizontal overhead air curtain heaters spend the first couple of minutes getting up to heating temperature. 

For the full details and range of our electric over door heaters, please click here

Doorway Heaters – Water Heated

The second most popular option is a hot water heated overhead air curtain heater, these are also referred to as hydronic over door heaters or air curtains. They obviously require a hot water source, usually a wet central heating system, that has the required capacity to accommodate the heat output requirements of the units. 

Their operating principle is as follows – The heat medium- in this case the hot water from a central heating system is supplied to the heat exchanger, the cool, air passes over the heat exchanger, and heats up, before entering the fan assembly. The fan then pushes the warm air out at high speed, and pushes it out of the commercial over door heater towards the floor of the door or entrance of the commercial building, and creates an air barrier from above the door. Water heated overhead heaters usually have a heat exchanger with a large surface area to achieve the required heat output required.

Commercial water heated over door heaters; water heated overhead heaters; commercial air curtain heaters;

Commercial water heated over door heaters – you can see the pipework to the right of the overhead heater.

If you have a wet central heating system at your commercial premises, and have the kW capacity in the heating system to use a water heated commercial over the door heater, then they are the best doorway heaters for your site.

Pros: Normally cheaper operating costs in comparison to electric heated over the door heaters.

Cons: Installation costs and complexity – you have pipework to run.

More maintenance- Dosing and venting of the heating system is required. Potential leaks etc.

For the full details and range of our water heated over door heaters, please click here

Commercial over door heater

Commercial over door heaters deliver a continuous wall of warm heated air from the bottom to the top of a doorway or entrance. They have a high air flow rate and are designed to create an invisible air barrier all the way down over a door or entrance. This air barrier separates the air between the two environments of different temperatures. They are widely used at commercial entrances that are more often open than closed.

So what information do we require to select the appropriate over door heater for you ? Basically 2 things – 

  1. What is your door width and height ?
  2. Do you require an electric heated or water heated over door heater ?

Also what can often be handy is a few pictures of the door that requires the heater, to ensure that we know the aesthetics and also to know that the heaters have the correct clearances required and will fit. 

Commercial overdoor heaters

Should you require anymore assistance or information on our Commercial over door heaters / Commercial overhead door heaters for sale in the UK and Ireland, please give us a call on 01202 822222 and our dedicated sales team will be happy to offer advice and assistance or just contact us by mail by clicking here


Electric Boilers for Heating

Electric Boilers for Heating

Electric Heating Boilers, work like all gas and oil boilers –  an electric boiler heats the water, which is then circulated via the flow and return pipework to either radiators or an underfloor heating system, and thus is often called a central heating boiler. The only difference between these boiler types is that it’s fuelled by electricity rather than gas or oil. They are a wet central heating system, just like an oil or gas boiler. Electric central heating boilers have high energy efficiency at 100% , which is higher than any gas boiler installation on the market – be they traditional gas boilers or condensing gas boilers heating systems.

Electric boilers tend to be particularly suited to properties that have no access to a gas supply – be it a mains gas supply or an lpg gas supply

What is an electric heating boiler?

An electric heating boiler generates heat using electric heating elements immersed in water. Electric boilers are highly efficient thanks to their efficiency – which is very close to 100%. They are easy to install in both new houses or flats and whilst renovating older properties, since they require only to be connected to the central heating system and the mains electricity supply. Unlike a gas or oil boiler, they do not produce any products of combustion and therefor no flue gases or fumes, meaning that there is no flue system to install, which results in lower installation costs. You can also lower your energy bills by taking advantage of low tariff electricity such as economy 7 rates.

electric boilers heating; electric boiler heating system;electric boiler underfloor heating;

Advantages and disadvantages of electric boilers for heating 

  • Installation: is quite easy and often very quick with regards to the time. These electric heating boilers can be wall mounted – (the most common) or floor standing, and are very compact – allowing you to place the electric boiler where you require.
  • Efficiency: these electrically powered heating boilers are an efficient system that has an efficiency close to 100% and allows you to heat your home or flat quickly.
  • Safety: there is no risk of an explosion or carbon monoxide leak which can result in carbon monoxide poisoning that can kill from waste gases.
  • Maintenance: an electric heating boiler requires little maintenance, and isn’t mandatory as compared to gas boilers in landlord properties – this ensures low maintenance costs if any.
  • Space saving electric heating system: these central heating boilers are compact, they are wall mounted and as opposed to an oil boiler, you will not need extra space to store the fuel for the boiler in a tank, eliminating the possibility of an oil spill or the smell associated with the oil storage tank.
  • Ecological heating solution? – if your using electricity generated form renewable energy, such as solar PV / Photovoltaic panels, wind turbines or wave/ water generated electric, that it can be said that you’re not contributing CO2 into the environment, and thus having a CO2 neutral heating system. The same can’t be said for a gas or oil boiler, as both of these are fossil fuels and emit CO2 into the environment.
  • Legislation changes – The current talk is of banning gas heating for new houses by 2025 more info here. Legislation may well force people to change their boilers to electric, whether they have a mains gas network supply or not.
  • The downside – The price of electricity/running costs : at present it’s more expensive than gas and fuel oil, whether it will be lower in relative terms in the future, due to the push for renewable energy- who knows?
  • Any professional heating engineer will be able to fit electric boilers normally in conjunction with an electrician – there’s nothing special about electric central heating boilers as a matter of fact they are easier to install  than a gas boiler for example, as there’s no flue pipes to install, and the lower emissions electric boilers can be placed or fitted in many more locations due to this fact than the average gas boiler.
  • Electric combi boilers are also available that will do the heating and hot water requirements as that what a combi boiler is designed to do- but in reality you need a 3 phase power supply to get useable electric combi boilers – we do have an electric combi boiler solution for single phase boilers /properties/or locations – and these are listed on our dedicated web page here –  electric combi boilers
  • Carbon footprint / carbon emissions can be eliminated or reduced if you are powering the electric boilers from renewable electric power supplies. Unlike gas boilers which produce carbon emissions
  • Running costs can be reduced as our electric boiler range have as standard weather compensation and optimization – built into the units – This can help reducing running cost by 20% as the electric boiler adapts it’s output to the prevailing weather conditions. 
  • Domestic hot water – you can produce hot water via an indirect hot water cylinder with our boilers.

Electric Boiler Heating Systems 

These electric boilers for heating are one of the simplest and most cost-effective solution for central heating. They also ideal for heating flats or houses where there are no or limited possibilities to route a chimney / flue pipe system, for example in buildings of historical value or stone constructed houses. Also, electric heating boilers, are a perfect solution for petrol station heating where only fire-resistant equipment should be used for safety reasons and requirements. They also suit holiday home heating and caravan boiler requirements very well too.

We do a full electric boiler range from 0.5 kW to 45 kW in heating output. These electric wet central heating boilers can be powered by single phase electricity up to 15 kW of output electric boiler , and from there on and up to 45 kW they require a three phase electric supply to the electric boiler. Full details on the range can be found on our dedicated product page here – Electric central heating boiler range

electric wet central heating boiler; electric boiler heating system; electric boiler underfloor heating

Electric wet central heating boilers from Flexiheat UK

Electric heating boilers for underfloor heating?

A question we often get asked is can you use an electric boiler for underfloor heating? The quick and simple answer is yes – Our range of electric heating boilers can heat the central heating water from Zero Centigrade all the way up to 80 Degrees Centigrade. Most underfloor heating system will have a flow temperature between 35-60°C, depending on the heat losses from the property or building. If the underfloor heating system operates with thermostatic mixing valves, then commonly they use 45°C temperature for screeded floors and 55°C for timber suspended and floating floors.

Electric central heating boiler systems – UK and Ireland

Should you require any further assistance with our electric central heating boiler systems / electric boilers for heating or any of our products, please click here to contact us via email or call us direct on 01202 822221