Electric System Boiler – Electric Wet Heating Systems

What is an electric system boiler? – In contrast to a conventional electric boiler, which just contains a heat exchanger or chamber, a system boiler incorporates an expansion vessel as well as a circulating pump within the boiler. So, you have all the required components for a sealed wet heating system, also known as an unvented heating system.

Because of the way that an electric boiler system is constructed, there is no requirement for a feed and expansion system in the roof area or circulating pumps exterior to the electric boiler.

The fundamental difference between a system boiler and a regular boiler is how it is constructed.

Types of electric boilers

The earliest boilers ever developed for central heating systems were regular boilers, often known as traditional, conventional, or heat-only boilers.

Due to the low system pressure required by these older types of boilers, they are often supplied via a feed and expansion cistern in the attic, which is known as an open-vent heating system.

With a system boiler, installation is also quicker, simpler, and more efficient thanks to the built-in components, i.e., the heating expansion vessel and a pump.

The boiler’s compact design makes it excellent for heating applications when space is limited, as having the pump and expansion vessel within the boiler casing will eliminate unnecessary external plumbing that would be required if these items were separate components.

The last type of electric boilers are electric combi boilers, which do heating and domestic hot water on demand and these are detailed on this webpage – electric combi boilers

System boilers: electric

Electric system boilers for a wet central heating system are by far the most popular electric central heating boilers, just like they are for gas and oil boilers these days. As sealed heating systems offer many benefits to the customer.

No feed and expansion tanks that must be cleaned on a regular basis; no letting oxygen into the heating system water, which will promote corrosion. To prevent freezing, the pipes from the tank position to the boiler will need to be insulated when using an open vented central heating system.

A central heating electric boiler provides heat for a building

Electric boilers are an energy-efficient alternative to gas or oil boilers for home heating, as an electric central heating boiler has 100% energy efficiency for the immersion heater or heaters . A gas or oil boiler, even a condensing gas boiler, is 90–91% efficient at full condensation efficiency.

Electric boilers

Electric boilers work in a very similar way to gas and oil boilers in that they produce heat via immersion heaters, that is imparted into the hot water of the heating system, providing central heating via radiators or underfloor heating systems for small properties or larger homes.

Our Full Range of System Boilers

First, our touch-screen range of electric system boilers. This range of electric boilers has a fully touch-screen controller (like a mobile phone screen) and can also be controlled by a thermostat, programmer, or suitable “OpenTherm” compatible controller such as your Nest or Hive controllers, which allows you to control the system boiler via the controller or a mobile phone, so you can control your heating form anywhere in the world if you have Wi-Fi and an internet connection.

Touch screen range of electric hydronic boilers

These electric system boilers have the lowest power steps on the UK and Irish markets; for example, the FHEL5, which has a maximum output of 4.5kW, has 500 watt or 0.5 kW power increments or steps, which means the boiler will modulate up and down from 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, or 4.5kW, which ensures maximum efficiency by closely matching the central heating and domestic hot water requirements when using an indirect hot water cylinder.

Users can set the maximum output of the electric boiler to one of the power output levels, and the boiler will modulate up and down to that set level. E.g., the FHEL 5 can be set to 3.5 kw maximum output, and the boiler will ramp up and down to that kW output point.

The FHEL9 modulates up and down the power steps in 1 kW increments, thus 1, 2, 3, 4, 5, 6, 7, 8, or 9 kW outputs. The same applies as above, and this applies to all of this electric boiler range.

And finally, the FHEL14, which has a maximum output of 13.5 kW, modulates up and down the power steps in 1.5 kW increments, thus 1.5, 3, 4.5, 6, 7.5, 9, 10.5, 12, or 13.5 kW. The same applies to the boiler, which can be set to a particular desired output kW value and will ramp up and down to this value.

Touch series electric boilers for underfloor heating or radiators central heating – can be powered by either a single phase or three phase electrical supply.

Next is our standard series of electric system boilers:

Electric heating boiler from Flexiheat UK – Standard Series – From 2.5kW to 45kW Output

These electric boilers still have a touch control panel, but it’s a partial one that’s still easy and intuitive to use.

Electric boilers standard series from Flexiheat UK

Please note the following:

• After 15 kW, i.e., our 22.5 kW to 45 kW electric boilers, require an electrical three phase supply -3 Phase 400 volts, 50 Hz.

• The 30 kW and larger size electric boilers—we physically don’t have the space within the boiler casing to fit an expansion vessel, but come with the pump integral to the boiler, so you have to fit an expansion vessel external to the boiler (by others) to complete the sealed system and make them system boilers.

Electric Central Heating Boilers – Standard Series- Technical data HVAC  – Flexiheat UK

The 7.5kW to 22.5kW electric system boilers modulate in 2.5kW power steps.

• The FHEL8 has only 3 power steps on this unit, and the output can be set to either 2.5, 5 or 7.5 kW. Use the FHEL9; it’s a much better boiler.

• The FHEL15 Electric Boiler’s outputs can be set to either 2.5, 5, 7.5, 10, 12.5, or 15 kW.

• The FHEL23 Electric Boiler’s output can be set to either 2.5, 5, 7.5, 10, 12.5, 15, 17.5, 20, or 22.5 kW.

The 30kW and above jump in either 2.5kW or 5kW power steps.

FHEL30 – 30kw Electric Boiler: Output can be set to either 5,7.5,10,15,17.5,20,25,27.5 or 30kW.

FHEL38 – 38kw Electric Boiler: Output can be set to either 5, 10, 12, 5, 17.5, 22.5, 25, 30, 35, or 37.5 kW.

FHEL45 – 45kW Electric Boiler: Output can be set to either 5, 10, 15, 20, 25, 30, 35, 40, or 45 kW.

Download the Flexiheat Brochure For Electric System Boilers

Central heating with sustainable energy

When the electricity supplying your electric system boiler comes from renewable energy sources such as wind turbines, solar PV systems, or wave or water generated electricity systems, you are eliminating your carbon emissions, or at least reducing your carbon footprint, as well as reducing your running costs for your heating and hot water if you generate this electricity yourself.

Are electric boilers efficient compared to a gas boiler?

Yes, electric boilers achieve 100% efficiency by directly converting all the electricity that powers the heating element or elements into heating energy. Sometimes people refer to the overall efficiency as 99.9%, as the control panel of the boiler uses a minute amount of electricity.

A gas condensing boiler efficiency rate can reach up to 90–91% at full condensation (80% from fuel burning and 11% from flue gas condensation) when run at very low return temperatures.

Three phase electricity supply

When you have a three phase electric supply, you can install larger kW output electric boilers, as you have amps available in the electricity to power the electric boiler. We can go all the way up to 45 kW of heating element output.

Alternatives to gas boilers

Electric central heating boilers, especially electric system boilers, are a great replacement for traditional gas boilers, whether it be as a replacement or for a new installation. The benefits are:

• No combustion takes place in an electric boiler; thus, no flue system is required with an electric boiler to flue the products of combustion that gas boilers installed produce.

• A gas boiler has to be placed in certain locations, often to comply with flue system regulations—often on a wall that has external access so the flue can go straight out the wall—but with an electric boiler, you can locate them pretty much anywhere you want.

• No gas supply means there is no chance of gas leaks.

• There is no risk of carbon dioxide poisoning with an electric boiler installation.

• Carbon emissions: gas boilers produce CO2 as well as NOx as they use fossil fuel.

• If you use electricity to power your electric system boilers with renewable sources such as solar PV, wind turbines, or just purchase electricity that is produced by renewable sources, then you can reduce your carbon footprint or even have none at all for your central heating boiler.

• Quiet operation: electric boilers are virtually silent, i.e., you can’t hear the heating element or elements heating the hot water in an electric water heating system.

• Electric control panel: our electric boiler range has an inbuilt control panel that can be controlled by a thermostat or programmer. This can be an “OpenTherm” controller, such as a nest or hive type, allowing you to control these electric boilers from a phone, iPad, or computer as long as you have Wi-Fi or internet access.

What size of electric system boiler do you need?

We have a dedicated webpage on this which is here – what size electric boiler do I need ?

Who should consider an electric boiler?

Anyone who wants to have a wet central heating system but doesn’t have a gas supply or doesn’t want an oil tank at home. They are also a good alternative to a heat pump, in particular an air source heat pump in retrofit boiler replacement in wet central heating systems where the radiators, pipework, etc. were previously sized on the traditional flow and return temperatures of 82C/71C flow and return temperatures.

Most heat pump heating systems struggle to produce hot water over 55 °C, requiring the replacement of heat emitters, i.e., radiators, with units that can be up to four times larger and upsizing of pipework to accommodate the required flow rates for heating water. This issue also affects the demand for the domestic hot water tank demand, as domestic hot water needs to be stored at 60 °C to prevent legionella bacteria; thus, an immersion heating element or immersion heater is required to power the domestic hot water to this temperature.

Thus, in older properties, the additional cost of upgrading the wet heating system is prohibitive to many home owners, as the cost of materials and the cost of labour to fit all of the above will run into many thousands (even tens of thousands) of pounds.

This is where electric system boilers, when replacing a gas boiler for home heating and domestic hot water, are a suitable replacement with an easy install, as no heat emitters or pipework needs to be changed.

Electric system boilers for hot water and central heating

Electric system boilers can be installed anywhere in the house, are easy to operate, free from offensive fumes, do not need regular gas checks, do not require the installation of a flue, and have very few moving parts, minimizing the chances of malfunction. Get in contact with us for the best range of electric system boilers on the UK and Irish markets.

Destratification – What is it ?

Destratification- What is it ?

Destratification is the opposite of the natural process of thermal stratification in HVAC systems, which is the layering of different (usually increasing) air temperatures from floor to ceiling. Thermal stratification occurs when heated air rises to the ceiling or roof space or area because it is lighter than the colder air around it. Cooler air, on the other hand, descends to the floor level because it is heavier than the warmer air around it.

Its basic principles of physics really –as this surrounding cooler air falls to the floor level, and the hot air rises, this is the reverse of what we require when heating. We need to send that heat back down to where it is required, to heat the staff or customers of your business, thus reducing energy consumption and lower energy costs and this is where a destratification system solves this problem by using destratification fans.

Destratification technology can also be used on cooled air supplied by air conditioning systems by ensuring that the chilled air is properly mixing, circulated, and distributed equally throughout the building volume.

What is destratification, and how does stratification make it more difficult to keep the temperature constant?

Here we explore the issues of stratified air which is caused by hot air rising up to the roof space or ceiling level.

How does thermal stratification impact our living and working environments, and what is destratification?

This simple yet important law of nature can pose serious challenges to businesses trying to keep their buildings at consistent temperatures for their clients, employees, and inventory. Heating and cooling systems that are not efficient can be expensive and wasteful. Variations in air temperature can have a significant impact on both the working environment of personnel and the shopping experience. Some may be moaning about the heat in one location while others will be too cold, i.e., hot and cold spots.

In temperature-regulated storage facilities where consistent temperatures are necessary, temperature variations can also seriously affect the design of racking systems. This is particularly true in refrigerated storage facilities, where the cold temperatures are necessary to ensure the commodities’ quality and longevity. Many kinds of commodities’ “shelf life” might be impacted by excessively hot or cold storage conditions.

Thermal stratification

The development of “thermal stratification,” or naturally occurring thermodynamic layers, is the cause of the issue. Warm air rises naturally because it is lighter than cold air. To put it another way, cold air is heavier and denser than warm air. The warmer air is forced upward because the heavier object lowers. Thermal stratification is the result, which is a growing gradient of temperatures from the warmest at the top to the coldest at the bottom. It’s possible that many buildings lack high-quality ventilation systems because naturally, hotter layers develop at ceiling level while cooler layers remain at ground level. Thermal stratification can be more problematic in larger, more open spaces.

Open, high ceilings are common in commercial, industrial, and retail facilities, allowing tenants to arrange the space to best fit their needs. Mezzanine floors are prevalent. They are widely used to divide up employee workspaces and identify the various departments inside the company. The significant temperature variations between the various parts of the structure can make this type of space use problematic.

Temperature difference of the air

The “strata,” or ceiling temperature layers, of buildings taller than four metres differ from those at ground level, where standard thermostats are typically installed. Depending on the architecture and design, the temperature differential between the strata may be significant. A building is more prone to experience problems with thermal stratification the higher and more open it is.

Destratification fan systems can be advantageous in this situation. Effective and efficient heating and/or cooling of buildings calls for a tailored solution with a destratification fan or destratification fans ensuring air movement to eliminate air stratification.

Systems for destratification are intended to increase airflow in an area. Strong targeted destratification fans force the warmer air back down from the roof space to the floor area and prevent the temperature stratification by continuously mixing all the air in the building and reducing the temperature difference between the ceiling and floor. Because of this constant airflow recirculation, any extra heat produced by processes, people, or even solar gain ensures all air temperatures are blended equally and reduce the temperature gradient and lower energy costs for your building.

As a result, the temperature stays more consistent throughout. This lowers the energy consumed and thus the energy bills and makes it simpler to keep all your clients and staff at suitable working temperatures.

The benefits of thermal destratification systems

The benefits of thermal destratification systems are clear:

1.A 20% to 40% decrease in heating bills depending on ceiling heights – i.e., the higher the ceiling height, the larger energy savings.

2.Reduced carbon emissions / footprint – the less energy consumption the less carbon dioxide emissions occur

3. More comfortable environment for your customers or staff as you can maintain a even heating temperature within your building.

4.During the summer, destratification fans can also be employed to create cooling draughts of air.

Commercial benefits for business owners

Here are the issues an air temperature difference can present.

Building fabric heat losses will increase without destratification fans

The hotter air in the roof area influences how rapidly the structure loses heat. For example, the working areas temperature may be 20°C. On a chilly day with an outdoor temperature of -2°C, this would result in a temperature differential of 22°C between the working space and the outside. However, the air in the roof space will be roughly 24°C, resulting in a temperature differential of 26°C between the roof space and the outside air.

This is crucial because the temperature gradient influences the rate of heat loss. The greater the temperature differential between the air in the roof space and the outside air, the greater the rate of heat loss through the roof. Reduced heat loss ( and thus saving energy) via the roof covering can be minimised by lowering the temperature of the air in the roof space by using destratification fans to be more energy efficient.

For example, lowering the roof space temperature from 25°C to 21.5°C would result in a 14% reduction in heat loss through the roof surface. In many circumstances, optimising the circulation of warm air by destratification allows for the right temperature in the working space to be maintained using fewer warm air heaters, lowering both capital and operating expenses.

Losses via airflow infiltration

Another consideration is the influence of temperature gradients on the natural rate of ventilation, which occurs when air enters and exits the structure via leakage locations in the building fabric. It is generally known that part of the warm buoyant air ascending into the roof area will escape through high-level leakage spots. This will result in a slight negative pressure, which will attract additional chilly outside air into the structure via lower-level leakage locations. This low-level cold air entering the building lowers the temperature in the building, requiring the heating system to use more energy to achieve the desired temperature. Fabric heat losses and air penetration are especially problematic in older buildings with insufficient thermal insulation and numerous leakage spots.

Conclusion

Destratification fans, by mixing the air, eliminate stratified layers of hot air, successfully achieving temperature equilibrium across the entire space, and reduce energy consumption for heating systems.

Air stratification in buildings can be avoided by allowing the inside air to mix and move about. The temperature will be balanced by homogenising the air, or mixing it up and giving it all the same attributes. We call this process “destratification.”

Should you require more product information or get a project sizing on our destratification fans then please don’t hesitate to contact our sales team on 01202 822221 or use our email contact form via the contact tab above to message us.

120kW Boiler Gas Fired Condensing

Our gas fired 120kW boiler for heating commercial systems is available in natural gas or LPG gas (LPG biofuel is compatible as well).

This regular boiler can be used for space heating, central heating (radiators or underfloor heating), and domestic hot water production via accessories such as a plate heat exchanger or an indirect domestic hot water calorifier or cylinder.

They are a high-performance “A “rated efficiency , ErP-compliant condensing boiler and offer enhanced performance that exceeds the Part L building regulations for seasonal energy efficiency requirements. With low NOx Class 6, environmentally friendly emissions

Efficiency features: with a broad range of output modulation ratios of 20:1, automatic part load adjustment offers superb outputs down to 5.75 kw of heat output at 80/60 °C or 6.44 kW heat output at 50/30 °C, which leads to better heat load matching of the system, higher energy efficiencies, lower fuel consumption, and energy saving results.

This energy-efficient commercial boiler also has two stainless steel heat exchangers (2 x 60 kW) in one boiler, which ensures redundancy for your heating system; if one heat exchanger module fails, you still have  50% of your heat duty available. This enhanced performance feature can be vital for commercial customers on a site that can’t be without some heat.

120 kW wall hung gas condensing boilers

With the option of installing the boiler as a wall-to-wall solution or arranged on a suitable free-standing frame kit for floor-mounted installation, depending on site requirements.

Our 120kW gas fired condensing boiler on a free standing frame kit, with low loss header and plate heat exchanger for Domestic Hot Water production.

We can provide a solution for every commercial heating specification or commercial system, as we can cascade these high performance gas boilers up to 960 kW with automatic part load adjustment with an intelligent fault system that will monitor and report any faults on these commercial specification boilers.

Floor standing or wall hung gas commercial boilers from Flexiheat UK

120kW commercial wall hung gas boilers

As each boiler (heat exchanger) has its own flue non-return valve, you can service either boiler heat exchanger module without shutting the space heating system down.

Two heat exchangers – redundancy for the heating system – a wall to wall solution

Our energy-efficient condensing gas 120 kw boilers are fitted with fully modulating low NOx burners (Class 6 combustion levels) for lower environmental impact.

R1K120 gas condensing boiler output and energy efficiency figures—Part L building regulations

The latest changes to Part L of the Building Regulations, which went into effect on June 15, 2023, say that all new wet central heating systems should be sized for a maximum heating flow temperature of 55°C (previously, 75°C plus boiler flow temperature was allowed) and preferably lower if possible to get the most condensing heat transfer from condensing boilers, which results in high energy efficiencies.

Thus, our gas boiler will produce up to 125.67 kW heat output when the heating system flow and return temperatures are 50/30 °C.

The unit will also provide 114.64 kW at 80/60 °C heat output if you have a process heating application that is not covered in the Part “L” building regulations.

Full data is shown in the following:

This is detailed in our full manual, which can be downloaded here.

Manual for R1K120 Gas Condensing Boilers, Internal Version, Flexiheat UK

Should you require a larger output gas boiler (we do up to 240 kW in a single boiler and up to 980 kW in a cascade system), then we do a full range of gas condensing boilers for commercial use, which are listed here.

Gas commercial condensing boiler range

Condensing boiler specifications

• “A” ErP efficiency rating wall-hung boiler designed for commercial use or a very large home domestic central heating system and DHW for multiple bathrooms via a hot water cylinder or plate heat exchanger

• Low Class 6 NOx flue gas emissions make these more environmentally friendly as low carbon solutions today.

• Straightforward and easy install: all plumbing connections are at the bottom of the unit, saving installation costs.

• Energy efficient condensing boilers up to 105.8 %  at 50/30°C flow and return hot water temperature.

• Stainless steel heat exchanger with 28mm diameter water ways that ensure the boiler benefits from very low pressure drops, guarantees lower risks of clogging (more resistance to fouling up), greater thermal efficiency, and greater ease of cleaning.

• Can be arranged inline for larger output requirements to cover any commercial specification, but not back to back at present.

• These 120-kW gas-fired boilers have the identical outstanding efficiency and performance characteristics as their smaller domestic counterparts.

• Intelligent fault system: it will monitor system pressure, i.e., if the central heating system installation pressure is too low, etc.

System pressure

• Maximum heating operating system pressure = 3 bar
• Maximum heating operating system pressure = 0.3 bar

Controls

• An “Opentherm” thermostat controller, such as a “Hive” or “Nest” type, can control the boiler’s operation and temperature either locally or on the go using your phone, tablet, or computer. You can also use a basic thermostat; the choice is yours.
• BMS compatible with our 0–10 volt free contact kit

Boiler Fuel type

This 120kw high performance boiler can be powered by natural gas or LPG applications

Dimensions of this regular boiler: 120 kW Output for central heating and domestic hot water heating

This boiler has the following compact dimensions: 670 mm wide, 485 mm deep, and 642 mm high.

Connection details at the bottom of the unit: flow and return connections, gas connection, and condensate drain.

Free standing frame installation detail

Floor standing mounting kit

Boiler on our optional free-standing floor frame kit with low loss heating system header

120kW gas system boiler

Are these an 120kW gas system boiler? Yes, in that they have a pump (two pumps actually, i.e., one for each heat exchanger module), but at this size of system boiler, we can’t fit an heating expansion vessel within the boiler casing, so one needs to be fitted to the plumbing pipework external to the boiler to make the unit a full system boiler.

Flue options

Each heat exchanger module features its own flue exhaust connection. You can either individually flue each unit with an 80mm or 100mm flue up to 25 or 30 metres, respectively, either vertically or horizontally in range. However, if you use a split flue system, i.e., an 80mm flue diameter for the combustion air and 80mm for products of combustion, you can go up to 40 metres vertically or horizontally in range.

The last accessories option is a 100mm common flue header for the boiler.

Common flue header kit

Gas-fired 120 kW boilers

Should you require more product information, check stock, technical support, budget options, prices, or to order on our 120kw boiler in natural gas or LPG, then please don’t hesitate to contact our sales team on 01202 822221 or use our email contact form via the contact tab above to message us.

70kW boiler gas fired condensing

Our gas fired 70kW boiler is available in natural gas or for LPG gas fuel (LPG biofuel compatible to). They are a high-performance “A “rated efficiency , “ErP” compliant condensing boiler and offer enhanced performance that exceeds the Part L building regulations for seasonal energy efficiency requirements. With low NOx Class 6 environmentally friendly emissions.

This regular boiler can be used for space heating, central heating (radiators or underfloor heating), and domestic hot water production via a plate heat exchanger or indirect domestic hot water calorifier or cylinder.

Efficiency features: with a modulation ratio of 20:1, the automatic part load adjustment offers superb outputs down to 3.5 kw of heat output, which leads to better heat load matching of the system, lower fuel consumption, and you’ll save on energy costs.

This energy efficient commercial boiler also has two stainless steel heat exchangers in one boiler, which ensures redundancy for your heating system; if one heat exchanger module fails, you still have up to 50% of your heat duty available. This feature can be vital for commercial customers on a site that can’t be without some heat.

The unit comes with a 2-year warranty for parts , and the heat exchanger has a 5-year warranty if, as required by the building regulations, a dirt and air separator is fitted to protect the system, and the product is serviced annually.

70 kW wall-hung gas condensing boilers

With the option of installing the boiler as a wall-to-wall solution or arranged on a suitable free-standing frame kit for floor-mounted installation, depending on site requirements.

The 70kW gas fired condensing boiler mounted on a free-standing frame kit with low loss header and plate heat exchanger of domestic hot water production.

We can provide a solution for every commercial specification, as we can cascade these high performance gas boilers up to 960 kW with automatic part load adjustment if so required.

70kW commercial wall hung boilers

As each boiler (heat exchanger) has its own flue non-return valve, you can service either boiler heat exchanger module without shutting the space heating system down.

Our energy-efficient gas 70kw boilers are fitted with fully modulating low NOx burners (Class 6 combustion levels) for lower environmental impact.

Two heat exchangers for redundancy in one boiler casing with an output of 70 kW

R1K75 gas condensing boiler output and energy efficiency figures—Part L building regulations

The latest changes to Part L of the Building Regulations, which went into effect on June 15, 2023, say that all new wet central heating systems should be sized for a maximum heating flow temperature of 55°C (previously, 75°C plus boiler flow temperature was allowed), and preferably lower if possible to get the most condensing effect from boilers.

Thus, our gas boiler will produce up to 79.35 kW when the heating system flow and return temperatures are 50/30 °C.

The unit will also provide 72.83 kW at 80/60 °C if you have a process heating application that is not covered in the Part “L” building regulations.

Full data is shown in the following:

Output and energy efficiency figures for our R1K75

This is detailed in our full manual, which can be downloaded here.

Manual for R1K 75 Gas Condensing Boilers – Internal version Flexiheat UK

Should you require a larger output gas boiler (we do up to 240 kW in a single boiler and up to 980 kW in a cascade system, then we do a full range of gas condensing boilers, which are listed here.

Commercial gas condensing boiler range

Specifications

• “A” ErP efficiency rating wall-hung boiler designed for commercial use or a very large home domestic central heating systems and DHW for multiple bathrooms via a hot water cylinder.
• Low Class 6 NOx flue gas emissions making these more environmentally friendly.
• Straightforward and easy install: all plumbing connections are at the bottom of the unit saving installation costs.
• Energy efficient condensing boilers up to 105.8 % at 100% heat input at 50/30°C
• Stainless steel heat exchanger with 28mm diameter water ways that ensure the boiler benefits from very low pressure drops, guarantees lower risks of clogging (more resistance to fouling up), greater thermal efficiency, and greater ease of cleaning.
• Intelligent fault system: if the boiler has a fault, it will tell you exactly what has gone wrong, i.e., if the heating system installation pressure is too low, etc.
• Maximum heating operating system pressure = 3 bar
• Maximum heating operating system pressure = 0.3 bar
• An “Opentherm” thermostat controller, such as a “Hive” or “Nest” type, can control the boiler’s operation and temperature either locally or on the go using your phone, tablet, or computer. You can also use a basic thermostat; the choice is yours.
• BMS compatible with our 0–10 volt free contact kit

Dimensions of this regular boiler: 70 kW Output for central heating and domestic hot water heating

This boiler has the following compact dimensions: 670 mm wide, 495 mm deep, and 642 mm high.

A small compact energy efficient gas condensing boiler 70 kW with ErP “A” rated for central heating (radiators or underfloor heating) and domestic hot water via a calorifier.

Connection details at the bottom of the unit: flow and return connections, gas connection, and condensate drain.

Free standing frame installation detail

Floor standing mounting kit

Boiler on our floor free standing frame kit with low loss heating system header option

70kW gas system boiler

Are these an 70kW gas system boiler? Yes, in that they have a pump (two pumps actually, i.e., one for each heat exchanger module), but at this size of system boiler, we can’t fit an expansion vessel within the boiler casing, so one needs to be fitted to the plumbing pipework external to the boiler to make the unit a full system boiler.

Flue options

Each heat exchanger module features its own flue exhaust connection. You can either individually flue each unit with a co-axial flue (80mm/125mm) should you wish to go room-sealed up to 10 metres vertically or horizontally in range. However, if you use a split flue system, you can go up to 40 metres vertically or horizontally in range.

The last option is a common flue header for the boiler.

Common flue pipe header option

Gas fired 70 kW boilers

Should you require more product information, check stock, technical support, prices, or to order on our high performance 70kw boiler in natural gas or LPG, then please don’t hesitate to contact our sales team on 01202 822221 or use our email contact form via the contact tab above to message us. Follow our business on Facebook or Twitter if you’re interested in being informed of our latest recommend manufacturer product range items deal.

Buffer tank with coil or twin coils

A buffer tank with coil or coils is used to hydraulically separate a heat source or sources, in the event of a twin coil buffer tank, from the heating system’s hot water. This can be required for mechanical engineering reasons such as flow rate or temperature difference between the heating system and the heating source , which is often the case with heat pump heating systems, be they air source heat pumps or geothermal heating systems.

With a full range of buffer tanks from 260 litres in hot water storage volume all the way up to 5,000 litres of storage capacity, we have the volumes to satisfy any application or performance requirements for your inertia tank.

We do two ranges which will detail below

Why use a buffer with a coil ?

The coil acts as a heat exchanger, separating the hot water generated from a heat pump, boiler, or solar thermal fluid in the event of a solar thermal system from the hot heating water in the thermal storage tanks.

This can ensure that there are no problems with flow rates between the heated water from the heat source and the heating system, and also temperature differences, i.e., some solar system fluids can get up to 200 °C, whereas the storage tank temperature ratings are either 95 °C or 110 °C maximum. Thus, the use of a heat exchanger coil within the buffer tank is required.

The coils used are not a stainless steel coil , like those used in an indirect water heater that produces domestic hot water. We are not producing domestic hot water in a buffer tank with an intermediate heating coil to produce hot water for the heating system. The coils are made of steel, just like the thermal storage tanks.

Which means these buffer tanks must be used on a sealed heating system only, and the heating water must be treated with a corrosion inhibitor.

Domestic hot water production

If you want a Buffer tank with a stainless steel coil to produce domestic hot water, then these are called Thermal store hot water cylinders or Thermal store cylinders – and we go into more detail on this range here: https://www.flexiheatuk.com/product/thermal-store-cylinders/ as these are our units for instantaneous domestic hot water heating or production via a stainless steel coil within the thermal storage tank and are available in volumes from 500 litres of storage to 2000 litres in range or size.

Single heat exchanger models

The first range is the “G” range. These are rated

Maximum working pressure: Coil – 25 Bar – Tank 6 bar

Maximum working temperature: Coil – 200 ºC – Tank 110 ºC

The storage tank also has an immersion heater port, should you wish to install an immersion heater as a back up or top up heat source.

Technical data: The “G -IS” buffer tank range has larger tapping ports than the “G – IFS” buffer tank range, which has the standard 40mm (1-1/2″) See “EH” detail on the following:

G-IS and G-IFS Buffer tank with a single coil / heat exchanger technical detail

Larger Size Storage Tank

Thermal storage tanks with hot water storage volumes ranging from 1,500 to 5,000 litres with a single coil.

These buffer tanks are available with an inspection and clean out manhole that is 400mm in diameter and are designated the “ISB” version.

Or as the standard unit without which is designated the “IS” version.

Technical detail

The full detail on the above tanks can be found in the following brochure – pages 12 & 13

Buffer Tanks Brochure Flexiheat UK

Solar thermal heating systems

Some fluids in the solar system can be heated to 200 °C. If this is the case, you need to use our “G” or “MV” range. However, if your water or fluid temperature is less than 110 °C, then we have another buffer tank product with a single coil, and these are detailed here:

Twin coil buffer tanks

Twin coil or two heat exchanger buffer tanks are suitable for applications with two energy heating systems feeding the thermal storage tanks. For example, one coil or heat exchanger can be fed by a thermal solar system, which is usually the lower coil in the buffer tank. The second coil or heat exchanger, which is located in the upper part of the buffer tank, can be fed by heat generated from either a traditional gas or oil boiler or heat pump heating systems, which can be either ground source heat pumps or air source heat pumps.

Our Twin coil buffer tanks from 300 to 2,000 Litres in volume

These units are available from 300 to 2,000 litres in demand capacity.

The twin coil range has a heat exchanger maximum hot water temperature rating of 110 °C and 12 Bar pressure .

The buffer tank’s maximum temperature rating is 95 °C, and the pressure rating varies with the volume; please see the brochure for full details.

Flexiheat brochure for PPS2 Buffer tank with twin coils for sealed heating systems

Buffer tank with a coil or coils

Should you require more product information, availability, technical support, or prices on our complete range of buffer tanks with coil or coils then please don’t hesitate to get in touch. Contact our sales service team on 01202 822221 or use our email contact form via the contact tab above to message us.