Airtherm can offer a fan dilution system to suit many appliances, from modern high efficiency condensing to gas blown and atmospheric boilers, however, the principal of diluting the products of combustion is to reduce the CO² content at the discharge to below 1%, CO 50ppm & NOx 5ppm (BS6644 / IGEUP/10) in line with current legislation. There are many design considerations that must be achieved, for instance, the correct sizing of the fan unit, dilution header, inlet and discharge plenum boxes, the location to adjacent buildings, openable windows, fresh air vent pipes and final discharge height. These can be found from the Clean Air Act memorandum, IGEUP/10 or BS6644, along with other certain provisions with respect to the final discharge height which is calculated based on the total kw input load of the plant. Good Practise: There are two methods that can be considered when designing the dilution system: Air is directly taken from the outside. Fresh air is taken from within the plant area. Generally, the favoured option is to take the air direct from the outside via a louvre situated on the external face of the building or above roof level. Further Considerations are: The inlet and discharge openings shall be, as far as possible, apart and located on the same building face to prevent external wind conditions affecting the overall operation and performance of the dilution system. Inter-connection section from the boiler to the main dilution header should be fitted with a manual volume control damper and, if deemed necessary by the appliance manufacture, allow a draft stabiliser device which will ensure a safe stable operation. Incorporate sufficient noise control. Suitable ductwork must be manufactured from stainless steel, with a requirement for a water-tight system when serving high efficiency condensing boilers. Where a condensing application is considered it is normal for pluming to take effect, however, a reduced external temperature will accelerate the process, nevertheless, this may lead to complaints if the discharge point is not positioned correctly. The dilution fan must incorporate a proving device normally a pressure switch, which interlocks with the boiler control. We offer a design, supply and installation service for flue dilution systems, and can offer a tailored-made package to site conditions and customer requirements Flues & Chimneys Our range of flue, chimney and exhaust systems range from 100mm to 1200mm diameter and have been specifically developed to provide an optimum solution for a varying range of commercial and industrial applications. Common systems include multi-functional fire rated or gas condensing exhausts; flues for use with naturally aspirated gas fired appliances fitted with draught diverters; twin wall insulated, multi-fuel chimney systems; twin wall systems for use with solid fuels; single wall flue systems for gas and oil products and gas and oil venting

1. Project Profile
Grange Farm Primary School,
Coventry
Consultant
■ IDP Midlands
Client
■ Mitie Build
Sector Front Entrance
■ Education
Products
■ MasterFlue System
Equipment
■ Mikrofill Ethos 90kw
Mikrofill Ethos Boilers
Application Airtherm Engineering Limited has recently completed a flue dilution
installation, working closely with the consultant and contractor at Grange
Farm Primary School, Coventry. The flue system selected for the project
■ High Efficiency Condensing needed to be aesthetically pleasing, discreet and blend in with the building
features, so a dilution system was chosen over a traditional system, which
the client was in total agreement. Airtherm provided design calculations for
the project using the latest iCalc sizing package, along with compressive
technical submission and Auto Cad drawings for approval prior to
manufacture and ordering of the equipment.
The flue system installed comprised of a 300mm diameter fully welded
dilution header, flatk Woods bifurcated epoxy coated fan, stainless steel
silencers, volume control regulators and supply and discharge louvres,
situated 2m from ground level to comply with Clean Air Act Memorandum.
0844 809 2509 | airtherm.co.uk | info@airtherm.co.uk

2. Product Solution
• Boilers: Mikrofill
• Model: Ethos 90kw
• Application: Flue Dilution System
• Operating mode: Wet
• Pressure: Negative / positive pressure
• Working pressure: 200 Pa (product will operate 1000pa max)
Flue Dilution System • Inner wall: 316L Stainless Steel fully welded
• Sealant : tri-lip 'o' type silicone ring
• Fuel type: Gas
Considerations:
Airtherm can offer a fan dilution system to suit many appliances, from modern high
efficiency condensing to gas blown and atmospheric boilers, however the principal of
diluting the products of combustion is to reduce the CO² content at the discharge to
below 1%, CO 50ppm & NOx 5ppm (BS6644 / IGEUP/10) in line with current
legislation.
There are many design considerations that must be achieved, for instance, the
correct sizing of the fan unit, dilution header, inlet and discharge plenum boxes, the
Typical Flue Dilution location to adjacent buildings, openable windows, fresh air vent pipes and final
discharge height. These can be found from the Clean Air Act memorandum,
IGEUP/10 or BS6644, along with other certain provisions with respect to the final
discharge height which is calculated based on the total kw input load of the plant.
Good Practise:
There are two methods that can be considered when designing the dilution system:
Contact Details:
Airtherm Engineering Ltd  Air is directly taken from the outside.
 Fresh air is taken from within the plant area.
Ventilation House
Pedmore
We offer a design, supply and installation service for flue dilution systems, and can
Stoubridge offer a tailored-made package to site conditions and customer requirements.
West Midlands
DY9 0DS
Tel: 0844 8092509
Fax: 01562 887312
0844 809 2509 | airtherm.co.uk | info@airtherm.co.uk