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Installation Considerations

Consideration for Design

When designing a System, allowance must be made so equipment can be serviced after installation and for the fitting of any spares which may be needed.

Also consideration for the flue arrangement so that they can be dismantled for servicing to take place (examples only).

The Standard Unit

The Standard Unit as described above is designed to be installed within an air handling unit or ductwork. Units with all external panels double skinned and insulated are available for self contained internal use with optional single skinned burner extension housing and weatherproofed for external installation. All external units are supplied with combustion air intake grille, hinged access door with lock and support stays and internal inspection lamp.

All units are supplied with a fully automatic start burner with sequence controls in accordance with CE approval and to the latest British Standards and Directives etc.

When a unit is required to be installed within a larger cabinet, perhaps to accommodate a higher volume air supply, adjustable air balancing plates can be installed to correct the balance of air between the unit and the by-pass area of the cabinet.

Units are available for horizontal, upwards or downwards discharge.

The Standard finish is in galvanised mild steel but can be supplied in an oven baked epoxy paint finish if required.

Process Heat Units

Process Heat Units are also available for normal space heating, low temperature air handling, or high temperature process heating. As high temperature process units are very specialised we would suggest contacting our Technical Sales Department before designing your system.

Overheat Protection

An overheat lockout manual reset thermostat will provide overheat safety protection against supply air fan failure or drastic reduction in air flow, resulting in the burner going to a hold-off condition and will not function again until the manual reset button has been pressed.

The combined overheat and fan control thermostat has the ability to allow the burner to give pre warm up to prevent cold air being dispersed when the unit is first started.

After a preset temperature has been reached it operates the supply air fan, thus discharging the warm air produced. When the heat is no longer required the burner is switched off but the supply air fan is allowed to continue to dissipate heat from the combustion chamber until the residual heat is removed. If this overheat facility is not required provision must be made to install a fan over-run timer to provide the same function. Overheat protection must be fitted.

Flue Pipe

All indirect fired heat units must have a flue. It is important to have a well designed flue system which should be a minimum of two metres in height and clear the apex of a roof by at least one metre. Whenever possible, horizontal runs of flue should be avoided. Supports should be provided for the flue and not rely on the unit for support. If the flue is more than fifty pounds in weight it should be self supporting. A condensation trap with a clean-out door should always be fitted at the base of the flue.

Down Draught

On external units it may be preferred for aesthetic reasons to fit a flue system which is as short as possible, however a minimum of one metre length should be fitted above the cabinet to reduce down draught problems.

If a down draught problem is anticipated, possibly due to the location of the flue terminal in relation to adjacent buildings or to prevalent site and landscape turbulence, an anti down draught cowl is recommended or in extreme cases the fitting of an l.D.

Fan dilution system. The fitting of a burner fan over-run timer is particularly recommended to prevent heat damage to the burner internals after shut-down.

Combustion Chamber / Heat Exchanger

The standard combustion chamber/heat exchanger consists of a stainless steel combustion chamber with a mild steel heat exchanger of multi-tube construction with a condensation trap and clean out door at either end.

If by location the heat unit is to utilise part or full fresh air and is situated near the coast, in salt air, high humidity or areas of chemical process, corrosion could affect the heat exchanger and internals of the unit when shut down. To avoid this, consideration should be made to install an inlet damper to prevent air being introduced into the module when shut down or fit a stainless heat exchanger at an extra cost.


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