8
Woodtec Freestanding
Issue 01.1 05/17
Where the chimney is believed to have previously served an open fire installation, it is possible
that the higher flue gas temperature from the stove may loosen deposits that were previously
firmly adhered, with the consequent risk of flue blockage. It is therefore recommended that the
chimney be swept a second time within a month of regular use after installation.
If you have any doubts about the suitability of your chimney, consult your local dealer/stockist
or chimney specialist. If there is no existing chimney then either a solid fuel compatible
prefabricated block chimney or a twin-walled insulated stainless steel flue to BS 4543 can be
used. These chimneys must be fitted in accordance with the manufacturer’s instructions and
Building Regulations.
5.2.
Ventilation
Document J of the Building Regulations states that purpose provided ventilation is not required
in England and Wales unless the appliance nominal rated output is greater than 5kW. Over 5kW
5.5 cm
2
of ventilation (550mm
2
) is required for every kW output above 5. For example 6.5 kW
requires 8.25 cm
2
and 8 kW needs 16.5cm
2
. In any case, if difficulty in starting the fire or any
excessive fuming is experienced, ventilation must be put in place as required to eliminate these
flue problems. If a flue draught stabiliser is fitted then extra ventilation is required. See
Document J of the Building Regulations for detailed guidance especially in new build properties.
A specifically designed direct outside air connection may be used with these stoves to provide
appropriate levels of ventilation (significantly in excess of the above requirements) directly to
the stove and chimney as follows. NOTE: in order to register the installation with HETAS as of
early 2016 certain extra evaluation and checking is required if using an outside air connection. If
the direct air kit is used and no ADJ vent is installed then a direct registration with Building
Control may also be possible.
5.3.
Direct Outside Air Connection
These stoves are supplied with the facility of using a dedicated 100mm diameter direct
connection duct through a suitable route to the outside air. It can be connected to the rear of
the stove and should be fitted at the time of stove installation. Only the approved kit for these
stoves should be used. This is designed to supply all the necessary air for safe combustion and
operation of the stove – providing there is no depressurisation of the property by mechanical
or other types of ventilation, the flue, chimney and ventilation duct are working correctly, and
properly maintained clear of obstructions or leaks etc. The kit supplies all the primary,
secondary and tertiary air to the stove and also provides room ventilation in excess of the
Document J Building Regulations during re-fuelling via the air connection unit under the stove
and so subject to no depressurisation (as above) may be used where mechanical ventilation and
heat recovery (MVHR) units are used. Some additional instructions for installation are provided
with the dedicated kit supplied. NOTE: in order to register the installation with HETAS as of 2016
certain extra evaluation and checking is required if using an outside air connection. If the direct
air kit is used and no ADJ vent is installed then a direct registration with Building Control may
also be possible.
5.4.
Flue Draught
Typically a flue draught at the flue collar of minimum 2.2mm to a maximum 3.5mm water gauge
(22 to 35 Pascals) is required for satisfactory appliance performance. This relates to 12-25
Pascals at the tapping on EN13240/13229 test rigs. The flue draught should be checked under
fire at high output and, if it exceeds the recommended maximum, a draught stabiliser must be
fitted so that the rate of burning can be controlled to prevent over-firing.
5.5.
Connection to the Chimney
This appliance is not suitable for use in a shared flue.
