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c) The minimum height of the flue system further than 3 m from the highest point of the roof shall be
1000 mm above roof penetration;
d) No part of any building lies in or above a circular area described by a horizontal radius of 3 m about
the flue system exit.
8.3 Suitable Flue systems
Your zero clearance wood inbuilt will provide optimum efficiency and performance when connected to a
150 mm diameter flue.
8.4 The Relationship Between the Flue system and the House
Because the venting system is the engine that drives the wood heating system, it must have the right
characteristics. The signs of bad system design are cold backdrafting when there is no fire in the zero
clearance wood inbuilt, slow kindling of new fires, and smoke roll-out when the door is opened for loading.
8.4.1 Why the Flue system Should Penetrate the Highest Heated Space
When it is cold outside, the warm air in the house is buoyant so it tends to rise. This tendency of warm air
to rise creates a slight pressure difference in the house. Called 'stack effect', it produces a slightly negative
pressure low in the house (relative to outside) and a slightly positive pressure zone high in the house. If
there is no fire burning in a heater connected to a flue system that is shorter than the warm space inside
the house, the slight negative pressure low in the house will compete against the desired upward flow in
the flue system.
There are two reasons why the flue system
in the house at right will cold backdraft
when it is cold outside and there is no fire
burning in the zero clearance wood inbuilt.
First, the flue system runs up the outside
of the house, so the air in it is colder and
denser than the warm air in the house.
And second, the flue system is shorter
than the heated space of the house,
meaning the negative pressure low in the
house will pull outside air down the flue
system, through the zero clearance wood
inbuilt and into the room. Even the finest
zero clearance wood inbuilt will not work
well when connected to this flue system.
8.5 Required Supply of Combustion Air
The Stratford CF wood fireplaces requires to have a supply of combustion air from outdoors (fresh air intake
kit). Moreover, to protect against the risk of smoke spillage, a carbon monoxide (CO) detector/alarm is
required in the room in which the fireplace is installed. The CO detector will provide warning if for any
reason the wood fireplace fails to function correctly (see Section 6.3.2: Installing the Mandatory Fresh Air
intake Kit).
OPERATING & INSTALLATION INSTRUCTIONS FOR STRATFORD CF ZERO CLEARANCE WOOD HEATER
49
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