Doc No. 700015 Page 9 of 36
1.7 Ventilation
Requirements
AmbiRad VSX tube heaters can be operated as
flued or unflued appliances in accordance with
the relevant national requirements in the
country of installation.
1.7.1 Unflued Radiant Heater
Radiant tube heaters can be operated as
unflued appliances so that the concentration of
Carbon Dioxide (CO
2
) at positions where the air
will be inhaled does not exceed 0.28%. BS EN
13410 is a guide to achieving this requirement.
If the building air change rate exceeds 1.5 per
hour or if the heat input is less than 5W/m³, no
additional ventilation is required.
In addition to the ventilation requirements,
consideration needs to be given to the
possibility of condensation forming on cold
surfaces.
It should be noted that the clearance distance
around the burner increases when the unit is
operated unflued (see section 1.5). It should be
ensured that the combustion gases do not
impinge on any combustible materials.
Mechanical Ventilation
Mechanical ventilation must be rated at
minimum
10m³/h
per
kW
input
using
appropriately sized fans and interlocked with
heaters.
Natural Ventilation
BS EN 13410 should be used to size air vents
to provide adequate ventilation, an example of
this calculation is given below:
Site Details:
20°c Internal Operating Temperature
0°c Outside Air Temperature
5m between high and low level vents
Following the sizing procedure in BS EN 13410
gives an air exit velocity of 1.6m/s. This
equates to a free area vent at both high level
and low level of 17.36cm²/kW free area.
1.7.2 Flued Radiant Heater
In buildings having an air change rate of less
than 0.5 per hour, additional mechanical or
natural ventilation is required. For detailed
information, please see BS6896 section
5.2.2.2.1
Mechanical Ventilation
Mechanical ventilation must be installed to
meet a minimum of 0.5 air changes per hour
using appropriately sized fans and interlocked
with the heaters.
Natural Ventilation
Low level ventilation openings with a free area
of at least 2cm²/kW shall be provided. See
section 5.2.2.2.2.1.
1.8 Flue and Combustion Air Inlet
- Options
Dependent on the type of burner fitted to your
heater it is possible to have configurations of
flue and combustion air inlet options to those
shown overleaf:
• Option 1
For flued products of combustion and no
ducted air please refer to Figure 6.a.
• Option 2
For ducted air and products of combustion to
ventilated area please refer to Figure 6.b.
• Option 3
For flued products of combustion and ducted
air via concentric pipe please refer to Figure
6.c.
1.8.1 Important Information
1.8.1.1 Option 1 and 2
A suitable flue system complying with EN1856-1
(type T250 N1 D Vm L11040 O50) should be
used. Flue size 125mm diameter twin wall.
Flue systems can run either vertically or
horizontally up to a
maximum length of 9.5m
(including up to 2 x 90° bends plus the terminal).
The minimum flue length shall be 1m.
The flue system
must be terminated in a
vertical position
and in accordance with the
British Standard Code of Practice BS 5440: Part
1 - Installation and maintenance of flues and
ventilation for gas appliances of rated input not
exceeding 70kW net (1st, 2nd and 3rd family
gases), and the flue system manufacturers
instructions as supplied with the flue.
1.8.1.2 Option 3
A suitable flue system complying with EN1865-1
(type T200 P1 W V2 L50050 O00) should be
used. Flue size 100mm diameter single wall.
The
maximum flue length
shall be 9.0m
(including up to 2 x 90° bends plus the terminal).
The minimum flue length shall be 1m.
