Air Supply; Room Or Internal Space Air Supply; Cupboard Or Compartment Air Supply; Effect Of An Extract Fan - Vaillant VCW 2O Instructions For Installation And Servicing

3.5 Air supPlY
Detailed recommendations for air supply are
given in BS 5440 : 2. The following notes are
intended to give general guidance.
3.5.1 Room or internal space air supply
The room or space in which the boiler is
located must have a permanent air vent' This
vent must be either direct to the outside air or to
an adiacent room or internal space which must
itself
'have
a permanent air vent of at least
i-n" same sizd direct to the outside air. The
minimum effective area of permanent air
vent(s) is specified below and is related to the
maximum rated heat input of the unit.
The balanced flued combi boiler, VCW-sine,
does not require the room or internal space to
have a oermanent air vent.
Appliance
cmz i n . 2
vcw20/1
vcw25/1
1 0 8
1 3 0
1 6
20
3.5.2 Cupboard or compartment air supply
Where the combi boiler is to be installed in a
cuoboard or compartment, permanent air vents
are required (for cooling purposes and in the
case 6f open flued appliances also for
combustion and flue dilution) in the cupboard or
compaftment at high and low level' These air
vents must either communicate with the room
or internal space or be direct to outside air.
The minimum etfective areas of the permanent
air vents required in the cupboard or
compartment are specified below (Tab. 1) and
are ielated to the niaximum rated heat input of
the unit.
Pos. of
air vents
Air vent areas
Airfrom room or
internal space
cmz
,
(inr)
Airdirectfrom
outside
cm2
I
(inr)
High
Level
vcw20/1
vcw25/1
VCW-sine
280
320
235
{42)
(50)
(36,5)
140
1 6 0
120
(21)
(25)
( 1 8 , 5 )
LOW
Level
vcw20/1
vcw25i1
VCW-sine
560
640
,235
(84)
(1 00)
(36,5)
280
320
120
(42)
(50)
( 1 8 , 5 )
T a b . 1
Note: Both air vents must communicate with
the same room or internal space or must
be both on the same wall to the outside
air.
Where cupboard or compartment air vents
communichte with the room or internal space
the room or internal space must itself have a
permanent air vent(s) as specified in 3.5.1.
3.5.3 Effect of an extract fan
lf there is anv tvpe of extract fan fitted in the
oremises there i6 the possibility that if adequate
iir inlet area from outside is not provided
ipittag" of the products from the open flued
combi boilers flue could occur when the extract
fan is in operation. Where such installations
occur a spiilage test as detailed in BS 5440.: 1
must be carried out and any necessary actlon
taken.
3.6 Water circulation system
Detailed recommendations for the water
circulation system are given in BS 5376 :2' BS
5449 :1 (Jor small bore and micro bore central
heatinq svstems) and CP 342- the following
notes ire of particular importance. Pipework
not forming pbrt ot the useful heating surface
should belnsulated to help prevent heat loss
and possible freezing, particularly where pipes
6
are run through roof spaces and ventilated
underfloor sPaces.
Draininq taps must be located in accessible
oosition-s which permit the draining of the whole
svstem including the combi heater and the hot
water system. Dlaining taps should be at least
1/2 in. nominal size and be in accordance with
BS 2879.