Vaillant VCW 2O User guide

Instructions
forInstallation
andServicing
Vaillant
Combinedappliances
forheating
and
domestic
hotwater
VCW2Ol1T3W
GC-No.4704403
VCW2511T3
W
GC-No.47
04405
VCW-sine18T3W
GC-No.
47
O4401
Central
heating
Domestichotwater
Thisaoolianceshall
beinstalledin
accordance
withtherelevant
CodesofPracticebyBritishGasorbyanauthorized
installer
CORGI
member)
These instructions should be left near the gas meter when
the installation is completed.

1.
2.
J.
4.
7.
8.
q
10.
11.
Contents
lntroduction
Construction
of aPPliance
General
reouirements
lnstallation
of boiler
Watercirculation
system
Commissioning
and
testing
Assembling
Servicing
ofcombi
heater
Foult
finding
Shortlistof ports
Technical
data
2Construction
of
ApPliance
1lntrcduction
P4e The Vaillant csnbi boiler is a wall-rnqrrH
-2 natural draught open-flued (or in the case d
2 VCW-sine, room-sealed) boiler with buifr it
4 instantaneous
domestichotwater heater,
^l Output
ratingsareshown
in"Technical
Dda-.
;\ The boiler
is designed
for use in a sealedc
;; open vented system with pumped circuldin
,; ahd includes the instantaneoushot w&
46 sYSIem.
61 Circulating
pump,
expansion
vessel
(forseald
64 system only),terminal box, control and sdetf
devices
are
provided
with
theappliance.
Noteto Installers
ln hard water areas we recommend the d
supply
tothe applianceisvia a scalereducer.
-24
9
11
23
22
14
o
N
3
o
18
19
21
trin I
2

l Fkrcorinection
2 Down draught diverter
3 Sensorof overheat cut-off device
4 Mainheatexchanger
4a Combustion chamber
5 Mainhrmer
6 Gasgovernor
7 Flowswitch
8 Differential valve
9 DCsolenoid
10 Fbwthermometer
11 Pump
with
automaticairvent
12 Pressuregauge
\a- l airventpoints
Terminal
box
Switch
board
(main
switch,
heating
switch,domestichotwaterswitch)
Domesticheat
exchanger
Flowthermostat
Pressurereliefvalve
Servicecock
Gasservicecock
Overflow(optional extra)
Pushbuttonstart
Pushbuttonstop
Pilotburner
Piezounit
13
14
15
17
'18
19
20
21
22
23
24
25
o
o
'6
=
o

3General
requirements
3.1Related
documents
The installation
of thecombi
boiler
mustbe in
accordance
withthe relevant
requirements
of
theGasSafety
Begulations.),
building
regula-
tions, l.E.E.Regulations,
and the byelaws
ot
thelocal
WaterUndertaking.
Itshould
be in accordance
also
withany rele-
vant
requirements
of
thelocalauthority
and
the
relevani recommendations
of the following
BritishStandardCodesof Practice:
CP331 Installation
of pipes and metersfor
lowngas,
Part
3: Low Pressure installation
pipes.
BS5376 Selection
andinstallation
of
gas
space
heating
(1
.and
2.family
gases).
Part
2 Boilers of rated inPut not
exceeding
60kW.
BS5449 Central heating for domestic
oremrses.
Part
1 Forcedcirculation
hot water
syslems.
cP 342 Centralized
hotwater
suPPlY
Part
1 Individual
dwellings,
Part2 Buildings
other
than
dwellings.
BS5440 Flues and air suPPlY
for
appliances
of rated
inputnot
ding
60
kW
(1.
and
2.
familY
Part1
Flues
Part2AirsuPPlY.
BS5446:
1979
Installation
of gas hot
supplies
fordomestic
PurPoses
We
liketodrawyourattention
tothefactthd
connection
for the fillingor replenishingol a
sealed
primary
circuit
from
asupply
pipe
is
can
ditional
upona waterundertaking
seekingaa
obtaining
consentforarelaxation
otits
Byeh
3 and 8 (1)
from the Secretaryof State.
.) Gas
Safety
Regulation,
1972:
Itis
thelaw
thatall
gas
appliances
are
ins{d
by competent
persons
in accordance
witht:
above
regulations.
Failure
to installappliara ,
correctly
bould lead
to prosecution.Thisb L
your own interestand that of safetyto erisG
ihatthe
lawiscomplied
with.
3.2Location
3.2.1
Vcwqjle (8.F.APP|iance)
The location
dhosen
forthecombi
boiler
must
oermit the provisionsof a satisfactory
flue
ierminal. The location must also provide
adequate
space
forservicing
andair
circulation
aroundthe heater.
The combi boiler
may be
installed in any room, although particular
attention
is cjrawn
to the requirements
of the
l.E.E. Regulations
and, in Scotland,
the
electrical
provisions
of
thebuilding
regulations,
with respectto the installation
of the combi
boiler
ina room
containing
a bathorshower.
Where
the
installation
ofthe
combiboilerwill
be
inanunusual
location,
special
procedures
may
be necessary
and BS 5546and BS 5376 : 2
give
detailed
guidanceonthisaspect.
A compartment
used to enclose the combi
boiler must be designed and constructed
specifically
for this purpose.An existing
cup-
boardor iompartmentmay be usedprovided
that
itismodified
for
thepurpose.
Details of essential features of cupboardi
compartment
design
including
airing
cupboard
instdllations
are
given
inBS5376:2.
3.2.2
VCW(O.F.
APPliance)
The location
chosen
forthecombi
boiler
nrrsl
permit
the provision
of a satisfactory
fluead
bdequate
air supply.The location
mustfu
provide
adequate
spacefor servicing
ard *
circulation
around
theappliance.
Thecombi
boiler
must
notbeinstalled
ina
rqq
containing
a bathor shower.In addition,
it b
recommended
that
thecombi
boiler
should
rd
be
fitted
inabedroom.
Where
the
installationd
thecombi
boiler
willbeinanunusual
posilb\
special
procedures
maybenecessary
andBS
5'326
:2and
BS5546
give
detailed
guidanceot
this
aspect.
Acompartment
used
toenclosete
combi
boiler
must
bedesigned
andconstruec
specifically
for this purpose.An existingop-
bbard or iompartment may be used provided
that
itismodified
forthepurpose.
Details of essential features of cupboard
compartment
design
including
airing
cupboad
installations
are
given
inBS5376:2.
3.3
Gas
supply
3.3.1Service
pipes
The
local
gas
regionshould
beconsulted
atthe
installation
planning
stage
inorder
toestablish
4
theavailability
ofanadequate
supply
of
gas.
Anexisting
service
pipe
must
notbeused
wit>
out
prior
consultation
withthelocal
gasregiorl

3.3.2
Meters
Agas meteris
connected
tothe
service
pipe
by
the local gas region or a local gas region
contractor.
Anexisting metershouldbecheckedto
ensure
that it is capable of passing an additional
2.95 ms/h (106 CFH) before the VCW 20
(or
3.38mslh
(122
CFH)before
theVCW25or
2.47melh
(89
CFH)
before
theVCW-sine18)
is
installed.
3.3.3
lnstallationpipes
Installation
pipes
should
be
fitted
inaccordance
withCP
331
:3.
Pipework
from the meterto the combi boiler
must
beofaadequate
size.Donot
use
pipes
of
a smaller size than the combi boiler gas
connection.
The completeinstallation
must be testedfor
soundness
asdescribedintheabove
Code.
3.4Flue system
Detailed
recommendationsforfluing
are
given
inBS
5440
:1.Thefollowingnotes
are
intended
togivegeneral
guidance.
\=i= 3.4.1
VCW-sine
(B.F.
Appliance)
The boilermust be installedso that the flue
terminalis
exposed
totheexternal
air.
Terminationshouldbe on a clearexpanse
of
wall;
the terminal being preferably not less than
600mm(2 ft.)awayfromacorner,
arecessora
projecilon.
Donot installthe terminal:
a) Within300 mm (1 ft.) measured vertically
fromthebottomofanopenablewindow,
air
vent,
oranyother
ventilation
opening.
b) Within 300 mm (1 ft.) above adjacent
ground
level.
c) Within 600mm (2ft.)of anysurfacefacing
theterminal.
d) lmmediately beneatheavesora balcony.
Wherethe lowestpart of the termlnal
is less
than2 m(6,6 ft.)abovethelevel
ofany
ground,
balcony,flatroofor placetowhichpeoplehave
access, the terminal must by protected by a
guard
ofdurable
material.
Aterminal
protective
guard
isavailableasanoptionalextrawith
the
combiboiler.The airinleVproducts
outletduct
andtheterminaloftheboilermustnot
becloser
than 50 mm (2 in.) to combustiblematerial.
Detailed recommendations
on Drotection
of
combustible
material
are
given
inBS5440: 1.
3.4.2
VCW(O.F. Appliance)
Detailedrecommendationsforfluing
are
given
inBS5440:1.Thefollowingnotes
are
intended
togivegeneralguidance.
The crosssectionalareaofthefluefittedtothe
combiboilermustbe notless
thantheareaof
the flueoutletof the appliance.An adapteris
suppliedtoallowthefittingof125mm
steelflue
pipe
or125mmlight
asbestoscement
flue
pipe.
When fitting flue pipes a split socket
connector must be fitted to ensure easy
disconnection of the flue pipe (seepage13
fig.
16).
Fluepipesand fittings
shouldbe constructed
from
oneofthefollowingmaterials:
a) Asbestoscement,
b) Aluminium
orstainlesssteel,
c) Cast-iron acid-resistant vitreous enamel
lined.
lfdouble-walledflue
pipe
is
useditshouldbeof
atype acceptableto BritishGas.
lfachimney isusedit
preferably
shouldbeone
thatis composedof or linedwitha nonporous
acid-resistant material. (Chimneys lined
with salt-glazed earthenware pipes are
acceptableifthepipes
complywithBS65and
540:1.)Aflue
pipe
constructedfrom
oneofthe
materialsin
a)toc)above
should
formtheinitial
connection to lined chimneys. Where a
chimney
isto
beusedwhichisnotcomposed
of
or lined with a non-porous acid-resistant
materialitshouldbelinedwith
astainlesssteel
flexibleflue lineror any other liner
thatis of a
typeacceptabletoBritish
Gas.
Theinternal
dia-
meter
ofthelinermust
notbelessthan
shown
inthe technical
dataandthe number
ofjoints
mustbekepttoaminimum.lf
thefluelinerisnot
to be connected
directlyto the combi boiler
draught diveder a flue pipe which is
constructedfrom
oneofthematerialsin
a)
to
c)
aboveshould
form
theconnection
between
the
draughtdiverterand
flue
liner.
Before connectingthe combi boiler to, or
insertinga liner into, a flue that has been
previously
used,the flue must be thoroughly
sweptcleanofanysoot
and
loosematerial.lfa
register
plate,restrictor
plate,damperetc. is
fitted in the flue, it must be removedbefore
connectingthe combiboilerto, or inserting
a
linerinto,theflue.
The flueshouldterminate
in accordancewith
the relevant recommendations given in BS
5440:1,table4.
A terminal of a type that has been tested and
found satisfactory by British Gas should be
fitted
at
theflue
outlet.
The point of terminationmust not be within
600mm(2ft.)
ofanopenablewindow,
airvent
oranyotherventilation
opening. c

3.5
AirsupPlY
Detailed
recommendations
for air supplyare
givenin BS 5440 : 2.The following
notesare
intended
togivegeneral
guidance.
3.5.1
Room or internalspaceair supply
The room or space in which the boiler is
located
musthavea permanentairvent'This
vent
must
be
either
direct
tothe
outside
air
or
to
anadiacent
room
orinternal
space
which
must
itself
'have a permanent
air vent of at least
i-n" same sizd directto the outsideair. The
minimum effective area of permanent air
vent(s)
isspecified
below
andis related
tothe
maximum
rated
heat
input
oftheunit.
Thebalanced
flued
combi
boiler,
VCW-sine,
does
not
require
the
room
orinternal
space
to
haveaoermanent
air
vent.
Appliance cmz in.2
vcw20/1
vcw25/1 108
130 16
20
3.5.2
Cupboard or compartment air supply
Wherethe combiboiler
isto be installed
in a
cuoboard
or
compartment,
permanentair
vents
are required
(forcooling
purposesand in the
case 6f open flued appliances also for
combustion
and
fluedilution)
inthe
cupboard
or
compaftment
at highand low level'
Theseair
ventsmust
either
communicate
withthe room
orinternal
space
orbe
direct
tooutside
air.
Theminimum
etfective
areas
of
thepermanent
air vents required in the cupboard or
compartment
arespecified
below
(Tab.1)
and
areielated
totheniaximum
rated
heat
input
of
theunit.
Pos.
of
air
vents
Air
ventareas
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
160
120
(21)
(25)
(18,5)
LOW
Level vcw20/1
vcw25i1
VCW-sine
560
640
,235
(84)
(1
00)
(36,5)
280
320
120
(42)
(50)
(18,5)
Tab.1
Note: Bothair vents mustcommunicate
with
the
same
room
orinternal
space
ormust
beboth
onthesame
wall
totheoutside
air.
Where cupboard or compartmentair vents
communichte
withthe roomor internal
space
the roomor internal
spacemustitself
havea
permanentair
vent(s)
asspecified
in3.5.1.
3.5.3Effect of an extract fan
lf thereis anv tvpe of extract
fan fittedin the
oremises
there
i6
the
possibility
that
ifadequate
iir inlet area from outside is not provided
ipittag" of the productsfrom the open flued
combi
boilers
flue
could
occur
when
the
extract
fan is in operation.
Where such installations
occur
a spiilage
testasdetailed
inBS5440.:
1
mustbe carried
outand anynecessary
actlon
taken.
3.6Water circulation system
Detailed recommendations for the water
circulation
system
are
giveninBS
5376:2' BS
5449
:1 (Jor
small
bore
andmicro
bore
central
heatinq
svstems)
and CP 342-
the following
notes
ire of particularimportance.
Pipework
notforming
pbrtot the useful
heating
surface
should
belnsulatedto helppreventheatloss
andpossible
freezing,
particularly
where
pipes
6
are run through roof spaces and ventilated
underfloor
sPaces.
Draininq
taps must be locatedin accessible
oosition-s
which
permit
the
draining
of
the
whole
svstem
including
thecombi
heater
and
thehot
water
system.
Dlaining
taps
should
beatleast
1/2in.nominal
size
andbeinaccordance
with
BS2879.

F
,l
3.7Electricalsupply
Wiring external to the combi boiler must
be installed in accordancewith the l.E.E.
Regulations
and any local regulationswhich
apply.
The combi boileris supplied
for 22O/24OV,
50Hz.Fuseratingis
3A.
The
combiboilerhasto
beconnected
directto
themains
electricitysupply
usingtheinternal
terminal
box.
Forwiring
instructions
see
paragraph
4.7.
\-
4lnstallation
of
boiler
4.1General
The combiboiler
is to be wall-mountedand a
vertical
flatareaofwallisrequiredwhichmust
measureasshown
ontemplate-
This area does not include clearance for
installationand servicing.
lf the appliance is
fittedon awallofcombustible
material,
thewall
should be protected by a sheet of fireproof
material.
In addition.a minimumclearanceof 400 mm
Fig.3 All dimensions
inmm
(16 in.) must be availableat the frontof the
applianceto enable the combi boiler to be
servrceo.
Serviceclearanceof 150mm (6inches)
either
side
isreouired.
Forthe open fluetype appliancesVCW 2011
and25/1 anadditionalclearanceisrequiredfor
the flue. The combi boiler is supplied in
2 cartons,onecontaining the boiler,theother
the installation accessories. An additional
cartoncontainingtheterminal/duct
assembly
is
deliveredwiththebalancedfluedappliance.
E-
o
o
c
o6
>o-
FO.
(U
vcw20/1 vcw25/1
A1095mm 1161mm
B130mm
125
mmwithadaoter
15mm 22mm
D'l00mm 107mm
r1014mm 1080mm
KElectrical
mains
connection
weight 59kg 60kg
) Minimumdistance
requiredto
removeexpansionvessel.
Installationmayrequire
anotherdistance.
7

Fig.4 Alldimensions
in
mm
!
;
t
4.2Fluing
For
the
installation
of
the
flue
set
(wall
case)
ota
room sealed combi boiler, we reter-to rne
.!-o"t"i" -in.t"llation i
nstructions No' 806901
iniluded
with
every
flueset.
4.3Connection
A oeneral
viewof pipework
forgas andwater
coinectionis
given
in
fig.
5.
The following procedure describes the
installation.
Thewall
distance
(to
the
finished
wall)
ofpipe-
woit<
toigasandhbating
system
is.50
mmand
40mm
fordomestic
water
PiPework'
8
1. Compression union (flow of heating
svstem)
z. S-ervice
cock (flowof heatingsystem)
3. Domestic
hot
water
connection
4. Union
(gas)
5. Gasservicecock
6. Cold
water
connection
with
shut-off
valve
7. Service
cock
(return
ofheating
system)
8. Over
flow
(optional
extra)
9. Pressure
relief
valve
10. Compression union (return of heating
system)
11. Connection
support
23. Frame
ofappliance
(lower
connection)'

,,4
I

4.3.1
lnstallationaids
4.3.1.1
Openflued combi boiler
After
fixing
the
connecting
groupto
thewallput
the template
in position
ancl
mark
posltlons
oI
fixing
holes.
Thetype
offixing
used
willdepend
onthe
type
of
wall.
4.3.1.2
Room
sealed
combi
boiler
Afterinstallinq
the terminal/duct
assembly,
hano
the
tempi-ate
on
the
fixing
bolts
(1
)
and
drill
the5
holes
with
8
mm
(5/16
inches)
diameterto
fittheconnecting
group.
Use
thealternative
fixing
holes
where
necessary.
4.3.2
Domestic
coldandhotwatel
connection
- Flush out all loreign matterfrom the
supply pipe beforeconnecting
to the
connecting
grouP.
- Fit
thedomestic
mains
water
pipe
to the
riqht
hand
compression
union
(2)
and
the
h5t
water
pipe
to
the
lefthand
compression
union
(3).
lnhard
water
area
the
mainssupply
tounion
(2)
should
be
via
ascale
reducer'
- bhect domestic
water
system
forsound-
ness.
N.B.
Thecombi
boilerhas
amaximumworking
oressure
of 10 bar.lf water
pressure
bxceeds
thisa pressurereducing
valve
will
haveto
be
fitted
tocold
water
inlet.
10
I
I
**!**o
rl I ll
fl | )l
+1-
I

I
I
I
I
I
t
{33 Gonnectionof heatingsystem
Fledirtg
syslemflowandreturn
should
be in
2. rrtn copperpipe and connected
to the
cqrtecting
group
as
showninfig.
9.
Ftllheheatingsystem
andtestfor
soundness.
4.3.4Pressurereliefvalve
andoverflow
The
pressure
relief
valve,required
for
asealed
system,isincludedinto
the
connecting
group.
- Screw in the overflow (4) below the
pressure
reliefvalveinto
the
drainline.
(To
beavailableas
anoptional
extra.)
I4.4Fitting
theappliance
Closeservicecocks
(5),
unscrew
unionnuts
(6)
and take off the olive-shaped
plastic
plugS.
Refitunionnuts(6) withbrass'compr6ssi-on
rings
(7).
Closemainswater
service
cock
(8)
andunscrew
theunionnutF
(9). *-A-6

4.4.1
Openflued aPPliance
Unpack boilerfrom carton and remove side
oarieislas in
8.1'1.),
lint
arrestor
(asin8'2'2)
inO pait ing aidsas wellas plasticcaps.from
the ionneciions.Insert
the appliance
wltntne
connection
tubes downwards into the com-
oiession
unions
of
theservice
cocks
andhang
itontothebolts(1)
and
fasten
screws
(10)'
Fasten
compression
unions
(6)
and
union
nuts
ig),
using
thb
attached
washers
(1
1)'
4.4.2 Balanced f
lued aPPliance
Unoackboilerfrom carton and removeside
Janels
(as
in8.1.1
.)and
packing
aids
as
wellas
blastic
baps
fromthe connections.
Fittheflue
buct(20)
irtitn
tne2 sheet
metalscrews
(22)to
the t;le6copic duct (16) of the terminal/duct
assemblY.
Insert
theappliance
with
theconnection
tubes
downward
iirio
the compression
unions
of the
service
cocksand hangit on to the threaded
bolts
of thewall
case(1),
fig.14.Fasten
nuts,
compression
unions
(6,
fig.
13)and
union
nuts
is, iig. 13) using the attached washers
(11,fig.13). 20 21
1Fixing
bolts
16
Telescopic
duct
19,22Sheet
metal
screw
20Flue
duct
2'l Flue
bend
Fig.
14
12

a
45 Gcconnection
Frtthe
gas
servicecock
(5)
totheappliance.
Cleil out all foreign matter from the gas
s.Dpty pipe before connecting to the
servicecock!
Connect
the
gas
supply
pipe
tothe
servicecock
andtighten.
4.6
Flueconnection
(open
flued)
Insertflueintothedraughtdiverterafterfitting
theadapter
provided.
A split socketconnectormust be fitted to
ensure easy disconnectionof the flue to
simplify
removalofthemainheatexchanger.
21
. Flue
pipe
22. Draught diverter
22.aCollarotthedraughtdiverter
24. Adapter
25. Splitsocketconnector
4.7Electrical
connections
Vaillant
combiboilersarecompletelywired.ltis
onlynecessarytoconnectthe
electricalmains
andtheroomthermostat.
Connectto220/240v
50Hz.electricalsgpplyfused
3
A.
Warning!Thisappliancemust
beearthed.
Afterremovingtheterminal
boxcoverconnect
themainstotheterminal
(c)
oftheappliancein
the mannerindicated
below.A cardboard
label
showingthecorrectmainsconnection
to
theterminalsis in theterminal
box.Please
removebeforeconnecting.
Donotconnecttheelectricalsupplytothe
pump
terminals
(b).
Full wiring diagramsfor variouscontrol
schemesareshown
intig.21Io24.
a
F--i
tl
tl
tl
ri

4.7.1
Connection of the mains cable
As shown on the figuresthe live conductor
*nicn iscoloured
brown
must
beconnected
to
theterminal
marked
witha L on theappliance
inOto
tne
tetminal
marked
Lorcoloured
red
on
the Dluq.
The neutral
wirecoloured
bluemust
6eioni"ct"O to theterminal
marked
witha N
ontneaoptiance
and
tothe
terminal
marked
N
oi coioureO
blackon the plug'The earthwire
coloured
qreen
andyellow
must
beconnected
i" rn" otine two teiminals
markedO on the
"opiiin"" and
tothe
terminal
marked
wrth
anE
oi svmbolO or coloured
greenor greenano
vellowon the plug. lf no roomthermostat
or
iimer is installbd,-terminal
3 and 4 must be
linked.
a.Fuses
2A (delay
action).
b.
Terminals
for
pumpregulating'
i- Terminals
forhppliance
input
connections'
4.7.2
Connection of Vaillantroom
-- thermostat with clock (no' 394)
Connection
of room
thermostat
ismade
to the
terminiri ganO
4.ltis
recommended
to
install
a
Vaillant
room
thermostat
(RT)with
accelerating
resistance.The room thermostat must De
inJiiiteo on an inner
wallwhich is influenced
neiiner
Ov
current
of airnorbythesun,inthe
livinq
rooin.
During
theinstallation
oftheroom
therftostat
the
manufacturer's
indications
must
be followed.For the sake of economy and
iotfurt the Vaillant combi boiler should
be requlated by a room thermostat with
icceleiatingresiitance.
lftheroom
thermostat
isnotconnected,
tooperate
theheating
system
ior i"iting purposes'after
the installation,
the
,nit "an bi op6rated
byprovisionalapplication
oi a OriOge
between
ihe terminals
3 and 4'
Wfren tfrE room thermostatis wired in this
bridge
must
beremoved.
4.7.3
PumPcontrol
The pump may be controlled
in one of three
ways
(see
fig.
20):
Settinq
I(as suPPlied)
For-use with clock and room thermostat
systems.
Pumpis switched
off by clock or
roomthermostat.
Setting
ll
For"use with thermostaticradiator valve
svstems.
Pump is switched
off by clockor
o'as
valve
switih when
gasvalve closes'
seltting
ttl
Purip runs Permanently and is not
affectedbY
externalcontrols.
1 @@_a
..'\L*=
-j LEf,-l
@a
Fig.18
Sz
i
t
14

a
1,7, Thcrmostatic radiatorvalves
l$rere TRVs and a clock are used the
ilibfrirg side of the clock is connected
betreen teminals 3and4.
lYhere
noclockisusedawire bridge
mustbe
insertedbetween
lerminals3and4.
Setthe
pump
controltoposition ll.
VCW-Terminal
VAILLANT
Roomthermostat
VBT378 0
RANDALL
TimeSwitch 103
Do not link
terminal3 &6
N Mains
L Supply I
Fig.21 24OV/5OHz
VCW-Terminal SWITCHMASTER
300
Time
Switch
REMOVE
1)
LinkNand2
2)
Link
Land:4
N Mains
L Supply 3
O
VAILLANT
Roomthermostat
VRT378 024OVlsOHz
15

HORSTMANN 125
COFONET
Time Switch
Do
notlink
terminals
Land5!
N t.in"
L SuPPIY
J 2r0v/50H2 3 o
Fig.23
VAI
LLANT
Foomlhetmostat
vRT 378 l':-'
O
VAILLANT
Roomthermostat
VRT378 0
N Mains
L SUPPIY
+ 24ovl5oHz B
16

E
-9-
6=O
E;E
9p5
"9=i
E$s
a
lt^
ol
988-
x*'t
:oo
o(g
F
p
o
c
o
o
a?
o
o
3
o
'
o
=
;
",
1
EY
r()
AI
.st,
tt
E
o
o
o
c
'=
;
a
E
o
a
cl
c
3
.o
(,
CD
lo
(o
I
l
I
I
I
b
i
i

15
14
13
'12
11
10
9
I
7
6
5
70
71
73
54
5:l
21
n
23
24
25
77
26
30
2A
n
31
58
/-ffi 61
7A
46
1
32
Fig.26 0t[|il[[|ll
1 servicecock
3 flowswitch
4 thermostatic
element
5 gasinlet
6 automatic
valve
7 pilot
adiustment
screw
I switchbox/FFD
9 oushbuttonstart
10 pilot
valve
11 pushbutton
stop
12 thermo-magnet
13 micro
switch
14 thermo-couple
15 pilot
burner
16 sensor
ofoverheat
cut-off
device
17 main
heat
excnanger
18 air
venting
screw
19 expansionvesset
20 main
burner
21 gasgovernor ..
22 main
burner
adjustment
screw
i3 double-stage
main
burner
valve
24 venturi
25 differential
valve
26 DC
solenoid
i8 expansion
vessel
pressure
control
29 pump
18

i
i
-'_-43
N--.a.-:.*.
3?
:li"#3[?t!l3ll
o"'"""'ic
water
32 heating
circutr
39 main
switch
41 terminal
X3
tlo"o"*
rn"rto""'
$i[#s$:rrtt:"'
53 micro-switcn
t.
54 micro'switcn
ll
58 micro-switch
hot
water
59 water
sedlon .
60 cold
water
inlel
61 water
governor.
63 hot
water
outlel
3e
!3il'J3-:Y':ilvarcr
switch
70 electronic
control
71 NTC
resistor
1?
"1.1H,$3#3f;'ftL
*"*"'
78 systembypass
79 relaY
19

5Water
circulating
system
5.1
General
The combi boileris suitable
for use on most
minibore
andmicrobore
systems.
Itis recommended
to use
copper
tubing
to BS
2871
:1for water
carrying
PiPework.
The use of horizontal
pipe runs should be
avoided
wherever
possible
inorder
to prevent
air collecting
in the system.
lf horizontal
runs
areunavoidable
thepipes
should
riseupwards
towardsavent point.
For qeneral quidance reference should
be mide to ihe British Gas publication
- MATERIAL AND INSTALLATION
SPECIFICATIONS FOR DOMESTIC
CENTRAL
HEATING
AND
HOTWATER
-, B
and
to
BS5376:2and
BS5449
:1.
5.1.1
Single
PiPe
sYstem
Theheat
emitters
areinstalled
on a closed
circuit.
The
necessary
water
quantity
forevery
heat
emitter
(radiator)mustbe
ensured.
This
can be done
for instance
by using
suction
fittinos
in
thereturn
connection
of
theradiators.
The-radiator
sizes
shall
becalculated
onthe
basis
of temperature
distribution
around
the
circuit.
5.1.2
Two-pipesystem
Theradiators
are
installed
parallel
and
the
flow
temperature
therefore
is the same for every
radiator.
Typical
central
heating
installation
areshown
in
the
following
figures.
NOTE: 5.2to 5.5are applicable
to bothopen
andsealed
systems.
N.B. Theprimary
filling
point
may
beplaced
at
any
convenient
point
onthecircuit.
Fig.28
FillingPoint
Fig.29
20