Technical data

18
Natural gas supply
Appliances, when on a full output demand, will require
up to 3.1m
3
/hr of gas for the 440CDi and 4.4m
3
/hr of gas
for the 550CDi. The gas meter and supply pipes must be
capable of supplying this quantity of gas in addition to
the demand from any other appliance being served. It is
important that a gas supply pipe of at least 22mm diameter
is used. Under no circumstances should the size of the gas
supply pipe be less that of the appliance inlet connection.
The meter outlet should be capable of ensuring a nominal
pressure of 20mbar (8in wg) at the appliance. Particular
consideration should be given to the resistance to gas flow
created by elbows, bends etc. Pipework should be sized
to overcome this resistance, details of this are given in the
table below.
Liquid Petroleum Gas (LPG) supply
The appliances, when on a hot water or full output demand,
will require up to 2.3kg/hr of gas for the 440CDi and
3.2kg/hr of gas for the 550CDi. The gas tank or bottles
must be capable of supplying this quantity of gas at a
nominal pressure of 37mbar (14.8in wg) at the appliance.
The table below shows the LPG discharge through varying
lengths of pipe and the resistance to flow created by
elbows, bends etc. Pipework should be sized so as to
overcome this resistance.
Electricity supply
A 3amp fused three pin plug and unswitched shuttered
socket outlet (both complying with BS 1363) or preferably a
double pole isolator with a contact separation of 3mm in all
poles supplying the appliance should be used.
The appliance electrical circuits are also protected by an
internal 2.5amp fuse. The appliance must be earthed.
Mains cold water supply
Water Authority requirement
A direct mains cold water connection is permitted by Water
Authorities, however, it is recommended that reference
be made to local requirements. In the event of difficulty
contact the Worcester Technical Support Department.
Pipe sizing
Unless the mains pressure is low, a standard 22mm
diameter service pipe is normally suitable. A 22mm hot
water distribution pipe to the first branch is recommended
thereafter 15mm and/or 10mm to all draw off points.
Elbows or tees
Metres Feet
0.50 2
90º bends
Metres Feet
0.3 1
Approximate additional length to be allowed (natural gas)
Total length of Pipe diameter
gas supply pipe (m) (mm)
3 6 9 –
Gas 2.9 – – 15
discharge
8.7 5.8 4.6 22
rate m
3
/h
18.0 12.0 9.4 28
Elbows or tees
Metres Feet
0.6 2
90º bends
Metres Feet
0.3 1
Approximate additional length to be allowed (LPG)
Total length of Pipe diameter
gas supply pipe (m) (mm)
3 6 9 –
Gas discharge 8.0 5.2 4.2 22
rate m
3
/h 15.9 8.8 8.3 28