Domestic Hot Water - Excel HE C24 User Manual

4 SYSTEM REQUIREMENTS - CH (continued) and Hot Water
b. Where access to a 'make-up' vessel would be difficult, by
pre-pressurisation of the system.
The maximum cold water capacity of the system should
not exceed 143 litres, if not pressurized. However, if the
system is to be pressurized, the efficiency of the
expansion vessel will be reduced and a larger vessel (or
smaller system volume) may be necessary. If the
capacity of the vessel is not considered sufficient for this,
or for any other reason, an additional vessel MUST be
installed on the return to the boiler.
Guidance on vessel sizing is given in Frame 3.
5. Filling. The system may be filled by the following method:
Through a temporary hose connection from a 'draw-off'
a.
tap, supplied from a service pipe under mains pressure.
Where the mains pressure is excessive a pressure
reducing valve must be used to facilitate filling.
When installing the filling device it must be connected as
shown below, to fully comply with the water regulations.
This may involve the fitting of an additional WRAS
approved isolator valve to the mains supply.
i. Thoroughly flush out the whole system with cold
water.
ii. Fill and vent the system until the pressure gauge
registers 1.5 bar and examine for leaks.
iii. Check the operation of the safety valve by raising the
water pressure until the valve lifts. This should occur
within 0.3 bar of the preset lift pressure.
iv. Release water from the system until the minimum
system design pressure is reached: 1.0 bar if the
system is to be pre-pressurised.

DOMESTIC HOT WATER

1. The domestic hot water service must be in accordance with
BS 5546 and BS 6700.
2. Refer to Table 1 for minimum and maximum working
pressures.
3. The boilers are suitable for connection to most types of
washing machine and dishwasher appliances.
4. When connecting to suitable showers, ensure that:
a. The cold inlet to the boiler is fitted with an approved anti-
vacuum or syphon non-return valve.
5 SYSTEM BALANCING
The boiler does not need a bypass.
BALANCING
1. Set the programmer to ON.
Close the manual or thermostatic valves on all radiators,
leaving the twin lockshield valves (on the radiators
referred to above) in the OPEN position.
Turn up the room thermostat and adjust these lockshield
valves to give boiler flow and return temperatures not
o
more than 20 C apart.
These valves should now be left as set.
excel HE -
Installation and Servicing
GENERAL
Water Flow Rate and Pressure Loss
Max CH Output
Water flow rate
(gal/min)
Temp. Differential
Head available for m.w.g.
system pump.
CH Return
Ecl 6053
b. Hot and cold water supplies to the shower are of equal
pressure.
5. Hard Water Areas
Where the water hardness exceeds 200mg/litre, it is
recommended that a proprietary scale reducing device is
fitted into the boiler cold supply within the requirements of
the local water company.
IMPORTANT
Provision MUST be made to accommodate the expansion of
DHW contained within the appliance, if a non-return valve is
fitted to the DHW inlet.
2. Open all manual or thermostatic radiator valves
and adjust the lockshield valves on the remaining
radiators, to give around 20
each radiator.
3. Adjust the room thermostat and programmer to
NORMAL settings.
kW 23.4 28 32
(Btu/h) (80,000) (95,500) (109,000)
l/sec 0.28 0.33 0.38
(3.7) (4.4) (5.0)
o
C 20 20 20
o
( F) (36) (36) (36)
3.3 1.5 1.1
(ft.w.g.) (10.8) (4.9) (3.6)
Mains
water supply
Hose unions
Additional
stop valve
Temporary hose
(disconnect after filling) Double check valve
assembly
(
note direction of flow
o
C temperature drop at
)
11