Zanussi ULTRA COMBI 35 Installation And Servicing page 36

33 GENERAL CHECKS
Make the following checks for correct operation in:
1. Fully open all DHW taps in turn and ensure that water flows
freely from them.
The display should read:
neon flashing
then:
neon steady when the burner lights.
2. Close all taps except the furthest one from the boiler and check
that the boiler is firing at maximum rate.
This is factory set to give a DHW temperature rise of
approximately 35 C at the flow rate stated on page 10 under
o
"operation".
3. Reduce the DHW draw-off rate to about 3 l/min (0.7gpm) and
check that the boiler modulates to deliver DHW at approximately
64 C.
o
4. Close the DHW tap and check that the main burner extinguishes.
The pump should overrun for 60 seconds and the display
sequence should read:
When the pump stops the display sequence should read:
Note. On systems in excess of 2 bar inlet pressure a water
pressure governor may be required to prevent water noise.
CENTRAL HEATING (CH)
& DOMESTIC HOT WATER (DHW) MODE.
1. Ensure that the CH external controls are calling for heat.
The display should read:
2. Fully open a DHW tap and check that hot water is delivered.
The display should read:
3. Gas Rate
Check the boiler gas rate when the boiler is at full DHW
output.
Check at the gas meter, with no other appliance in use.
Refer to Tables 2 & 3 for gas rates.
4. Close the DHW tap.
5. Set the central heating external controls to OFF. The burner
should go off and the pump continue to run for two minutes
The display should read:
6. Check the correct operation of the timer (if fitted) and all
other system controls. Operate each control separately and
check that the main burner responds.
36
INSTALLATION
WATER CIRCULATION SYSTEM
1. With the system COLD, check that the initial pressure is
correct to the system design requirements.
For pre-pressurised systems, this should be 1.0 bar.
2. With the system HOT, examine all water connections
for soundness. The system pressure will increase with
temperature rise but should not exceed 2.5 bar.
3. With the system still hot, turn off the gas, water and
electricity supplies to the boiler and drain down to complete
the flushing process.
Note: A flushing solution should be used during the flushing
procedure. Flushing solutions: Fernox Superfloc,
Sentinel X300 (new systems) or X400 (existing
systems). Refer to Frame 5.
4. Refill and vent the system, add inhibitor (see Frame 5),
clear all air locks and again check for water soundness.
5. Reset the system initial pressure to the design
requirement.
6. Balance the system. Refer to Frame 4.
7. Check the condensate drain for leaks and check that it is
discharging correctly.
8. Finally, set the controls to the User's requirements.
Note: The pump will operate briefly as a self-check once every
24 hours in the absence of any system demand.
Temperatures can be selected using the CH and DHW thermostats.
Knob Setting
Max
Min
Due to system variations and seasonal temperature
fluctuations DHW flow rates/temperature rise will vary, requiring
adjustment at the draw off tap : the lower the rate the higher the
temperature, and vice versa.
WATER TEMPERATURES
CH Flow Temp DHW Outlet Temp
o o
C ( F)
80 (176)
45 (113)
Installation and Servicing
o o
C ( F)
64 (147)
40 (104)