36
INSTALLATION
isar - Installation and Servicing
45
GENERAL CHECKS
44
INITIAL LIGHTING - continued
15. DOMESTIC HOT WATER
With the boiler firing, set the DHW thermostat knob (Y) to
maximum and fully open a DHW tap.
The boiler should continue to run and the LED display
should show status
.
16. Ensure that with the boiler operating the dynamic gas
pressure is able to obtain maximum output. Refer to Table
2.
N.B. The principle of the 1:1 gas valve ensures that the
isar HE range is able to deliver it’s full output at inlet
pressures down to 14mb. However if dynamic pressures
below 20mb are experienced ensure this is adequate for
ALL other gas appliances in the property.
IMPORTANT
The gas input to the burner is regulated by the gas valve
according to the air flow produced by the fan. It is NOT
user-adjustable. Any interference to sealed settings on
the gas valve will adversely affect operation and render
our warranty void.
DOMESTIC HOT WATER (DHW) MODE
1. With no call for CH or DHW the boiler should fire for a
short period to preheat the DHW plate heat exchanger.
The display should read
returning to
when the burner switches off.
Notes.
a. If no DHW is drawn off, the boiler will fire periodically
for a short time, to maintain the plate heat exchanger
temperature.
b. The DHW preheat operates 24 hours a day .
2. Fully open all DHW taps in turn and ensure that water flows
freely from them.
The display should read:
flashing then
when the burner lights.
Make the following checks for correct operation in:
3. 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
o
C at the flow rate stated on page 6 under
“operation”.
4. Reduce the DHW draw-off rate to about 3 l/min (0.7gpm)
and check that the boiler modulates to deliver DHW at
approximately 65
o
C.
5. Close the DHW tap and check that the main burner
extinguishes. The pump should overrun for a few 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.
17. Turn off the DHW tap.
18. Set the boiler on/off switch (A) to OFF.
19. Swing the control box into the servicing position. Refer to
Frame 51.
20. Remove the pressure gauge and tube. Tighten the sealing
screw in the pressure test point. Ensure a gas tight seal is
made.
21. Swing the control box back into its working position and
secure. Reconnect the ignition lead.
22. Refit the user control.
23. Fit the boiler front and bottom panels.
24. THE FASCIA
a. To remove the plastic fascia, prise off the retaining star
washers using a pair of pliers and place to one side.
b. Fill the remaining fixing holes with the white push in
caps provided.
25. Switch the boiler on again.
INSTALLATION
203319-3.pmd 27/03/2008, 08:1536
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