Roberts Gorden DAT100 - Manual (Page 29)

SECTION 11: C OMMISSIONING
23
11.4.2 Commissioning the Gas Valves
All DualAir ® units are fitted with fully modulating
burner operation. The Honeywell automatic gas
valves are fitted with the Honeywell Modureg
modulating regulator.
See Page 22, Figure 13.
The Modureg device provides the adjustments for
maximum and minimum firing and is set using the
two adjustments.
See Page 22, Figure 13.
The external control will operate the burner between
these two limits depending on heat demand.
The minimum set point must not be set lower
than the minimum burner pressure stated
on
Page 6, Section 4.2.
11.4.3 Commissioning the Gas Valve
There are two stages to commissioning the
modulation equipment.
The minimum pressure setting must be adjusted
first, any adjustment of the minimum pressure
setting will affect the maximum pressure setting.
For ON/OFF non-modulating operation set the
minimum firing rate to be the maximum burner
pressure as
on Page 6, Section 4.2
11.4.3.1 Set Minimum Pressure
1. Disconnect the leads from the coil of the
Modureg regulator.
2. Connect a suitable manometer to the burner
pressure test point of the main gas valve.
3. Turn on any external controls and allow the
burner to fire for at least five minutes.
4. Remove cap and using a suitable 9mm span-
ner adjust the burner minimum set pressure to
the value shown
on Page 6, Section 4.2.
11.4.3.2 Set Maximum Pressure
(Not Required for ON/OFF burners)
1. Press in the moving shaft of the Modureg valve
and hold in this position while adjusting the
burner maximum pressure to the value shown
on Page 6, Section 4.2.
For adjustments
See Page 22, Figure 13.
NOTE: If the correct burner pressure cannot be
reached, then check the inlet pressure to the
valve, with the burner firing.
See Page 6, Sec-
tion 4.2 for inlet pressure requirements.
Do not continue to adjust the regulator if the
pressure is not changing.
If the inlet pressure is too low to allow a correct
burner pressure setting, then the gas inlet pres-
sure must be corrected before completing the
commission.
2. Release the moving shaft and observe that the
burner pressure returns to the minimum setting.
3. Turn off the external controls and reconnect the
electrical leads to the Modureg regulator.
4. Turn on the external controls and allow the
burner to fire once again observing the burner
pressure.
5. Using the temperature set point device of the
installed control system, set for maximum
burner firing and observe that the burner pres-
sure slowly rises to the maximum as set.
6. Reset the temperature set point by small steps
until the burner pressure slowly drops to the
minimum pressure set. Repeat Step 5 and
observe that the maximum set point is again
achieved.
Check Gas Rate
1. After burner pressure adjustment, allow the
heater to operate for at least 15 minutes and
then re-check settings.
2. Remove the manometer and refit all covers to
the valve and tighten the screw of the outlet
pressure tap.
3. Check gas flow rate at gas meter.
11.5 Combustion Testing (all models)
The only adjustment to alter combustion
performance is burner pressure. Combustion quality
must be tested to prove correct heater operation.
Incorrect results will indicate faults with the
installation or appliance.
Combustion testing must be carried out at full fire
with all covers in place. The flue gas is sampled in
the flue, within 1 meter of the heater. The values of
CO
2 should be between 6.5% to 8.0% for natural
gas and 7.0% to 9.1% for LPG dependant upon
model.
The CO will be up to 80 ppm (0.008%) dry, air free
dependant upon model. Temperature rise of the flue
gases above ambient should be approximately 160°
C to 180° C. Seal test hole in flue after testing.
Following the above operate the heater for 30
minutes at the minimum firing rate. Following this
time the temperature of the products of combustion
in the flue should be measured. If the flue products
temperature is below 80° C then the minimum firing
rate should be increased. Continuous operation of
the burner with flue gas temperature of below 80° C
will cause condensation to form in the heat
exchanger and flue system. This will cause nuisance
water collection and a shortened heat exchanger
life.