page no. 23 of 36
OUH Range Users, Installation & Servicing Instructions Doc Ref M105 issue 5.8 Apr 2020.
Typical Figures:
Model
20
30
45
60
High Fire CO2
%
12.5
12.5
12.5
12.75
FGT (nominal)
°C
195
175
250
300
Low Fire CO2
%
12.5
12.5
12.5
12.0
FGT (nominal)
°C
135
150
200
235
The running current of the centrifugal fan must be
checked once the heater is running and compared with
the following table.
WARNING: Exceeding the MAX running
current will cause the fan’s thermal overload
to trip!
Using a clamp meter around the fan power cable and with
all side panels closed, check the running current of the
centrifugal fan once the heater is running and compared
with the following table.
Adjust the balancing dampers within the airflow ductwork
system to achieve a current suitable for the model in
question.
Model
Motor
kW
Typical
Running
Current
Max
Running
Current
OUH20 C
0.55
4.3A
4.3A
OUH30 C
0.55
4.33A
4.3A
OUH45 C
1.1
5.54A
8.0A
OUH60 C (35s)
1.1
8.0A
8.0A
OUH60 C (35s)
1.5
9.7A
10.0A
Ensure that the fan and limit settings are as follows:-
Thermostat settings:-
Fan Off: 86°F/30°C Fan On: 122°F/50°C
Limit:
OUH20
239°F/115°C
OUH30-60
194°F/90°C
On ducted units ensure that the main air fan comes on no
later than 150 to 180 seconds after the main burners light
1. Ensure the oil gauge is connected. Remove the sample
point cover plug from the outlet flue length and insert a
CO2 measuring instrument.
2. Turn ON the main electricity supply and check that the
following sequence of events occur. i) Burner fan runs. ii)
Ignition spark is heard. iii) Main flame is established.
Low Fire
Pressure
Adjustment
High Fire
Pressure
Adjustment
Gauge
Connection
Check that the High Fire burner pump pressure agrees
with that stated on the heater data plate and in section
1.2. If necessary adjust the pump pressure by rotating
the high fire adjustment screw clockwise (+ positive),
anticlockwise (- negative)
Check that the Low Fire pump pressure agrees with that
stated on the heater data plate and in section 1.2. If
necessary adjust the pump pressure by rotating the low
fire adjustment screw clockwise (+ positive), anticlockwise
(- negative)
If any adjustments have been made, re-check both high
and low fire once more.
3. Measure the CO2 content of the flue gases. If
necessary adjust the combustion air damper of the burner
(Refer to the Burner Instructions) to obtain a CO2 reading
as indicated in section 1.2 (±0.5)
4. Turn OFF the burner. Remove oil gauge and refit gauge
connection plug, refit flue sample point cover plug.
