Roberts Gorden MGB Series Manual de Serviço descarregar pdf (Página 49)

SECTION 10: COMMISSIONING

43 of 85

Figure 18: Gas-Fired Heater Control Box Sequence

10.3 Commissioning the Two-Stage (High/Low)

Burner (gas heaters)

High/Low burners have additional specific

requirements. Follow the bu rner manufacturer's

instructions and the data provided on Page 11,

Section 4.4 through Page 14, Section 4.8.

10.3.1 Set Gas Rate

1. S witch off and refit the main gas valve plug

(removed earlier to allow the main gas valve to

operate).

2. Switch on again and allow the burner to fire and

to settle for a few minutes.

3. Adjust the main gas burner pressure to the

value given in the relevant Data Table for the

model concerned using the Main Gas Regula-

tor (accessed under the s

wivel cover).

The results of setting the gas flow rate by using

burner pressure only can lead to quite wide

variations in heat input due to the nature of the

burners used.

NOTE: If the correct burner pressure cannot be

reached, then check the inlet pressure to the valve,

with the burner firing. See Technical Data Tables on

Page 11, Section 4.5 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 the correct

burner pressure setting, then the gas inlet pressure

must be corrected before completing the

commissioning.

10.3.2 Check Gas Rate

It is important to check that the gas rate set during

the commissioning is within ± 5% of the required

flow rate.

This may be achieved by checking the gas flow to

the heater

wherever possible by using the gas meter

and timing the flow through the meter. The results

should be compared with the required flow rate for

the model given in the Data Tables, adjusting the

burner pressure to correct for any error. Checking

the gas rate must be carried out with all other

appliances including any pilots, turned off.

1. A ft e r b urner 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.

10.3.3 Control - Gas-Fired Heaters

For High/Low, follow the general sequence as

described below and also have extra functional

stages related to air damper positions. Refer to the

burner manufacturers instru

ctions for further detail.

Gas burners have two pressure switches; One is

configured to cover combustion air and reaction to

increases in combustion chamber pressure. The

second pressure switch is used for monitoring

incoming gas supply pressure.

10.3.4 Description of Gas-Fired Heater Control

The gas-fired burner fitted to all cabinet heaters is

controlled by a full sequence plug-in control. This

Always disconnect the power supply before installing or removing the control unit. Do not

attempt to open or carry out repairs on the control unit.

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Roberts Gorden MGB Series Manual de Serviço Página 49

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