35. During the sequence of a combi operation, after the air pressure switch moves to the normally open position, the:
High-fire solenoid closes
Spark starts *******cheers chilli985
Pump overrun operates
Fan speed changes low to high
37. The maximum distance between open vent and cold feed is:

150 mm?
500 mm ?
300 mm ?
1m ?
39. During the summer months, the customer reports that the upstairs radiators are heating up when hot water only is switched on: This problem could be cured by:
Fitting a variable speed pump
Fitting an anti-gravity valve on the central heating flow ***
(to stop heat rising through the flow)
Fitting an automatic air-release on the Primary flow
Fitting a non-return valve on the open vent
40. The customer complains of no hot water. This problem could be cured by
Fitting a variable speed pump
Fitting an anti-gravity valve on the central heating flow
Fitting an automatic air-release on the Primary flow ***
(to get rid of trapped air which would stop the
cyelender heating up)
Fitting a non-return valve on the open vent
32. Water discharging from a pressure relief valve during heat-up of a combination boiler, may indicate that the:
Thermostat is set too high
Pressure vessel is de-pressurised or too small
(no space to expanded) *****cheers kevplumb
The heat exchanger is partially blocked
System by-pass is incorrectly set
33. The most likely cause of the domestic water being too hot from a combination boiler could be:
Thermostat is set too low
Airflow switch is defective
Blocked or scaled heat exchanger **
(the heat exchanger is now smaller now less water will pass
so there for increase in water temp)
Pump speed is too high
34. By incorporating a dual element heat exchanger into the design of a combination boiler, the components made redundant are the:
Diverter valve and calorifier *
(you have converted the syestem to a combi has them builtin?)
Secondary thermostat and bypass
2 port diverter valve and secondary thermostat
Twin pass heat exchanger
High-fire solenoid closes
Spark starts *******cheers chilli985
Pump overrun operates
Fan speed changes low to high
37. The maximum distance between open vent and cold feed is:

150 mm?
500 mm ?
300 mm ?
1m ?
39. During the summer months, the customer reports that the upstairs radiators are heating up when hot water only is switched on: This problem could be cured by:
Fitting a variable speed pump
Fitting an anti-gravity valve on the central heating flow ***
(to stop heat rising through the flow)
Fitting an automatic air-release on the Primary flow
Fitting a non-return valve on the open vent
40. The customer complains of no hot water. This problem could be cured by
Fitting a variable speed pump
Fitting an anti-gravity valve on the central heating flow
Fitting an automatic air-release on the Primary flow ***
(to get rid of trapped air which would stop the
cyelender heating up)
Fitting a non-return valve on the open vent
32. Water discharging from a pressure relief valve during heat-up of a combination boiler, may indicate that the:
Thermostat is set too high
Pressure vessel is de-pressurised or too small
(no space to expanded) *****cheers kevplumb
The heat exchanger is partially blocked
System by-pass is incorrectly set
33. The most likely cause of the domestic water being too hot from a combination boiler could be:
Thermostat is set too low
Airflow switch is defective
Blocked or scaled heat exchanger **
(the heat exchanger is now smaller now less water will pass
so there for increase in water temp)
Pump speed is too high
34. By incorporating a dual element heat exchanger into the design of a combination boiler, the components made redundant are the:
Diverter valve and calorifier *
(you have converted the syestem to a combi has them builtin?)
Secondary thermostat and bypass
2 port diverter valve and secondary thermostat
Twin pass heat exchanger
