306A Water Heating Systems

Question 1

What is the function of the temperature and pressure (T&P) relief valve on a water heater?

Accepted Answer

To release water if the temperature exceeds 99°C or pressure exceeds 1035 kPa (150 psi), preventing a catastrophic tank failure

Answer

To regulate the water temperature for the user

Answer

To drain sediment from the tank

Answer

To control the gas supply to the burner

Question 2

Where must the discharge pipe from a T&P relief valve terminate?

Accepted Answer

Within 150 mm of the floor or to an approved indirect waste receptor, with an air gap

Answer

Into the sanitary sewer directly

Answer

Back into the cold water supply

Answer

Outside the building through the wall

Question 3

What is the minimum capacity of a residential water heater for a family of four?

Accepted Answer

190 litres (50 gallons)

Answer

100 litres (26 gallons)

Answer

150 litres (40 gallons)

Answer

284 litres (75 gallons)

Question 4

What is the 'recovery rate' of a water heater?

Accepted Answer

The number of litres of water the heater can raise by a set temperature in one hour

Answer

The speed at which the heater drains

Answer

The time it takes for the tank to cool down

Answer

The rate at which the heater fills from the cold supply

Question 5

What is the purpose of an anode rod in a storage-tank water heater?

Accepted Answer

To sacrificially corrode instead of the tank lining, extending the tank's life

Answer

To heat the water electrically

Answer

To filter sediment from the water

Answer

To regulate water pressure inside the tank

Question 6

What minimum clearance is required around a gas-fired water heater for combustion air and servicing?

Accepted Answer

As specified by the manufacturer, typically 150 mm on sides and 300 mm in front

Answer

No clearance is needed

Answer

1 metre on all sides

Answer

Only clearance above the unit is required