CENWAT Pipework Sizing and Installation

Question 1

What is the standard method for calculating the flow rate used for sizing domestic central heating pipework in the UK?

Accepted Answer

Calculate from the heat load using the formula: flow rate equals heat load divided by specific heat capacity multiplied by temperature difference

Answer

Use the boiler manufacturer maximum flow rate only

Answer

Use a fixed rate of 10 litres per minute for all systems

Answer

Base it on the number of radiators only

Question 2

What is the recommended design flow and return temperature difference (DeltaT) for a condensing boiler system to maximise efficiency?

Accepted Answer

20 degrees C

Answer

5 degrees C

Answer

11 degrees C

Answer

30 degrees C

Question 3

When installing copper pipework for central heating, what is the minimum clip spacing for horizontal 15mm copper pipe?

Accepted Answer

1.2 metres

Answer

0.6 metres

Answer

1.8 metres

Answer

2.4 metres

Question 4

What is the purpose of inhibitor in a central heating system, as recommended by BS 7593?

Accepted Answer

To prevent internal corrosion and limescale formation

Answer

To increase the water temperature

Answer

To reduce the water pressure

Answer

To improve boiler combustion

Question 5

What is the maximum velocity of water recommended in domestic central heating pipework to avoid noise?

Accepted Answer

1.5 m/s

Answer

0.5 m/s

Answer

1.0 m/s

Answer

3.0 m/s

Question 6

When installing a new central heating system, what cleaning procedure does BS 7593 require before adding inhibitor?

Accepted Answer

A pre-commission clean using an appropriate cleaning agent, followed by thorough flushing

Answer

No cleaning is required for new systems

Answer

A hot flush with clean water only

Answer

Simply adding inhibitor to the system water