phase 1 hot water

State the minimum size of open vent pipe which terminates over a cold water storage cistern that is allowed under the Water Regulations for a secondary domestic hot water system.

• 15mm

• 22mm

• 28mm

• 32mm

Answer explanation

The minimum size of an open vent pipe terminating over a cold water storage cistern for a secondary domestic hot water system is 22mm, as specified in the Water Regulations, ensuring proper venting and system efficiency.

What is the recommended temperature setting for the thermostat to an immersion heater in a hot water storage cylinder?

• 90°C

• 70°C

• 60°C

• 50°C

Answer explanation

Hot water storage should be @ 60 degrees to prevent limescale build up while minimizing the risk of scalding and energy waste.

Which type of hot water storage cylinder is shown in this diagram?

• Direct cylinder

• Combination unit

• Double feed indirect cylinder

• Single feed indirect cylinder

Answer explanation

The diagram depicts a double feed indirect cylinder, which has two feeds for hot water supply. 1 is the CWSC feeding the hot water storage tank and the other is the F&E tank filling the heating system side giving the total of 2 feeds.

A hot water storage cylinder heated by an immersion heater only is considered to be what type of hot water storage system?

• Direct

• Indirect

• Electrolytic

• Instantaneous

Answer explanation

A hot water storage cylinder heated by an immersion heater is classified as a direct hot water storage system because the heater directly heats the water without any intermediary fluid.

When water is heated in a hot water storage cylinder, stratification will occur. Which of the following best describes stratification?

• The hottest water is in the middle of the cylinder; the coldest water is at the top and bottom of the cylinder

• The coldest water is at the top of the cylinder and the hottest water is at the bottom of the cylinder

• The coldest water is in the middle of the cylinder; the hottest water is at the top and bottom of the cylinder

• The hottest water is at the top of the cylinder and the coldest water is at the bottom of the cylinder

Answer explanation

Stratification occurs when heated water rises, causing the hottest water to be at the top of the cylinder and the coldest water to settle at the bottom. Thus, the correct description is that the hottest water is at the top and the coldest at the bottom.

The recommended minimum size of primary circulation pipework between a small (under 35kW) solid fuel boiler serving a direct hot water cylinder only is:

• 15mm

• 22mm

• 28mm

• 35mm

Answer explanation

The recommended minimum size for primary circulation pipework for a small solid fuel boiler is 28mm. This size ensures adequate flow and efficiency for heating a direct hot water cylinder.

What is the electrical power rating of a typical domestic immersion heater?

• 3kW

• 3.7kW

• 4kW

• 10kW

Answer explanation

A typical domestic immersion heater has an electrical power rating of 3kW. This rating is common for household use, providing efficient heating without excessive energy consumption.

The difference between a single feed and a double feed indirect cylinder is:

• the single feed cylinder requires a booster pump

• the single feed cylinder does not need a separate feed and expansion cistern

• the single feed cylinder requires a twin port motorised valve arrangement

• the single feed cylinder does not require an open vent pipe to the secondary storage cistern

Answer explanation

The correct choice is that the single feed cylinder does not need a separate feed and expansion cistern, which simplifies the system compared to a double feed indirect cylinder that requires both.

An unvented cylinder has a range of safety controls to prevent hot water reaching which temperature?

• 85°C

• 90°C

• 95°C

• 100°C

Answer explanation

An unvented cylinder is designed to prevent water from reaching 100°C to ensure safety and avoid the risk of boiling and pressure build-up. Therefore, the correct answer is 100°C.

Which system works in a similar way to an indirect cylinder, except in reverse?

• Unvented cylinder

• Thermal store unit

• Direct cylinder

• Combination unit

Answer explanation

A thermal store unit operates similarly to an indirect cylinder but in reverse, as it stores heat for later use rather than heating water directly, making it the correct choice.