Central Heating System Design Flashcards

What is the function of a thermostatic radiator valve (TRV)?

Answer: To regulate the flow of water through the radiator based on room temperature

A TRV senses the air temperature around it and automatically adjusts the flow of hot water through the radiator to maintain the set room temperature.

On which radiator should a TRV NOT normally be fitted in a wet central heating system?

Answer: The radiator in the room where the room thermostat is located

A TRV must not be fitted in the same room as the room thermostat, as both devices would compete for control, potentially causing the boiler to short-cycle or overheat.

What is the purpose of a system filter (magnetic filter) in a central heating system?

Answer: To capture magnetite and debris to protect the boiler heat exchanger

A magnetic system filter captures iron oxide (magnetite) and other debris circulating in the system, preventing damage to the boiler heat exchanger and pump.

What minimum efficiency is required for a new gas boiler installed in England under Building Regulations?

Answer: 92% ErP (energy-related products) rating

Under Building Regulations Part L, new gas boilers must meet a minimum ErP efficiency rating, currently requiring A-rated condensing boilers with around 92% seasonal efficiency.

Which component prevents water from flowing backwards through the heating circuit?

Answer: Non-return valve (check valve)

A non-return valve (check valve) allows water to flow in one direction only, preventing backflow which could cause mixing of circuits or system malfunction.

What does the term 'dead leg' refer to in a hot water system?

Answer: A section of pipework that does not circulate, causing water to cool

A dead leg is a length of pipe where water sits stagnant and cools between draw-offs. Long dead legs waste water and energy and can increase Legionella risk.