Plumbing and Heating Terms Explained: A Homeowner’s Guide

Plumbing and Heating Terms Explained

Understanding your home’s plumbing and heating system can be confusing if you’re not familiar with the terminology. To make things easier, we’ve broken down some of the most common terms you might hear from your plumber or heating engineer, along with what they actually mean for your home.

Flow Rate

The flow rate measures how much water passes through your system in a set amount of time, usually litres per minute (L/min). A higher flow rate means faster water delivery from your taps and showers. If your flow rate is low, you may notice weak water pressure.

• Low flow rate causes: narrow pipes, long pipe runs, or blockages in valves and fittings.
• How to improve it: check for scale buildup, leaks, or upgrade to a mains booster pump.
• Tip: measure your flow rate by timing how long it takes to fill a 1-litre jug from a fully opened tap.

Condensing Boiler

A condensing boiler is designed to recover heat from exhaust gases that older boilers would simply waste through the flue. By reusing that heat, condensing boilers are far more efficient and produce fewer emissions.

• Typically over 90% efficient compared to older models.
• Lower running costs and smaller carbon footprint.
• Now the standard type of boiler installed in UK homes.

TRVs (Thermostatic Radiator Valves)

TRVs are the small adjustable valves fitted to radiators that let you control the temperature in individual rooms. They sense the air temperature and automatically open or close to maintain comfort levels.

• Turn them down in unused rooms to save energy.
• Do not fit TRVs on radiators in the same room as your main thermostat.
• Modern TRVs can be digital or even smart-controlled via apps.

Combi Boiler

A combination or ‘combi’ boiler provides both heating and hot water directly from one compact unit. It heats water on demand, so there’s no need for separate storage tanks.

Benefits of a combi boiler:

• Instant hot water whenever you need it.
• Space-saving – no hot water cylinder required.
• Ideal for small to medium-sized homes.

System Boiler

System boilers use a separate hot water cylinder but most other parts are built in. They can deliver strong water pressure and are well suited to homes with more than one bathroom.

Regular (Conventional) Boiler

Regular boilers, also known as conventional or heat-only systems, use both a cold water storage tank and a hot water cylinder. They can supply multiple taps at once but require more space.

Power Flushing

Power flushing is a deep clean for your central heating system. It removes sludge, rust, and debris that build up over time inside pipes and radiators.

• Improves radiator heat output.
• Reduces noise from your boiler and system.
• Can extend the lifespan of your heating components.

Pressure Relief Valve

The pressure relief valve (PRV) is a key safety component that stops your boiler or plumbing system from becoming over-pressurised. It automatically opens to release excess water or pressure when needed. Repeated leaks from this valve should always be checked by a professional.

Magnetic Filter

A magnetic filter captures rust and metal debris circulating through your heating water. It helps protect your boiler from internal damage and improves efficiency. These filters should be cleaned or serviced annually.

Stopcock

The stopcock (or stop valve) controls the mains water supply into your property. Knowing where it is located is vital in case of a leak or burst pipe. Turning it clockwise closes off your water supply.

• Usually found under the kitchen sink or near the water meter.
• Test it once or twice a year to ensure it still works freely.
• In emergencies, turn off the stopcock to prevent flooding.

Trap and U-Bend

These are the curved sections of pipework found beneath sinks, baths, and showers. They hold a small amount of water that acts as a seal to stop unpleasant smells and gases coming back up from the drains.

• If a trap dries out, you may notice bad odours – simply run some water to refill it.
• Modern traps are designed for easy cleaning and access to remove blockages.

Cistern

The cistern is the tank on your toilet that stores water ready for flushing. It fills automatically after each flush using a float valve. If your toilet runs continuously, the cistern mechanism may need adjustment or replacement to prevent water waste.

Waste Pipe

Waste pipes carry used water from sinks, baths, and appliances to the main drain. They should be correctly angled to allow water to flow freely and prevent blockages. Over time, grease, soap, and hair can build up and slow drainage.

Need Expert Help?

Plumbing and heating terms help you understand your home heating and plumbing systems better and if you’re unsure what type of boiler or plumbing system you have, or you’d like professional advice on improving performance and efficiency, our qualified engineers at Hynes Plumbing & Heating are here to help. We provide reliable plumbing and heating services across Northern Ireland – from full installations to emergency repairs.

Contact us today to book a service or speak to a member of our team.