Plumbing & Heating FAQ — London

What areas of London does RARE Plumbing cover?

RARE covers prime Central London neighbourhoods including Mayfair, Knightsbridge, Belgravia, Marylebone, Hampstead, St John's Wood and Notting Hill.

Do you offer emergency plumbing and heating callouts?

Yes — RARE offers same-day emergency response for boiler breakdowns, leaks and heating failures across our London service area.

Are RARE engineers vetted, insured and Gas Safe registered?

All RARE engineers are Gas Safe registered, fully insured, DBS-checked and trained to work discreetly in premium London homes.

Do you offer fixed-price quotes before work begins?

Yes — for planned work like boiler installations and underfloor heating, RARE provides a fixed, transparent quote before any work starts.

Does RARE guarantee its plumbing and heating work?

All RARE installations and repairs are covered by our workmanship guarantee, alongside manufacturer warranties on parts and appliances.

How do I book an appointment with RARE Plumbing?

Book online via our booking form, call 020 7458 4949, or get a fixed boiler quote in 3 steps — RARE responds same-day for urgent issues.

How long does a boiler last in London?

A well-maintained boiler in a London home typically lasts 10–15 years. Premium brands like Vaillant and Viessmann can reach 20+ years with annual servicing.

Why does my boiler keep losing pressure?

The most common causes are a water leak somewhere in the system, a faulty pressure relief valve, or bleeding radiators that wasn't re-pressurised afterwards.

Why is my boiler making banging noises?

Boiler banging (kettling) is almost always caused by limescale or sludge on the heat exchanger. London's hard water makes this a very common issue.

What is a combi boiler and how does it work?

A combi boiler combines central heating and instant hot water in one unit — no separate cylinder needed. It's the most popular boiler type in London flats and smaller homes.

Why do London plumbers recommend Vaillant boilers?

Vaillant boilers offer exceptional reliability, excellent parts availability across London, and a strong warranty programme — making them the most-specified premium boiler in the UK.

What do Vaillant boiler error codes mean?

Vaillant boilers display fault codes starting with F (fault) or S (status). The most common are F22 (low pressure), F28 (ignition failure) and F75 (pressure sensor fault).

Should I repair or replace my boiler?

The repair-or-replace decision depends on boiler age, repair cost vs boiler value, and efficiency. Our rule: if repair costs exceed 50% of a new boiler, replace.

How does underfloor heating work?

Underfloor heating (UFH) works by circulating warm water through pipes embedded in the floor, radiating gentle heat upward — more efficient and comfortable than radiators.

What temperature should underfloor heating be set to?

Floor surface temperature should be 25–29°C for comfort. Flow temperature from the boiler is typically 35–55°C — much lower than radiators, maximising efficiency.

Does underfloor heating work with all floor types?

Yes, but performance varies. Stone and tile are most efficient. Engineered wood works well. Thick carpet significantly reduces heat output. Solid wood needs careful specification.

How long does it take to install underfloor heating?

A single-room retrofit typically takes 2-4 days, while whole-house wet UFH installations in a renovation can take 1-3 weeks depending on scope.

Can underfloor heating be retrofitted into an existing London home?

Yes — low-profile retrofit UFH systems can be installed into existing floors without major excavation, ideal for period London properties.

Is underfloor heating more expensive to run than radiators?

No — wet underfloor heating typically runs more efficiently than radiators because it operates at lower flow temperatures, often reducing energy costs.

Can I add an extra bathroom to my London home?

Yes — RARE designs and installs new bathroom plumbing in London properties regularly, including loft conversions, basement extensions and reconfigured floor plans.

What causes low water pressure in London homes?

Low water pressure is usually caused by mains supply issues, scale build-up in old pipework, a faulty pressure reducing valve, or an undersized cylinder.

Why do my pipes make a banging noise (water hammer)?

Banging pipes, known as water hammer, is usually caused by a sudden stop in water flow creating a pressure shockwave — often fixed with an air-filled arrestor.

What is a stopcock and why should I know where mine is?

A stopcock shuts off your home's entire water supply — knowing its location and testing it annually can prevent major flood damage during a burst pipe.

Do I need a water softener for hard water in London?

London sits in a hard water area, so limescale build-up in boilers, cylinders and appliances is common — a water softener significantly reduces damage and extends appliance life.

What's the difference between a plumber and a heating engineer?

Plumbers handle water systems, pipework and fixtures, while heating engineers specialise in boilers, central heating and gas appliances — RARE engineers are qualified in both.

What is power flushing and when do I need it?

Power flushing is a high-velocity water treatment that removes sludge, rust and debris from your central heating system — restoring heat output and efficiency.

How do I balance my radiators for even heating?

Balancing radiators adjusts the flow to each one so heat distributes evenly throughout your home. It involves setting lockshield valves based on temperature measurements.

How long does a power flush take?

A power flush typically takes 6–10 hours for an average London home with 10 radiators. Larger properties or heavily silted systems can take a full day.

Why is my radiator cold at the bottom but hot at the top?

A radiator cold at the bottom is almost always caused by sludge and magnetite buildup settling at the base. A power flush or chemical cleanse will fix it.

Why is my central heating not working?

Central heating failures are commonly caused by low boiler pressure, a faulty thermostat, trapped air in radiators, or a broken pump or valve.

What is the ideal boiler flow temperature for efficiency?

Setting a combi boiler's flow temperature to around 55-60°C (for heating) significantly improves condensing efficiency and can lower gas bills.

How do I bleed a radiator?

Bleeding a radiator releases trapped air using a radiator key on the bleed valve — turn off the heating first and have a cloth ready to catch water.

What is an unvented cylinder and how does it differ from a Megaflo?

An unvented cylinder stores hot water at mains pressure without a header tank. Megaflo is simply the best-known unvented cylinder brand — others include OSO, Telford and Gledhill.

Vented vs unvented cylinders — which is better for a London home?

Unvented cylinders give mains-pressure hot water at every outlet with no loft tank required — the preferred choice for most prime London properties.

How long does an unvented (Megaflo-style) cylinder last?

A well-maintained unvented cylinder typically lasts 10-15 years, or longer with annual G3 servicing and good water quality.

Do unvented cylinders need annual servicing?

Yes — unvented cylinders must be serviced annually by a G3-qualified engineer to remain safe, insured and compliant with building regulations.

Why is my Megaflo cylinder making noise or losing hot water pressure?

Common causes include a waterlogged expansion vessel, scale build-up from hard water, or a faulty pressure relief valve — all fixable by a G3 engineer.

What is a smart thermostat and is it worth it?

A smart thermostat lets you control heating remotely via an app, with features like scheduling, geofencing and learning. Studies show average savings of 10–30% on heating bills.

What's the difference between Heatmiser and Nest thermostats?

Heatmiser offers superior multi-zone control for underfloor heating and larger homes, while Nest suits simpler single-zone properties with strong app design.

Can I control my heating remotely with a smart thermostat?

Yes — smart thermostats like Heatmiser and Nest let you control heating from a smartphone app anywhere with an internet connection.

Why has my Heatmiser neoHub stopped connecting to the app?

neoHub connectivity issues are usually caused by router changes, Wi-Fi dropouts, or a hub firmware update — most are fixed with a hub reboot or router reconnection.

What does a commercial boiler service involve?

A commercial boiler service covers combustion analysis, heat exchanger inspection, safety device testing and flue gas checks — legally required for all commercial properties.

What's the difference between commercial and domestic boiler servicing?

Commercial boiler servicing covers larger, more complex systems with stricter compliance and record-keeping requirements than domestic servicing.

Do commercial buildings need a Legionella risk assessment?

Yes — under ACoP L8, commercial property owners and landlords have a legal duty to assess and manage Legionella risk in water systems.

How often should commercial heating systems be serviced?

Commercial heating systems should be serviced at least annually, with larger or critical systems often benefiting from bi-annual checks and a PPM contract.

Do plumbers need to be Gas Safe registered in London?

Yes — it's a legal requirement. Only Gas Safe registered engineers can legally work on gas appliances in the UK. Always check the register before allowing any gas work.

What is a Legionella risk assessment and who needs one?

A Legionella risk assessment identifies risks of Legionella bacteria growth in water systems. Legally required for all commercial properties and HMOs in London.

How often should I check my carbon monoxide detector?

Test carbon monoxide detectors monthly and replace batteries or the unit as recommended by the manufacturer — usually every 5-10 years.

What should I do if I smell gas in my home?

If you smell gas, turn off appliances, open windows, avoid naked flames or switches, leave the property and call the National Gas Emergency line on 0800 111 999.

How much does a boiler replacement cost in London?

A boiler replacement in London typically costs £2,000–£5,500 including installation, depending on boiler type, brand and property complexity.

How much does underfloor heating cost to install in London?

RARE provides a fixed price for underfloor heating after a free site survey — diagnostic and repair work is charged at our standard hourly rate of £150/hr + VAT.

How much does a plumber cost per hour in London?

RARE charges £150/hr + VAT for standard hours, £195/hr out-of-hours and £275/hr on bank holidays — with no separate call-out fee and members saving 10%.

How much does a new central heating system cost in London?

RARE provides a fixed-price quote for every central heating installation after a free survey — pricing reflects the property size, radiator count and system specification.

How much does an emergency plumbing call-out cost in London?

RARE charges no separate call-out fee — just our standard hourly rate of £150/hr + VAT, rising to £195/hr out-of-hours and £275/hr on bank holidays.

How much does a Gas Safety Certificate (CP12) cost in London?

A domestic Gas Safety Certificate (CP12) from RARE is £180 + VAT, with each additional appliance charged at £45 + VAT.

How often should a boiler be serviced in London?

Every 12 months — without exception. Annual boiler servicing keeps your warranty valid, maintains efficiency and is a Gas Safe requirement for rented properties.

What is a PPM maintenance contract for plumbing and heating?

PPM (Planned Preventative Maintenance) is a scheduled service contract covering annual boiler servicing, system checks and priority response — protecting your home year-round.

What's included in an annual boiler service?

An annual boiler service includes a visual inspection, safety checks, flue gas analysis, component cleaning and a Gas Safety Certificate on completion.

How often should cold water storage tanks be cleaned?

Cold water storage tanks should be inspected annually and cleaned/disinfected as needed to control Legionella risk, per HSE ACoP L8 guidance.

What maintenance does a heating system need going into winter?

Before winter, have your boiler serviced, bleed radiators, check system pressure, and top up inhibitor to avoid mid-winter breakdowns.