An airing cupboard is a cupboard, usually upstairs, built around your home’s hot water cylinder, and its gentle warmth has traditionally been used to air and dry towels, bedding and clothes. Inside you will usually find the cylinder and its immersion heater, plus the valves, thermostat and pipework that control your heating and hot water, and on a mains pressure (unvented) system, a set of safety devices that should only be touched by a qualified engineer.

Why homes have an airing cupboard

Most British homes built before combi boilers became common were fitted with a hot water cylinder. Hot water in a tank loses a little heat all the time, even when insulated, so builders put the cylinder in a slatted cupboard where that heat would be useful for airing linen. The name stuck, and in Ireland the same space is often called the hot press.

Today, the airing cupboard is really the control room for your hot water and, in many homes, your heating as well. Knowing what is in there helps you spot a problem early, explain it clearly to a plumber, and know when a mains pressure cylinder needs a qualified unvented cylinder engineer.

What is inside an airing cupboard

Part	What it does	What to look out for
Hot water cylinder	Stores water heated by the boiler or an immersion heater	Damp patches, corrosion, or water around the base
Insulation	A jacket on older copper cylinders, or factory foam on newer ones	Old cylinders with thin or missing jackets waste heat
Immersion heater	An electric element that heats the water as a backup or main source	A switch left on all the time can run up your electricity bill
Cylinder thermostat	A dial strapped to the cylinder that tells the boiler when the water is hot enough	If set too low, water may not reach a safe storage temperature
Motorised valve	Sends hot water from the boiler to the heating, the cylinder, or both	A sticking valve can cause no heating or no hot water
Pump	Circulates water from a system or regular boiler, if it is not inside the boiler	Humming, noise or no circulation
Wiring centre	Connects the programmer, thermostats, valves and boiler	Mains voltage. Leave it to an engineer
Vent and cold feed pipes (vented only)	Link the cylinder to the cold water tank in the loft	Leaks, or the tank overflowing
Safety devices (unvented only)	Expansion vessel, pressure reducing valve, relief valves, tundish and discharge pipe	Water running through the tundish

Vented or unvented: how to tell which cylinder you have

There are two main kinds of cylinder, and they behave very differently.

A vented cylinder is fed by a cold water storage tank in the loft. Gravity supplies the pressure, so hot water pressure depends on how high the tank is. You will see a vent pipe rising from the top of the cylinder and a cold feed pipe coming down from the loft. Showers upstairs are often weak unless there is a pump.

An unvented cylinder is fed straight from the mains, so hot water comes out at mains pressure. There is no loft tank. You will see an expansion vessel (often a round red or white tank on the wall nearby, though some cylinders have an internal air bubble instead), a pressure reducing valve on the incoming mains, relief valves on the cylinder, and a tundish, a small open funnel in the discharge pipe. The cylinder usually carries a label about its installation and safety devices.

	Vented cylinder	Unvented cylinder
Water supply	Cold water tank in the loft	Direct from the mains
Hot water pressure	Low to medium, depends on tank height	Mains pressure, strong showers
Loft tank needed	Yes	No
Safety devices	Open vent pipe	Expansion vessel, relief valves, tundish, energy cut-out
Who can install it	A competent plumber	A qualified unvented installer, under building regulations
Servicing	Occasional checks	Manufacturers recommend an annual service

Unvented cylinders store hot water under pressure, so building regulations require them to be installed by a competent person and fitted with safety devices that stop the water overheating and carry any discharge away safely. Our unvented cylinders service covers installation, annual servicing and repairs.

Common airing cupboard problems

No hot water, but the heating works

This usually points to the motorised valve, the cylinder thermostat or the programmer, or on an electric-only system, the immersion heater. Our guide to no hot water but the heating works walks through the checks you can safely do.

Water dripping from the tundish

On an unvented cylinder, water running or dripping through the tundish means a safety valve is releasing. The cause is often a failed expansion vessel, a faulty pressure reducing valve or a relief valve that is not reseating. It is not something to ignore, and the fix needs a qualified engineer.

Leaks and damp

A wet floor or damp shelf in the airing cupboard can come from a pipe joint, a valve, the immersion heater boss or the cylinder itself. Old copper cylinders can eventually corrode through. Put a tray under a slow drip, keep the electrics dry, and get it looked at before it damages the ceiling below.

Weak hot water pressure

On a vented system, weak hot water is often down to the height of the loft tank. If both hot and cold are weak throughout the house, read our guide to low water pressure in the whole house.

What you can safely check yourself

1. Check the programmer is set to give hot water at the times you expect.
2. Check the cylinder thermostat dial is set sensibly, usually around 60 degrees.
3. See whether the immersion heater switch has been left on or off.
4. On a vented system, look in the loft to check the cold water tank has water in it.
5. On an unvented system, look at the tundish for running water and check the pressure gauge if there is one.
6. Look for drips, damp or corrosion around joints and valves.

Do you still need an airing cupboard?

Not always. When a regular or system boiler is replaced with a combi, the cylinder and loft tanks can be removed, freeing the airing cupboard for storage or a bigger bathroom. That works well in smaller homes with one bathroom. In homes with two or more bathrooms used at once, a cylinder still makes sense, and an unvented cylinder gives mains pressure showers throughout. Heat pumps also need a hot water cylinder, so if you are thinking about one in future, keep the space. Our guide to the best combi boilers explains when a combi suits and when it does not, and our boiler installation team can advise on the right setup for your home.

What it costs with Vantage

In normal working hours there is no call-out fee. After the first hour, time is charged in half-hour steps, and parts are quoted before we fit them. Evening, weekend and overnight visits are charged at the out-of-hours rates. Every rate is published on our prices page, so you know what you will pay before we arrive. If you need a new cylinder, we give you a fixed price before any work starts.

Frequently asked questions

What is the point of an airing cupboard?

It houses the hot water cylinder and the controls for your hot water, and the warmth from the cylinder keeps linen and towels dry and aired. It also keeps the cylinder and its valves together in one place for servicing.

Do homes with a combi boiler have an airing cupboard?

Often they still have the cupboard, but not the cylinder. A combi heats water on demand, so when one is fitted the old cylinder is usually removed and the cupboard is used for storage.

Is it safe to dry clothes in the airing cupboard?

Yes, drying and airing linen is what it was designed for. Keep items off the immersion heater and wiring, leave some space for air to move, and do not pack damp washing in so tightly that moisture builds up.

Why is my airing cupboard so hot?

A cylinder with a thin or missing insulation jacket, an immersion heater left switched on, or a sticking motorised valve can all make the cupboard hotter than usual. Better insulation saves energy and keeps the cupboard at a gentler warmth.

How often should an unvented cylinder be serviced?

Manufacturers recommend an annual service. The engineer checks the expansion vessel charge, the relief valves, the pressure reducing valve and the discharge pipe, which keeps the safety devices working and the warranty valid.

Hot water cylinder help in Hertfordshire, Bedfordshire and Cambridgeshire

If something in your airing cupboard is leaking, dripping through the tundish or not heating, our engineers can find the cause and fix it. See our unvented cylinders page or call 01462 506374, answered 24 hours a day, 7 days a week.