Boiler Servicing. Boiler Repair. Boiler Installation

A combination, or combi boiler, is a single unit that provides all the heating and hot water requirements for the home. Combination boilers connect directly to the mains cold water supply, providing hot water on demand. As they do not have a hot water tank they are a great choice for many smaller homes, especially houses and flats that only have one bathroom, as they have a lower hot water and heating demand than larger properties. This is fine so long as you have good water pressure and don’t require large volumes of water all at once, as this will impact the flow rate. The central heating gets controlled for both time and temperature most commonly with a programmable thermostat for ease of installation.
 

Combi boiler benefits

• Take up less space - a combi boiler doesn't need a water tank, so you'll have more space.

• Aesthetics - all components are within the boiler casing, making it more compact and neater to look at.

• Easier to service - due to their popularity, most engineers are trained to work on combi boilers, making it easier to find a qualified one in your local area.

• Instant heated water - you don't have to wait for a water tank to heat up; a combi boiler will immediately supply unlimited hot water.

Cons of combi boilers

• Only one shower at a time - the rate at which water is supplied reduces when the boiler is trying to provide hot water to two or more places at the same time. This typically means it isn't possible to run more than one bath or shower at a time, or a shower while someone else does the washing up using hot running water.

• Limited by mains pressure - they don't work as well in homes with poor water pressure.

• Moving parts - the boiler unit contains moving parts, so there is more potential for things to go wrong than with a conventional boiler.

Conventional boilers, also referred to as 'heat only' boilers or regular boilers are the older method, but the most common type used for heating homes. Unlike a combi boiler, a conventional system requires a cylinder to store hot water and provides heat directly to your radiators. This requires more space and typically properties with this type of system will have an airing cupboard to house the cylinder and associated controls.

The controls for these systems tend to be a bit more complex as time and temperature has to be set for both heating and hot water. Conventional systems are usually vented, or 'open vented', so require extra space in the loft for header tanks needed to provide system pressure.

Conventional heat-only boiler benefits

• Good for larger households - if you have multiple bathrooms with people frequently needing to use hot water at the same time, a heat-only boiler will meet this demand.

Cons of conventional heat-only boilers

• Doesn't give hot water on demand - you have to wait for the water in the cylinder to heat up.

• Temporarily run out of hot water - if lots of people are using the hot water, it's possible to run out and you'll have to wait for the hot water tank to refill.

• Takes up space - you'll need room for cold water feed and expansion tanks to be installed.

• Less efficient than combi boilers - as you will lose heat from the stored hot water in the hot water cylinder.

• Installation costs - can be more expensive to install than a combi boiler if you don't already have the cold water feed and expansion tanks.

This is the more contemporary method for heating larger properties using stored hot water. Like a conventional boiler system, the domestic hot water is supplied to the taps from a cylinder that is time and temperature controlled. These systems are sometimes known as 'closed vent' or sealed system boilers as they are unvented meaning that they are pressurised from the water mains, so header tanks in the loft are not required, freeing up space.

A system boiler is the perfect choice if you think you'll need a heat-only boiler but don't want lots of external components.

System boiler benefits

• Good for larger homes - if you have multiple bathrooms with people frequently needing to use hot water at the same time, a system boiler will meet this demand.

• Takes up less space than a regular boiler - you don't need the space for a large cold water tank in the loft.

Cons of system boilers

• Takes up more space than a combi boiler - you still need space for a hot water cylinder.

• Doesnt provide heated water on demand - you have to wait for the water in the cylinder to heat up.

• Temporarily run out of hot water - if lots of people are using the hot water, it's possible to run out and you'll have to wait for the hot water tank to refill.

• Less efficient than a combi boiler - as you will lose heat from the stored hot water in the hot water cylinder.

This is a less common system, storage combi boilers work like a combination boiler, but have an internal hot water cylinder built into the boiler.

They are a good solution if you have a higher hot water demand but don't have the space for the separate hot water cylinder that a system or heat-only boiler requires.

Storage combi boiler benefits

• Benefits of a combi and system boiler in one - hot water on-demand, but the hot water cylinder means hot water can go to several outlets at the same time without the pressure dropping (like it would with a regular combi boiler).
• Takes up less space than a system boiler - the hot water cylinder is built into the boiler body, rather than being separate like a system boiler.
• Cheaper to install than a system or heat-only boiler - as everything is built in, the unit is typically cheaper and is less expensive to install.
• Solar thermal panel compatible - as it stores hot water, you can keep that water warm with solar thermal, which isn't possible with just a typical combi boiler.

Cons of storage combi boilers

• Take up more space than a combi boiler - due to the hot water cylinder built into the boiler's body.
• System boilers can meet larger hot water demands - storage combi hot water tanks are typically sized between 40 and 200 litres, but some hot water tanks for system boilers can be 500 litres or more.
• Less choice - being a less common type of boiler, there are fewer storage combi systems to choose from.