Types of boiler & Heating system
COMBINATION OR COMBI’ BOILER
A boiler which produces all your hot water on demand and gives you all the heating required to keep you warm all winter. All the controls and components (excluding the thermostat & programmer) are housed within the boiler. This type of heating system does not require a hot water cylinder or cisterns in the loft, therefore is great for space saving
Ideal for:
Flats, maisonettes and houses of a modest size. There are more powerful combi’s available for bigger houses but these do command a high price
Advantages
- Space Saving- no hot water cylinder, no cisterns in the loft or connecting pipe work
- All taps at mains water pressure
- Fresh mains water to your bathroom, not from a cistern in the loft
- Endless hot water, heated on demand, meaning there’s no hot water cylinder to run out to cold
- You only have to maintain the boiler with no cisterns or pipes in the loft to worry about
- If you’re having a shower and somebody runs a tap in the kitchen your shower will go cold whilst that tap is being run
- Can’t have a power-shower
- A 24Kw boiler with a hot water flow rate of 9 litres/ min will be quite slow to fill a bath, although will be fine for a shower
- No stored hot water
- Gas pipe work must be calculated to the correct size, usually larger than a traditional boiler- thus, you may need a new gas pipe run from the meter to boiler.
- Can be bad in high top-floor flats, with poor water pressure.
TRADITIONAL OPEN VENTED OR HEAT ONLY SYSTEM
Consists of:
- Boiler, floor standing or wall mounted
- Hot Water Cylinder, often in an airing cupboard
- A pump, motorised diverter valve(s) & wiring centre
- 2 x cisterns in the loft. One large the other small
Ideal for:
Houses from 3/ 4 beds & upwards. You may inherit this type of system if you take on an older property.
Advantages
- Supply of hot water always available via cylinder
- Great for homes with low pressure mains water
- Reliable and understood technology
- Hot water can be boosted with a pump, to give a Power-shower
- Lots of hot water with a good flow rate per/ min. Often comes with a back up of an electric immersion heater/ element inserted inside your cylinder.
- Older boilers, for this type of system, often very robust
Disadvantages
- Space Consumed by - a hot water cylinder, 2 x cisterns in the loft & connecting pipe work
- Internal corrosion (rust) to radiators and boiler, caused by air in the system
- Un-insulated pipes in your loft can freeze
- Bathroom cold water is stored in a cistern in the loft giving potential hygiene problems.
- Extreme worst case scenario - Legionnaires’ disease which develops in still water between 20 & 45ºC
UN-VENTED SEALED SYSTEMS
Requires a boiler and an Un-Vented hot water cylinder - which is often referred to as a Megaflo – this is a makers name, like Hoover. Provides all your heating and hot water.
A sealed system of pipe work and components which are pressurised above atmospheric pressure. The system is fed directly from the mains water supply. With a Traditional Open Vented system (see previous entry) there are heating and hot water vent pipes terminating over the loft based cisterns; the unvented system does away with such pipe work and cisterns.
Ideal for:
Brilliant heating and hot water system for homes 2/ 3 beds and upwards.
Advantages
- Gallons of hot water at mains pressure, giving fabulous showers
- Cold water at mains pressure to all taps
- Supply of hot water always available via unvented cylinder
- Has a back-up of an electric immersion heater/ element inserted inside the cylinder - great for topping up your hot water supply when there is a high demand of hot water.
- Space saving in your loft - no cisterns in the loft or inter-connecting pipe work
- Being a sealed system Internal corrosion (rust) to radiators and boiler, caused by air in the system is virtually eliminated
- Risk of contamination from cold water storage eliminated - you have no cistern in the loft
- Unvented cylinders can be located in many places, even the loft
Disadvantages
- To operate successfully the water cylinder needs a good mains water pressure supply
- To achieve a good mains water pressure supply you might need a new dedicated cold water supply pipe from your in-coming water main to the new hot water cylinder
- In addition to the boiler, an unvented cylinder requires an annual service
CENTRAL HEATING VARIATIONS – The Sealed System
Traditional, Open Vented Heat Only Systems with a cylinder in the airing cupboard and cisterns in the loft can be converted to what we call a Sealed System. The main benefit being that a sealed system virtually eliminates internal corrosion (rust) to radiators and boiler, caused by air in the system.
Ideal When: Up-grading a Traditional, Open Vented Heat Only Boiler and installing a new ‘System’ boiler. At a later date your traditional copper hot water cylinder could be exchanged for a more efficient Un-Vented cylinder, see enclosed notes on Un-Vented Sealed Systems.New Paragraph
For more information on different boiler types click the button below to ATAG's website. They also have a boiler finder tool to help you find the perfect boiler type for your home
