Guide to choosing a new boiler
Since 2005 all new boilers installed have to be “condensing” boilers in line with Government regulations because they have higher energy efficiency.
A condensing boiler is the most energy efficient type of boiler currently available, with 90% efficiency compared to 55% efficiency on older, non condensing boilers. That’s a potential saving of 35p for every £1 spent on heating the boiler!
Condensing Boiler Types
Combination boilers provide your heating and hot water without a hot water tank. The heat exchanger, which is incorporated into the boiler casing, heats up the domestic hot water on demand. You will not, therefore, waste energy and money heating a tank of water that you may not use. Combination boilers are so called because they combine the traditional capabilities of a standard central heating boiler with the added functionality of being able to utilize the full boiler capacity to heat water instantaneously.
- Suitable for smaller flats or houses
- Often cost less to install than conventional boilers and can cause less disturbance during installation
- The space a hot water tank and cold header tank would have occupied can be utilised for a different purpose
- Saving on all fuel costs
- All cold outlets are potable drinking water
- The hot water delivery rate may be slower
- Diminished flow rate if two taps are run at the same time
- An electric immersion heater cannot be installed as a back up
- Installation is more expensive if you already have a hot water tank
System (Gravity) Boilers
The conventional boiler system works by storing hot water in a separate cylinder tank. Hot water is then pumped throughout the house heating the radiators. Water is heated either directly in the storage cylinder, for example by an electric immersion heater or from a remote boiler. The two main types of system are the open vented and the unvented.
The open vented water system relies on a large volume of stored water, usually located in a plastic water tank in the attic. The weight of stored water is usually sufficient to push water down the pipe that feeds the water storage cylinder and back up to any tap or shower outlet, providing it is lower than the stored water level.
The unvented stored water system (for example Megaflo cylinders) in general terms rely on mains water pressure to push the water out of the cylinder or through the pipe circuit to the trap or shower outlet. This provides a system of high pressure water.
- High flow rates depending on height of stored water or mains pressure
- Power shower capability depending on choice of cylinder
- Low maintenance costs, especially with electric heating
- Gain the traditional airing cupboard
- Less risk of being without a hot water supply due to breakdown
- Regular maintenance required on unvented units (such as Megaflo)
- Need to pre- heat hot water to match demand
- Hot water availability is restricted by the heat recovery time period and size of cylinder
- Require storage tanks and space
- Risk of pipes freezing in the winter