There are many considerations when considering whether to have a combination boiler or a standard boiler? A combination boiler gives central heating and heats water instantaneously to provide Domestic Hot Water (DHW) at the taps. This eliminates the need to have a separate DHW cylinder in an airing cupboard and so can provide space where it’s limited.
Pros: DHW is provided only when required in only the required quantity. Space is freed up where a cylinder may have been. The plumbing for the boiler is easy meaning they are often installed on new builds.
Cons: If your boiler develops a fault you will have no heating and more importantly NO Domestic Hot Water. Don’t you wish you had a cylinder so you could turn on that immersion heater?! They can be more unreliable than a standard boiler as they have more components, so more likely to go wrong. Over a long period of time they are more likely to go wrong so maintenance charges are likely to be greater.
Standard boilers use a cylinder to store an amount of DHW. They are also known as ‘heat only’ boilers.
Pros: They have relatively few components and so are inherently more reliable than a combination boiler. If they break down you will lose central heating but will still have a cylinder with immersion heater for your DHW.
Cons: They heat a large amount of water when required (normally the whole cylinder, typically 100-200 litres). The water may be greater than your needs and with cylinder heat losses you could be wasting energy.
At SHAPE Contractor we normally advise to fit a standard boiler and keep the cylinder if at all possible and room permits. We never take out a standard boiler and replace with a combi unless the client insists that is what they require or there is a combi already in place that is beyond repair.