One of the most popular questions we get with all the choices available nowadays, how do we know what boilers are suitable? We are going to simplify and make sense of what you already know and need to know.
If you're just having a replacement boiler and you're happy with how warm your house is and how much hot water you get (combi boiler) then the same output (kw) boiler is perfect. The boiler model will tell you what size you have i.e. 24kw, 30kw, 34kw etc, there's usually a label found on the front or on the underside of the boiler, if you have the manufacturers manual it's in there too. It's worth bearing in mind for central heating systems that if the room feels cold while the radiator is hot all over, a bigger boiler won't make any difference as the radiator is probably undersized.
A combi is the type of boiler with the most choice from every manufacturer. Let's keep it simple the size is mainly to do with the amount of hot water you receive from your taps and shower. The more hot water you need the bigger the output (KW).
*For 2 bathrooms or more its recommended that a system boiler and unvented cylinder is fitted. From time to time we are asked to fit a 42 kw combi for 2 bathrooms or more. A really good cold water mains pressure is needed. If every bathroom is in demand at the same time the water flow to each bathroom will suffer. The maximum amount of hot water that you can receive from a combi is around 16 liters a minute, typical mixer showers use around 6.
If you have a cylinder and/or a cold water tank in the loft then you will have either a standard or a system boiler and the size you will need will depend on how much hot water your house needs from the cylinder. Generally this is how many baths and showers your property has and the boiler needs to provide for.