The Worcester Bosch Greenstar 30i might well be one of the UK's most popular boilers, having earned money from the pockets of thousands. But so did PPI, and we all know how that ended. Important note: The Greenstar i range, which includes the 30i has now been replaced by the Worcester Bosch 4000.
Up to 10 radiators: 24–27 kW. 10 to 15 radiators: 28–34 kW. 15 to 20 radiators: 32–40 kW. Up to 10 radiators: 12–15 kW.
How Long Should a Worcester Boiler Last? Worcester Bosch boilers tend to last between 12-15 years. However, we've seen Worcester Bosch boilers that are 22+ years old and still going strong.
As a general rule of thumb, have one radiator for every 5m³ of space you need to heat.
Boiler CapacityAn easy rule-of-thumb for BTU requirements is to figure that you need about 50 BTU per square foot of interior space in a cold climate; 35 BTU per square foot in a moderate climate; and 20 BTU per square foot in a hot climate.
The main difference comes in the size of the system and the Si Compact can fit entirely within a standard kitchen cupboard making it the ideal space saver but without compromising on performance.
How to calculate what size system or regular boiler your home needs
| What size boiler for | Boiler Size Calculation | Minimum kW Size |
|---|
| 6 Radiators | 6x 1.5kW + 3kW | 12kW |
| 8 Radiators | 8x 1.5kW + 3kW | 15kW |
| 12 Radiators | 12x 1.5kW + 3kW | 21kW |
| 15 Radiators | 15x 1.5kW + 3kW | 26kW |
Boilers don't have an unlimited energy output. If there are too many radiators on a system, they will work but they won't get hot enough. It is normally ok to add one or two extra radiators, but use a BTU calculator for radiators in the home and cross reference this against the boiler output.
As a rough guide most apartments and smaller houses, with up to 10 radiators will require a 24-25kw boiler. A 28-30kw would be installed for a medium to large 3-4 bed house with up to 15 radiators, and a 33-35kw and a 40kw would be for a large house with anything up to 20 radiators.
Put simply, excessively large boilers generate too much heat that the system cannot dissipate. For example a 30kW boiler needs a flow rate of 1400 litres per hour through it.
Combi boilers provide a “combination†of instantaneous hot water and effective central heating. Therefore, the system will either transport hot water to your radiators or to your hot water tap – however, this will not be done at the same time and the hot water circuit usually takes priority.
*However combi boilers do not cope well with 2 showers running at the same time in the same property, due to the use of hot water across both showers. This is because combi boilers heat water directly from the mains when you turn on a tap.
The Blasket 21kW boiler is ideally suited for most Irish homes and is capable of heating up to 13 radiators.
As your home has four bedrooms, you'll need a boiler with an output between 27kW-40kW and a cylinder with a 250-300 litre capacity. If you have 2-3 bathrooms, you'll likely just need a 27kW system boiler, whereas a home with 3+ bathrooms will likely need a 40kW boiler.
An average three or four bedroom house typically has around ten radiators and will usually require a small or medium combi boiler, for example 24-30 kW. A larger house with substantially more radiators or an en-suite bathroom will generally need one that is larger, typically 30-35 kW.
As a basic rule, you should add 1.5 kW for every radiator in your home. For example, if you have six radiators, you should get a 9 kW electric boiler. This rule may vary depending on how high your ceilings are, whether you have single or double glazing and how effective your insulation is.
NJ Mechanical estimates that your heater should produce roughly 50 Btu per square foot to be effective. Multiply your square footage by 50 to determine the size of your boiler. For instance, if you house is 1,103 square feet, your heater should be at least 55,150 Btu.
Combi boilers need at least 10 litres per minute flow rate to operate. If you have less then you'll either need a mains pump (which can increase it to 12 litres per minute) or a pressure accumulator tank. Check with your neighbours to see if they have a combi boiler.
Best combi boiler 2021
- Best combi boiler Worcester Bosch Greenstar 2000 combi boiler.
- Best combi boiler Alpha ETec 28kW Combi Boiler.
- Best combi boiler Ideal Logic C30.
- Best combi boiler Worcester Bosch Greenstar 8000.
- Best combi boiler Viessmann Vitodens 100W 2021 model.
Worcester Bosch has a long history as being one of the best-selling and most trusted brands. Several of their combi boilers have been awarded a Which Best Buy Award for 10 consecutive years. Worcester obtained status as the best boiler brand not just through product quality, but aftercare.
Will a higher kW boiler ever cost more to run? The short answers is no. Modern boilers will fire up on a high flame, and as radiators or water reaches temperature, they'll reduce the size of the flame (modulating), then stay simmering so they aren't wasting gas.
Boiler Capacity - Engineering ToolBoxA boilers capacity is usually expressed as kBtu/hour (1000 Btu/hour) and can be calculated as. W = (hg - hf) m (1).
The 24i Combi Boiler is a high efficiency Gas Combination Boiler from Worcester, one of the UKs most popular and reliable manufacturers of boilers.
24kW ErP Condensing System BoilerWith outputs up to 24kW, the boilers are suitable for a wide range of homes. The boiler can be used with our range of high efficiency Greenstore cylinders.
During the winter, the ideal temperature setting should be 18-21 degrees. In areas that get extremely cold, then 21-23 degrees would be sufficient. If you have taken additional measures to retain heat such as wall insulation or draught-proofed windows and doors, then you could set your thermostat to 17 degrees.
I'm sorry to hear of the problems you are encountering with your Worcester Greenstar condensing boiler. We are a little confused with your comments though as the Greenstar doesn't have a pilot light, the boiler has a fully automatic ignition system.
Another potential cause of your Worcester boiler leaking water is that there could be an issue with the heat exchanger in your boiler. If it is higher than this, the boiler may be leaking to remove excess water and try to lower the pressure in the boiler. In this case, it may need 'bleeding' to remove excess water.
Turn the central heating temperature control knob fully anti- clockwise past the position. NOTE: The appliance will still operate in the domestic hot water mode. Turn the central heating temperature control knob fully anti- clockwise past the position. Switch off the electricity at the mains supply.
To reset the boiler press the reset button for approximately five seconds. When the boiler resets the reset button will no longer be illuminated. 2. The mains indicator will no longer be flashing.
There can be a number of reasons why your Worcester boiler keeps cutting out. It may be because of a faulty component, a drop in water pressure, or due to overheating. This lockout is designed to protect the overall system.
