What size boiler do I need?

QUICK GUIDE SUMMARY

How can I work out what size boiler I need?

Use our simple tables size your boiler and then find the best boiler in your size range. We have reviewed boiler models from 9 boiler manufacturers in this comprehensive guide. Sizing a combi boiler is a bit more complicated, but we offer help there too. You will of course need to get a heating engineer to visit your property to size it accurately, but this is a good start! How else can we help? We give guidance on Buying your Best Boiler.

Overview of how to size your boiler

Our tables help you size a combi, heat only or system boiler.

First decide which type of boiler you have and which type you want to install. 

Your boiler size will depend on property size,

property age, hot water requirements (combis only) and insulation levels.

If the boiler sizing table says 24kW then

you can pick a boiler from the 24-26kW bracket on the boiler tables.

HOW TO USE THIS GUIDE

Use this guide to size and find your boiler

Boiler types overview

Work out your boiler size

Find the best boiler in your size bracket

Gas Boilers by Type

Which type of gas boiler do I want? Combi, heat only or regular?

a combi boiler combines heating and hot water production in a single, usually wall hung, unit. Hot water is produced instantly when you turn the hot tap as appose to it being stored in a hot water cylinder.

a heat only boiler provides heating directly from the boiler and works with a hot water cylinder. Heat only boilers can work on open vented systems and sealed systems.

a system boiler is like a Heat Only boiler as it works with a hot water tank, however unlike a heat only boiler the pump and diverter valve are integral to the unit. System boilers are mostly found in larger newer properties with three or more bathrooms

Calculating your boiler size.

Now you know which type of boiler you require, use the tables below to work out what size boiler you need. NB this is rough guide, a heating engineer will need to properly size the boiler during a home visit.

If you have a system or regular boiler the size will be based on the heat requirements of your property. For combi boilers, the size is ‘bigger’ because it includes hot water production. There is always a temptation to oversize the boiler, just in case, but this can be very inefficient. A boiler should be sized accurately based on your house construction, i.e. insulation levels and hot water requirements.

Sizing a combi boiler

On the table below, find your property’s age across the top and its size down the left hand column. Property ages assume standard insulation measures, such as double glazing and loft insulation have been retro fitted or for newer property were installed at the time of construction. Some older properties have been very well insulated retrospectively. If your levels of insulation are very high for the property’s age, then you may wish to move a column to the right. If you are planning on adding bathrooms you will need to factor in hot water flow rates (see below).

Sizing for hot water

The hot water flow rate of a combi boiler, expressed as ‘litres per minute’ (LPM), indicates how quickly a combi boiler can heat hot water. Hot water flow rates vary from 9.8 LPM to 25 LPM! For houses with multiple bathrooms the hot water flow rate will be halved if two showers are running simultaneously so it’s important to look at the flow rates. For example, if you require a 24kW boiler, you will see that under the ’24-26kW group’ of boilers hot water flow rates vary from 9.8 LPM to 16.5 LPM. If you have multiple bathrooms you may wish to consider a boiler with a higher flow rate. NB for three or more bathrooms you may wish to consider a system boiler and high performance hot water tank.

Combi Boilers
Age of property pre 1900 1920s-1930s 1950-1980s 1990s 2000 onwards
Insulation levels Poorly insulated Some insulation Moderately insulated Reasonably insulated Well insulated
No of bedrooms and bathrooms          
1 bed + 1 bath 20kW 20kW 20kW 18kW 18kW
2 bed + 1 bath 24kW 24kW 20kW 20kW 20kW
2 bed + 2 bath 24kW 24kW 20kW 20kW 20kW
3 bed + 1 bath 28kW 28kW 26kW 24kW 24kW
3 bed + 2 bath 28kW 28kW 28kW 24kW 24kW
3 bed + 3 bath 30kW 30kW 30kW 30kW 30kW
4 bed + 1 bath 30kW 30kW 30kW 28kW 28kW
4 bed + 2 bath 32kW 32kW 32kW 30kW 30kW
4 bed + 3 bath 32kW 32kW 32kW 30kW 30kW
5 bed + 2 bath 40kW 40kW 35kW 32kW 30kW
5 bed + 3 bath 40kW 40kW 35kW 32kW 30kW
5+ bed + 3 bath 40kW 40kW 35kW 32kW 32kW

Now find the best combi boiler according to brand and budget:

Use the tables below to find a suitable model based on the size given in the table. The tables below are in size order and closely sized boilers are grouped together, say 24-26kW. If the size table above recommends at 24kW boiler for example, then all the boilers in the size group of 24-26kW are suitable.

18-19kW boilers
Manufacturer/Model Code Price Heating output (Size) Litres per minute for hot water Standard warranty Free Extended Warranty Efficiency
Glow Worm/Energy 25kW £700 18kW 10.4 2 2 89%
Ideal/Vogue C26 £1,056 18kW 10.6 10 10 91%
Vaillant/EcoFITpure 825 £865 18kW 12.1 2 7-10 89%
Vaillant/EcoTEC pro 24 £942 19kW 9.6 2 5-10 89%
Vaillant ecoTEC plus 825 £1,107 19kW >10.5 5 7-10 89%
Vaillant/EcoTEC pro 28 £984 19kW 11.1 2 5-10 89%
20-22kW boilers
Manufacturer/Model Code Price Heating output (Size) Litres per minute for hot water Standard warranty Free Extended Warranty Efficiency
Baxi/Duotec 24 £675 20kW 9.8 7 7 89%
Potterton/Titanium 24 £738 20kW 9.8 7 7 91%
Baxi/Eco Blue + Compact 24 £810 20kW 9.8 7 7 89%
Potterton/Promax 24 Plus £833 20kW 9.8 2 2 89%
Baxi Ecoblue Advance 24 £920 20kW 9.8 10 10 89%
Baxi 200 224 £629 20kW 9.8 3 3 89%
Baxi 400 424 £663 20kW 9.8 3 3 89%
Glow Worm/Easicom 24 £570 20kW 10 2 4 90%
Glow Worm/Essential 24 £618 20kW 10 3 3 89%
Potterton/Gold 24 £628 20kW 9.8 2 2 91%
Baxi 200 228 £651 20kW 11.5 5 5 89%
Baxi 400 428 £699 20kW 11.5 5 5 89%
Viessmann/Vitodens 050 29kW £827 >22kW 12.4 3 7 89%
24kW boilers
Manufacturer/Model Code Price Heating output (Size) Litres per minute for hot water Standard warranty Free Extended Warranty Efficiency
Worcester Bosch/Greenstar i 25i £875 24kW 9.8 5 7 94%
Worcestster Bosch/Si 25Si £1,010 24kW 9.8 7 9 94%
Ideal/ Logic+ Combi C24 £794 24kW 9.9 7 7 90%
Viessmann/Vitodens 100 26kW £1,050 24kW 8.9 5 10 89%
Worcester Greenstar Compact 28CDi £1,045 24kW 10.0 7 10 94%
Baxi Platinum 24 £850 24kW 9.8 10 10 89%
Ideal Independent C24 £607 24kW >9.9 5 5 89%
Ideal Independent C30 £651 24kW 12.4 5 5 89%
Glow Worm/Easicom 28 £605 24kW 11.7 2 4 90%
Ferroli/Modena 27kW £577 24kW 11.1 5 5 89%
Ideal Independent C35 £727 24kW 14.5 5 5 89%
Potterton/Gold 28 £696 24kW 13.3 2 2 91%
Baxi/Duotec 28 £795 24kW 11.5 7 7 89%
Potterton/Titanium 28 £798 24kW 11.5 7 7 91%
Worcester Bosch/Greenstar i 30i £990 24kW 11.5 5 7 94%
Worcestster Bosch/Si 30Si £1,135 24kW 11.5 7 9 94%
Baxi/Eco Blue + Compact 28 £885 24kW 11.5 7 7 89%
Vaillant/EcoTEC pro 30 £1,080 24kW 12.3 2 5-10 89%
Ideal/ Logic+ Combi C30 £830 24kW 12.4 7 7 90%
Ideal/ Logic+ Combi C35 £985 24kW 14.5 7 7 90%
Worcester Greenstar Compact 32CDi £1,140 24kW 11.5 7 10 94%
Worcester Greenstar Compact 36CDi £1,285 24kW 12.9 7 10 94%
Baxi Ecoblue Advance 28 £1,060 24kW 11.5 10 10 89%
Vaillant ecoTEC plus 832 £1,226 24kW 11.5 5 7-10 89%
Glow Worm/Easicom 28 £658 25kW 11.7 3 3 89%
Glow Worm/Ultimate 2 30 £694 25kW 12.5 5 5 89%
Glow Worm/Energy 30kW £787 25kW 12.5 2 2 89%
Glow Worm/Energy 35kW £880 25kW 14.4 2 2 89%
Glow Worm/Ultimate 2 35 £766 25kW 14.4 5 5 89%
Potterton/Promax 28 Plus £877 25kW 11.5 2 2 89%
Vaillant/EcoFITpure 830 £980 25kW 14.2 2 7-10 89%
Vaillant/EcoFITpure 835 £1,095 25kW 16.5 2 7-10 89%
Vaillant ecoTEC Green iQ 835 £1,651 25kW 14.5 5 7-10 94%
Ideal/Vogue C32 £1,245 26kW 13.1 10 10 91%
Main Eco Elite 25 £606 26kW 10.1 5 5 90%
Viessmann Vitodens 200 26kW £1,358 26kW 10.7 3 5 90%
28-29kW boilers
Manufacturer/Model Code Price Heating output (Size) Litres per minute for hot water Standard warranty Free Extended Warranty Efficiency
Viessmann/Vitodens 100 30kW £1,100 27kW 11.2 5 10 89%
Ferroli/Modena 32kW £632 28kW 13.1 5 5 89%
Potterton/Gold 33 £764 28kW 15.7 2 2 91%
Baxi/Duotec 33 £915 28kW 13.5 7 7 89%
Potterton/Titanium 33 £858 28kW 13.5 7 7 91%
Baxi/Eco Blue + Compact 33 £955 28kW 13.5 7 7 89%
Baxi Platinum 28 £955 28kW 11.5 10 10 89%
Baxi Ecoblue Advance 33 £1,175 28kW 13.5 10 10 89%
Potterton/Promax 33 Plus £1,045 29kW 13.5 2 2 89%
Vaillant ecoTEC plus 838 £1,394 29kW 15.9 5 7-10 89%
30kw boilers
Manufacturer/Model Code Price Heating output (Size) Litres per minute for hot water Standard warranty Free Extended Warranty Efficiency
Worcester Greenstar Classic 29CDi £1,100 30kW 11.0 7 10 92%
Worcester Greenstar Classic 34CDi £1,225 30kW 12.0 7 10 92%
Viessmann Vitodens 200 30kW £1,435 30kW 12.3 3 5 90%
Main Eco Elite 30 £668 30kW 12.3 5 5 88%
Viessmann/Vitodens 050 35kW £906 30kW 14.5 3 7 89%
Worcester Greenstar Classic 38CDi £1,395 30kW 4 7 10 92%
Vaillant ecoTEC plus 835 £1,110 30kW 14.3 5 7-10 89%
Worcester Greenstar Classic 42CDi £1,665 30kW 15.0 7 10 92%
32kW boilers
Manufacturer/Model Code Price Heating output (Size) Litres per minute for hot water Standard warranty Free Extended Warranty Efficiency
Baxi/Duotec 40 £985 32kW 16.4 7 7 89%
Potterton/Titanium 40 £930 32kW 16.4 7 7 91%
Viessmann/Vitodens 100 35kW £1,160 32kW 13.5 5 10 89%
Baxi Ecoblue Advance 40 £1,240 32kW 16.4 10 10 89%
Ideal/Vogue C40 £1,390 32kW 16.4 10 10 91%
Baxi Platinum 33 £1,110 33kW 13.5 10 10 89%
Vaillant ecoTEC Green iQ 843 £1,979 33kW 17.8 5 7-10 94%
Ferroli/Modena 38kW £764 34kW 16 5 5 89%
35-40kW boilers
Manufacturer/Model Code Price Heating output (Size) Litres per minute for hot water Standard warranty Free Extended Warranty Efficiency
Viessmann Vitodens 200 35kW £1,620 35kW 14.3 3 5 90%
Baxi Platinum 40 £1,225 40kW 16.4 10 10 89%

Sizing a heat only boiler

For a heat only boiler we are only sizing the heat production, not the hot water. It is possible to get a rough idea of the size you need using the age of your property, insulation levels and the size of your property. Property ages are given across the top and they assume standard insulation measures, such as double glazing and loft insulation, have been made. If your levels of insulation are uncharacteristically high for the age of the property then you may wish to move a column to the right.

Heat Only Boilers
Age of property pre 1900 1920s-1930s 1950-1980s 1990s 2000 onwards
Insulation levels Poorly insulated Some insulation Moderately insulated Reasonably insulated Well insulated
Number of bedrooms          
1 15kW 13kW 12kW 12kW 12kW
2 18kW 16kW 15kW 15kW 13kW
3 21kW 20kW 18kW 16kW 15kW
4 24kW 22kW 20kW 18kW 16kW
5 35kW 30kW 24kW 20kW 18kW
5+ 41kW 35kW 30kW 25kW 21kW

Now find the best heat only boiler according to brand and budget:

Use the tables below to find a suitable model. The tables are ordered in according to size and closely sized boilers are grouped together in a size bracket, for example 18-21kW. If the sizing table indicates an 18kW boiler for example, then all the boilers in the size group of 18-21kW are applicable.

12-13kW boilers
12-13kW Code Price Central heating output Standard warranty Free extended warranty Efficiency
Main heat only boiler 12 £480.00 12kW 2 2 89%
Potterton Promax SL Heat 12 £674.00 12kW 2 2 89%
Ideal Logic Heat 12 £695.00 12kW 2 2 89%
Vaillant ecoFIT pure regular 12 £702.00 12kW 2 7-10 89%
Glow Worm Energy Regular 12 £704.00 12kW 2 2 89%
Vaillant ecoTEC plus regular 12 £730.00 12kW 5 7-10 89%
Ideal Logic + Heat 12 £765.00 12kW 7 7 89%
Worcester Bosch Greenstar Ri 12 £786.00 12kW 7 8 91%
Baxi 200 Heat 12 £653.00 13kW 3 3 89%
Baxi 400 Heat 12 £669.00 13kW 5 5 89%
Baxi Ecoblue Advance Heat 13 £776.00 13kW 7 7 89%
Baxi Ecoblue Heat 12 £795.00 13kW 2 2 89%
Viessmans Vitodens 100-W Regular 13 £816.00 13kW 5 5 90%
15-16kW boilers
15-16kW Code Price Central heating output Standard warranty Free extended warranty Efficiency
Main heat only boiler 15 £505.00 15kW 2 2 89%
Glow Worm Energy Regular 15 £722.00 15kW 2 2 89%
Ideal Logic Heat 15 £730.00 15kW 2 2 89%
Vaillant ecoFIT pure regular 15 £733.00 15kW 2 7-10 89%
Potterton Promax SL Heat 15 £751.00 15kW 2 2 89%
Ideal Logic + Heat 15 £796.00 15kW 7 7 89%
Worcester Bosch Greenstar Ri 15 £801.00 15kW 7 8 91%
Vaillant ecoTEC plus regular 15 £822.00 15kW 5 7-10 89%
Baxi 200 Heat 15 £677.00 16kW 3 3 89%
Baxi 400 Heat 15 £691.00 16kW 5 5 89%
Viessmans Vitodens 100-W Regular 16 £841.00 16kW 5 5 90%
Baxi Ecoblue Heat 15 £843.00 16kW 2 2 89%
Baxi Ecoblue Advance Heat 16 £855.00 16kW 7 7 89%
18-21kW boilers
18-21kW Code Price Central heating output Standard warranty Free extended warranty Efficiency
Main heat only boiler 18 £539.00 18kW 2 2 89%
Glow Worm Energy Regular 18 £755.00 18kW 2 2 89%
Ideal Logic Heat 18 £763.00 18kW 2 2 89%
Potterton Promax SL Heat 18 £780.00 18kW 2 2 89%
Vaillant ecoFIT pure regular 18 £802.00 18kW 2 7-10 89%
Worcester Bosch Greenstar Ri 18 £859.00 18kW 7 8 91%
Vaillant ecoTEC plus regular 18 £894.00 18kW 5 7-10 89%
Baxi 200 Heat 18 £708.00 19kW 3 3 89%
Baxi 400 Heat 18 £720.00 19kW 5 5 89%
Baxi Ecoblue Heat 18 £860.00 19kW 2 2 89%
Baxi Ecoblue Advance Heat 19 £908.00 19kW 7 7 89%
Viessmans Vitodens 100-W Regular 19 £858.00 19kW 5 5 90%
Baxi 200 Heat 24 £749.00 21kW 3 3 89%
Baxi Ecoblue Heat 21 £913.00 21kW 2 2 89%
22-24kW boilers
22-24kW Code Price Central heating output Standard warranty Free extended warranty Efficiency
Potterton Promax SL Heat 24 £822.00 22kW 2 2 89%
Main heat only boiler 24 £593.00 24kW 2 2 89%
Ideal Logic Heat 24 £796.00 24kW 2 2 89%
Ideal Logic + Heat 24 £828.00 24kW 7 7 89%
Worcester Bosch Greenstar Ri 24 £909.00 24kW 7 8 92%
Vaillant ecoTEC plus regular 24 £959.00 24kW 5 7-10 89%
25-27kW boilers
25-27kW Code Price Central heating output Standard warranty Free extended warranty Efficiency
Baxi 200 Heat 30 £756.00 25kW 3 3 89%
Baxi 400 Heat 24 £763.00 25kW 5 5 89%
Glow Worm Energy Regular 24 £788.00 25kW 2 2 89%
Vaillant ecoFIT pure regular 25 £874.00 25kW 2 7-10 89%
Baxi Ecoblue Heat 24 £1,103.00 25kW 2 2 89%
Baxi Ecoblue Advance Heat 25 £925.00 25kW 7 7 89%
Viessmans Vitodens 100-W Regular 26 £915.00 26kW 5 5 90%
Worcester Bosch Greenstar Ri 27 £1,021.00 27kW 7 8 92%
30kW boilers
30kW Code Price Central heating output Standard warranty Free extended warranty Efficiency
Glow Worm Energy Regular 30 £826.00 30kW 2 2 89%
Baxi 400 Heat 30 £834.00 30kW 5 5 89%
Ideal Logic Heat 30 £905.00 30kW 2 2 89%
Vaillant ecoFIT pure regular 30 £932.00 30kW 2 7-10 89%
Baxi Ecoblue Advance Heat 30 £981.00 30kW 7 7 89%
Ideal Logic + Heat 30 £889.00 30kW 7 7 89%
Vaillant ecoTEC plus regular 30 £1,000.00 30kW 5 7-10 89%
Worcester Bosch Greenstar Ri 30 £1,065.00 30kW 7 8 93%
Worcester Bosch Greenstar Classic Cdi 30 £1,141.00 30kW 7 10 92%
35kW - 41kW boilers
35kW- 41kW Code Price Central heating output Standard warranty Free extended warranty Efficiency
Viessmans Vitodens 100-W Regular 35 £1,325.00 35kW 5 5 90%
Vaillant ecoFIT pure regular 35 £1,449.00 35kW 2 7-10 89%
Vaillant ecoTEC plus regular 35 £1,535.00 35kW 5 7-10 89%
Worcester Bosch Greenstar Classic Cdi 40 £1,589.00 41kW 7 10 92%

Sizing a system boiler

A system boiler is sized for heating only. If you house has seen standard levels of insulation improvements, such as loft insulation or double glazing, then go with the applicable age bracket. If the insulation levels are particularly high relative to its age then move one column to the right.

System Boilers
Age of property pre 1900 1920s-1930s 1950-1980s 1990s 2000 onwards
Insulation levels Poorly insulated Some insulation Moderately insulated Reasonably insulated Well insulated
Number of bedrooms          
1 15kW 15kW 12kW 12kW 12kW
2 18kW 18kW 15kW 15kW 12kW
3 20kW 20kW 18kW 18kW 15kW
4 24kW 24kW 20kW 18kW 18kW
5 35kW 30kW 24kW 20kW 18kW
5+ 37kW 35kW 30kW 25kW 20kW

Now find the best system boiler according to brand and budget:

Now use the tables below to find the best boiler based on your required size. The tables are in size order and closely sized boilers are grouped together, for example 24-26kW. If the sizing table recommends a 24kW boiler for example, then all the boilers in the size group of 24-26kW are applicable.

12-13kW boilers
12-13kW Code Price Central heating output Standard warranty Free extended warranty Efficiency
Glow Worm Energy System 12 £712 12kW 2 2 89%
Vaillant ecoTEC plus system 12 £772 12kW 5 7-10 89%
Potterton Promax System 12 £794 12kW 2 2 89%
Vaillant ecoFIT pure system 12 £812 12kW 2 7-10 89%
Worcester Bosch Greenstar System i 12 £879 12kW 7 8 94%
Baxi Ecoblue System 12 £901 13kW 7 7 89%
15-17kW boilers
15-17kW Code Price Central heating output Standard warranty Free extended warranty Efficiency
Glow Worm Energy System 15 £731.00 15kW 2 2 89%
Ideal Logic System 15 £741.00 15kW 2 2 89%
Potterton Promax System 15 £808.00 15kW 2 2 89%
Ideal Logic + System 15 £809.00 15kW 7 7 89%
Vaillant ecoTEC plus system 15 £858.00 15kW 5 7-10 89%
Vaillant ecoFIT pure system 15 £875.00 15kW 2 7-10 89%
Worcester Bosch Greenstar System i 15 £926.00 15kW 7 8 94%
Ideal Vogue System 15 £944.00 15kW 8 10 93%
Baxi Ecoblue System 15 £923.00 17kW 7 7 89%
Ferroli Modena HE 18S 18 £575.00 17kW 5 5 89%
18-21kW boilers
18-21kW Code Price Central heating output Standard warranty Free extended warranty Efficiency
Potterton Gold System 18 £566.00 18kW 2 2 88%
Glow Worm Energy System 18 £757.00 18kW 2 2 89%
Ideal Logic System 18 £810.00 18kW 2 2 89%
Potterton Promax System 18 £825.00 18kW 2 2 89%
Ideal Logic + System 18 £841.00 18kW 7 7 89%
Vaillant ecoFIT pure system 18 £931.00 18kW 2 7-10 89%
Vaillant ecoTEC plus system 18 £954.00 18kW 5 7-10 89%
Worcester Bosch Greenstar System i 18i £974.00 18kW 7 8 94%
Ideal Vogue System 18 £1,015.00 18kW 8 10 93%
Viessmann 100-W System 19 £1,032.00 19kW 5 5 90%
Viessmann 200-W System 19 £1,296.00 19kW 5 5 90%
Baxi Ecoblue System 18 £962.00 20kW 7 7 89%
Worcester Bosch Greenstar System i 21 £1,014.00 21kW 7 8 94%
24-24kW boilers
24-25kW Code Price Central heating output Standard warranty Free extended warranty Efficiency
Potterton Gold System 21 £589.00 24kW 2 2 88%
Ideal Logic System 24 £844.00 24kW 2 2 89%
Ideal Logic + System 24 £872.00 24kW 7 7 89%
Worcester Bosch Greenstar System i 24i £1,035.00 24kW 7 8 94%
Vaillant ecoTEC plus system 24 £1,137.00 24kW 5 7-10 89%
Ferroli Modena HE 25S 25 £588.00 25kW 5 5 89%
Glow Worm Energy System 25 £809.00 25kW 2 2 89%
Potterton Promax System 24 £863.00 25kW 2 2 89%
Vaillant ecoFIT pure system 25 £1,100.00 25kW 2 7-10 89%
Main System Eco Elite 24 £617.00 26kW 3 3 92%
Viessmann 100-W System 26 £1,068.00 26kW 5 5 90%
Ideal Vogue System 26 £1,169.00 26kW 8 10 93%
Viessmann 200-W System 26 £1,410.00 26kW 5 5 90%
26-29kW boilers
26-29kW Code Price Central heating output Standard warranty Free extended warranty Efficiency
Worcester Bosch Greenstar System i 27i £1,042.00 27kW 7 8 92%
Baxi Ecoblue System 24 £1,053.00 27kW 7 7 89%
Vaillant ecoTEC exclusive 27 £1,438.00 27kW 5 7-10 90%
Potterton Gold System 24 £609.00 28kW 2 2 88%
Main System Eco Elite 28 £680.00 29kW 3 3 92%
30-32kW boilers
30-32kW Code Price Central heating output Standard warranty Free extended warranty Efficiency
Glow Worm Energy System 30 £833.00 30kW 2 2 89%
Ideal Logic System 30 £877.00 30kW 2 2 89%
Ideal Logic + System 30 £902.00 30kW 7 7 89%
Viessmann 100-W System 30 £1,100.00 30kW 5 5 90%
Worcester Bosch Greenstar System i 30i £1,112.00 30kW 7 8 92%
Worcester Bosch Greenstar System Cdi 30 £1,132.00 30kW 7 10 92%
Vaillant ecoTEC plus system 30 £1,173.00 30kW 5 7-10 89%
Vaillant ecoFIT pure system 30 £1,207.00 30kW 2 7-10 89%
Viessmann 200-W System 30 £1,519.00 30kW 5 5 90%
Ferroli Modena HE 32S 32 £669.00 31kW 5 5 89%
Baxi Ecoblue System 28 £1,087.00 31kW 7 7 89%
Ideal Vogue System 32 £1,256.00 32kW 8 10 93%
34-37kW boilers
34-37kW Code Price Central heating output Standard warranty Free extended warranty Efficiency
Potterton Promax System 32 £948.00 34kW 2 2 89%
Worcester Bosch Greenstar System CDI 35 £1,245.00 34kW 7 10 92%
Baxi Ecoblue System 30 £1,137.00 35kW 7 7 89%
Viessmann 100-W System 35 £1,511.00 35kW 5 5 90%
Viessmann 200-W System 35 £1,571.00 35kW 5 5 90%
Vaillant ecoTEC plus system 37 £1,312.00 37kW 5 7-10 89%

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