Genuine impartial advice for your home heating
Heat Only Boiler Guide 2020 | We Compare Prices on 67 Boiler Models
QUICK GUIDE SUMMARY
What is a heat only boiler? Who offers the best heat only boiler prices in 2020?
A heat-only boiler, aka a conventional or regular boiler, works with a hot water cylinder in the airing cupboard on an open vented (tanks in the loft) or sealed heating system. Heat only boilers can be a cost effective replacement, from £480 for a small, entry-level boiler to £1,600 for a premium model. In this guide, we compare the prices, sizes, efficiencies and warranty lengths of 67 models from 11 of the leading boiler manufacturers in the UK, including Worcester Bosch, Baxi, Ideal and Vaillant. The best heat only boiler for you will be based on your property size and your budget.
Overview of Heat Only Boilers
What is a Heat Only Boiler?
A heat only boiler provides heating and works with a cylinder to provide hot water. They can work on an open vented system (you will have tanks in loft) or sealed system. Read our Guide to Open Vented and Sealed Systems for more help.
Find your Best Heat Only Boiler
Use the tables below to find your best boiler based on price, efficiency and warranty length. For example, similarly priced boilers offer 2 and 5 year warranties; it's easy to see which one is better value!
Found your boiler? What's next?
Get an estimate of installation cost with our Boiler Quote Calculator. Are you looking for flexible ways to pay for a new boiler? Read our comprehensive guide: Ways to Pay for Your New Boiler.
How to use this Guide
Guide to using the boiler tables
Find your property size
Find your best boiler according to budget
Find your best heat only boiler
The tables are arranged so that you can easily find your property size and then find who offers the best boiler package for your budget. The tables show boiler price alongside warranty period and efficiency so you can find the best value boiler. Most boiler manufacturers produce one or two models of regular boiler with outputs between 12kW and 40KW and everything inbetween. Unlike combi and system boilers, there is not such a great disparity between prices at the lower and upper ends. That is not to say that they are all the same, we have still found great value boilers in all categories.
Best Buys and Best Performance
We have identified ‘best buys’ in each size group (highlighted yellow). These reflect an all-round great package. We have also highlighted best performance boilers (highlighted green), which are not necessarily the cheapest but offer great efficiencies and warranties.
Sizing your heat only boiler
Modern boilers are almost universally oversized. The average UK home requires just 6-8kW of heat at peak times. The most popular heat only boiler is around 15kW, more than twice the capacity most homes will ever need. So what is wrong with oversizing, just in case?
- Firstly the boiler will cycle on and off more than it was ever designed to, accelerating wear and tear.
- Secondly it will rarely operate at its most efficient, i.e. in 'condensing mode', because the return temperatures to the boiler will be too hot. Condensing boilers need the temperature of the water as it flows back to the boiler to be 50 degrees C or less. This requires a correctly sized boiler AND a perfectly balanced system with TRVs that signal the boiler to reduce its output further (modulate) as each room gets warm enough.
The good news is that most modern boilers can be 'ranged rated' down, i.e. the output reduced to more closely match your property's heat requirement, which is calculated by the attending engineer. Make sure you check that the engineer has done this. For more see our Guide to Boiler Sizing.
In some cases you will require a larger boiler however based on the capacity of your hot water cylinder coil. Coils (like an element in a kettle) may need 12kW or 25kW, depending on their size. The attending engineer will be able to assist with sizing for your hot water requirements.
Search our boiler tables
1-3 bed properties, small hot water cylinders
As outlined above, the average UK home needs 6-8kW of heat at peak times. As is evident below, it is not currently possible to buy a 6-8kW boiler, the smallest heat only boiler available is 12kW and anyway you will likely need at least 12kW for a small hot water cylinder. The good news is that you can range rate it down (see boiler sizing section above). In terms of product, the Vaillant offers the best all-round value as it goes down pretty low and comes with a 7 year warranty.
| Price | Standard warranty | Free extended warranty | Maximum heating output | Minimum heating output | ||
|---|---|---|---|---|---|---|
| Baxi 200 Heat | 12 | £600 | 3 | 3 | 13 | 7.5 |
| Baxi 400 Heat | 12 | £654 | 5 | 5 | 13 | 7.5 |
| Ideal Logic Heat | 12 | £695 | 2 | 2 | 12 | 5.1 |
| Ideal Logic + Heat | 12 | £705 | 7 | 7 | 12 | 5.1 |
| Potterton Titanium Heat | 12 | £768 | 7 | 2 | 13 | 4.3 |
| Vaillant ecoFIT pure regular
|
412 | £740 | 2 | 7 | 12 | 4.5 |
| Glow Worm Energy Regular | 12 | £740 | 7 | 7 | 12 | 4.5 |
| Vaillant ecoTEC plus regular | 412 | £805 | 5 | 10 | 12 | 4.5 |
| Worcester Bosch Greenstar Ri
|
12 | £810 | 5 | 10 | 12 | 3.4 |
| Viessmans Vitodens 100-W Regular | 13 | £850 | 5 | 10 | 13 | 7.2 |
| Viessmans Vitodens 100-W Regular | 19 | £900 | 5 | 10 | 19 | 7.2 |
| Worcester Bosch Greenstar 8000 30 | 30 | £1,275 | 5 | 10 | 30 | 3 |
2-5 bed houses, larger hot water cylinders
If you have a larger hot water cylinder then you will need a larger heat only boiler. The Vaillant and Worcester again offer the lowest minimum outputs for great all year efficiencies for a middling price.
| Price | Standard warranty | Free extended warranty | Maximum heating output | Minimum heating output | ||
|---|---|---|---|---|---|---|
| Baxi 200 Heat | 15 | £630 | 3 | 3 | 16 | 7.5 |
| Baxi 400 Heat | 15 | £685 | 5 | 5 | 16 | 7.5 |
| Main Eco Compact | 15 | £685 | 5 | 5 | 16 | 5.4 |
| Ideal Logic Heat | 15 | £720 | 2 | 2 | 15 | 5.1 |
| Ideal Logic + Heat | 15 | £740 | 7 | 7 | 15 | 5.1 |
| Glow Worm Energy Regular | 15 | £755 | 7 | 7 | 15 | 4.5 |
| Vaillant ecoFIT pure regular
|
415 | £775 | 2 | 7 | 15 | 4.5 |
| Potterton Titanium Heat | 15 | £810 | 7 | 7 | 16 | 5.4 |
| Worcester Bosch Greenstar Ri
|
15 | £830 | 5 | 10 | 15 | 4.6 |
| Viessmans Vitodens 100-W Regular | 16 | £855 | 5 | 10 | 16 | 7.2 |
| Vaillant ecoTEC plus regular | 415 | £880 | 5 | 10 | 15 | 4.5 |
| Viessmans Vitodens 100-W Regular | 19 | £900 | 5 | 10 | 19 | 7.2 |
| Worcester Bosch Greenstar 8000 30 | 30 | £1,275 | 5 | 10 | 30 | 3 |
3-5 bed houses, multiple bathrooms
Be absolutely sure that you need an 18kW boiler, it will really only be if you have multiple bathrooms. As you can see, between the 12/15kW and 18kW the minimum output jumps. The Worcester and Vaillant are still the best in the pack, although the Ideal Logic is very close and much cheaper.
| Price | Standard warranty | Free extended warranty | Maximum heating output | Minimum heating output | ||
|---|---|---|---|---|---|---|
| Baxi 200 Heat | 18 | £690 | 3 | 3 | 19 | 7.5 |
| Baxi 400 Heat | 18 | £715 | 5 | 5 | 19 | 7.5 |
| Main Eco Compact | 18 | £720 | 5 | 5 | 19 | 6.4 |
| Intergas HRE 18 | 18 | £759 | 10 | 10 | 18 | 6.1 |
| Ideal Logic Heat | 18 | £770 | 2 | 2 | 18 | 5.1 |
| Ideal Logic+ Heat | 18 | £780 | 7 | 7 | 18 | 5.1 |
| Glow Worm Energy Regular | 18 | £790 | 7 | 7 | 18 | 5.0 |
| Vaillant ecoFIT pure regular
|
418 | £845 | 2 | 7 | 19 | 5.0 |
| Potterton Titanium Heat | 18 | £850 | 7 | 7 | 19 | 6.4 |
| Worcester Bosch Greenstar Ri
|
18 | £885 | 5 | 10 | 18 | 5.5 |
| Viessmans Vitodens 100-W Regular | 19 | £900 | 5 | 10 | 19 | 7.2 |
| Vaillant ecoTEC plus regular | 418 | £965 | 5 | 10 | 19 | 5.0 |
| Worcester Bosch Greenstar 8000 30 | 30 | £1,275 | 5 | 10 | 30 | 3 |
3-5 bed houses, multiple bathrooms + very large cylinder
You are unlikely to need a 25kW boiler for your heating, but if you have a 25kW hot water cylinder coil then you will need a larger heat only boiler.
| Price | Standard warranty | Free extended warranty | Maximum heating output | Minimum heating output | ||
|---|---|---|---|---|---|---|
| Main Eco Compact 24 | 24 | £755 | 5 | 5 | 25 | 8.4 |
| Baxi 200 Heat | 24 | £755 | 3 | 3 | 21 | 7.5 |
| Baxi 400 Heat | 24 | £780 | 5 | 5 | 21 | 7.5 |
| Ideal Logic Heat | 24 | £805 | 2 | 2 | 24 | 5.1 |
| Glow Worm Energy Regular | 25 | £825 | 7 | 7 | 25 | 8.4 |
| Intergas HRE 24 | 24 | £829 | 10 | 10 | 23 | 7.7 |
| Ideal Logic + Heat | 24 | £880 | 7 | 7 | 24 | 5.1 |
| Potterton Titanium Heat | 24 | £888 | 7 | 7 | 25 | 8.4 |
| Intergas HRE 27 | 27 | £899 | 10 | 10 | 27 | 7.6 |
| Vaillant ecoFIT pure regular
|
425 | £935 | 2 | 7 | 26 | 6.1 |
| Worcester Bosch Greenstar Ri | 24 | £940 | 5 | 10 | 24 | 7.3 |
| Viessmans Vitodens 100-W Regular | 26 | £960 | 5 | 10 | 26 | 7.2 |
| Vaillant ecoTEC plus regular | 424 | £1,035 | 5 | 10 | 24 | 6.1 |
| Worcester Bosch Greenstar 8000 30
|
30 | £1,275 | 5 | 10 | 30 | 3 |
Really large hot water requirements
Very few homes every need 30kW, but large homes with multiple bathrooms in use at the same time may need 30kW for hot water. The Baxi 400 represents amazing value with a 5 year warranty. This group gets expensive quickly, but the Vaillant ecoFIT pure is still available in the mid range prices with a 7-10 year warranty when fitted by an accredited installer.
| Price | Standard warranty | Free extended warranty | Maximum heating output | Minimum heating output | ||
|---|---|---|---|---|---|---|
| Glow Worm Energy Regular | 30 | £855 | 7 | 7 | 30 | 7.5 |
| Baxi 400 Heat | 430 | £850 | 5 | 5 | 30 | 7.5 |
| Ideal Logic Heat | 30 | £910 | 2 | 2 | 30 | 6.4 |
| Vaillant ecoFIT pure regular
|
30 | £987 | 2 | 7 | 30 | 7.5 |
| Ideal Logic + Heat | 30 | £922 | 7 | 7 | 30 | 6.4 |
| Vaillant ecoTEC plus regular | 30 | £1,000 | 5 | 10 | 30 | 7.5 |
| Worcester Bosch Greenstar Ri | 30 | £1,065 | 7 | 8 | 30 | 7.0 |
| Worcester Bosch Greenstar 8000 30
|
30 | £1,275 | 5 | 10 | 30 | 3 |
Hotel sized hot water requirements
A 35kW heat only boiler will heat a huge house and is far too big for almost all UK homes, however you may need 40kW of hot water capacity if you have many bathrooms in use at once.
| Price | Standard warranty | Free extended warranty | Maximum heating output | Minimum heating output | ||
|---|---|---|---|---|---|---|
| Viessmans Vitodens 100-W Regular
|
35 | £1,290 | 5 | 10 | 35 | 7.9 |
| Vaillant ecoFIT pure regular | 35 | £1,458 | 2 | 7 | 35 | 7.5 |
| Worcester Bosch 8000 35 | 35 | £1,510 | 5 | 10 | 35 | 3.5 |
| Vaillant ecoTEC plus regular | 35 | £1,540 | 5 | 10 | 35 | 7.5 |
What is a Heat Only boiler?
A heat only boiler (also known as a Regular boiler or Conventional boiler) provides heat directly to the radiators and works with a vented hot water tank to provide hot water. Heat only boilers can work on 'open vented' or 'sealed systems' (to work out which system you have and the advantages and disadvantages of each read our Guide to Open Vented and Sealed Systems). Replacing a heat only boiler is very cost effective, however long term maintenance costs will be higher as many of the systems components (pumps, valves etc) are external to the boiler.
When is a heat only boiler right for my home?
Heat only (regular) boilers are occasionally installed in a new build home, but they are usually only a replacement for an existing heat only boiler. This is because it is more cost effective in terms of long term maintenance to install a combi or system boiler as more the system's components are integral to the boiler (pump, valves etc) and therefore covered by the manufacturer's warranty. If you are replacing your heat only boiler and considering other boiler types, the main two things to remember are 1) a heat only boiler can work on an 'open vented' system (you will have water tanks in the loft). If you wish to retain your open vented system then you will have to go with one of the heat only boilers that can work in this system configuration (see also our Guide to Open Vented and Sealed Systems). 2) If you have poor incoming water pressure then a combi or system boiler may not work. For more read our Guide to Boiler Types.
