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Great Home

Independent Advice On Improving Your Home

Gas Heat Only Boilers

Grundfos ALPHA2 Central Heating Pump
Grundfos ALPHA2 Central Heating Pump

Gas heat only boilers, also sometimes known as open vent boilers, provide heat to radiators and a hot water cylinder. Hot water is heated over a period of time and then stored in a hot water cylinder for use when needed, unlike a combi boiler which heats water instantaneously. As a result heat only boilers generally require less power output than a combi; a typical heat only boiler will be 15-20kW output rather than a minimum of 24kW output for a combi. Heat only boilers are also generally simpler and lower priced than system boilers. A system boiler has additional components built into the unit whereas a heat only boiler relies on external components such as a pump to circulate water round the system.

The choice between an heat only boiler or a system boiler is often driven by ease of installation. In an existing installation where the existing external components, such as the Grundfos pump shown in the photo, do not require replacement then a heat only boiler is a lower cost choice. System boilers have not been around so long so most existing installations will be using a heat only boiler. Where a totally new installation is being done then a system boiler may make more sense as the installer does not have to buy or install additional components.

Below we list the popular heat only boiler options by power output in kW and then brand. Note that the prices are for the boiler only and do not include the flue. They are also typical prices and do not reflect any price promotions with a specific plumbers merchant or retailer. On occasions, manufacturers offer promotional packages which include the flue.

See also prices for: System Boilers and Combi Boilers.

If you want an indication of what you may pay for a boiler replacement including installation then use our replacement boiler cost online calculator. You can then compare any quotations from installers with this guideline estimate.

Power
Output
ProductTypical price
inc VAT
Warranty
Period
Years *
Technical
Details
9kWWorcester Bosch Greenstar 9Ri£887.295View
12kWBaxi 200 Heat 12£766.783View
12kWBaxi 400 Heat 12£785.563View
12kWGlow-worm Energy 12kW regular£786.997View
12kWIdeal Logic Heat H12£729.212View
12kWIdeal Logic Max Heat H12£874.9910View
12kWIdeal Logic+ Plus Heat H12£768.357View
12kWPotterton Titanium 12 heat£734.507View
12kWVaillant ecoFIT pure 412 regular£767.602View
12kWVaillant ecoTEC plus 412 regular boiler£822.915View
12kWWorcester Bosch Greenstar 12Ri£851.245View
15kWBaxi 200 Heat 15£801.483View
15kWBaxi 400 Heat 15£810.135View
15kWGlow-worm Energy 15kW regular£806.787View
15kWIdeal Logic+ Plus Heat H15£878.737View
15kWIdeal Logic Heat H15£766.752View
15kWIdeal Mexico HE 15£1,130.112View
15kWIdeal Logic Max Heat H15£961.2510View
15kWPotterton Titanium 15 heat£773.507View
15kWVaillant ecoTEC plus 415 regular boiler£882.295View
15kWVaillant ecoFIT pure 415 regular£802.062View
15kWWorcester Bosch Greenstar 15Ri£857.235View
18kWBaxi 400 Heat 18£844.415View
18kWBaxi 200 Heat 18£786.253View
18kWGlow-worm Energy 18kW regular£847.997View
18kWIdeal Mexico HE 18£1,221.852View
18kWIdeal Logic Heat H18£799.482View
18kWIdeal Logic+ Plus Heat H18£835.047View
18kWIdeal Logic Max Heat H18£951.0410View
18kWPotterton Titanium 18 heat£812.507View
18kWVaillant ecoTEC plus 418 regular boiler£993.735View
18kWVaillant ecoFIT pure 418 regular£876.042View
18kWWorcester Bosch Greenstar 18Ri£917.755View
21kWWorcester Bosch Greenstar 21Ri£1,028.885View
24kWBaxi 200 Heat 24£875.713View
24kWBaxi 400 Heat 24£899.495View
24kWIdeal Logic Heat H24£837.562View
24kWIdeal Mexico HE 24£1,688.562View
24kWIdeal Logic Max Heat H24£985.4610View
24kWIdeal Logic+ Plus Heat H24£875.467View
24kWPotterton Titanium 24 heat£851.507View
24kWVaillant ecoTEC plus 424 regular boiler£1,055.195View
24kWWorcester Bosch Greenstar 24Ri£972.355View
25kWGlow-worm Ultimate 3 25kW regular£802.945View
25kWGlow-worm Energy 25kW regular£883.997View
25kWVaillant ecoFIT pure 425 regular£952.062View
27kWWorcester Bosch Greenstar 27Ri£1,090.695View
30kWBaxi 200 Heat 30£893.943View
30kWBaxi 400 Heat 30£976.505View
30kWGlow-worm Energy 30kW regular£927.937View
30kWIdeal Mexico HE 30£2,074.002View
30kWIdeal Logic Heat H30£953.232View
30kWIdeal Logic Max Heat H30£1,156.2510View
30kWIdeal Logic+ Plus Heat H30£993.307View
30kWVaillant ecoFIT pure 430 regular£1,012.482View
30kWVaillant ecoTEC plus 430 regular boiler£1,109.355View
30kWWorcester Bosch Greenstar FS 30CDi Regular£1,732.885View
30kWWorcester Bosch Greenstar 30Ri£1,136.605View
30kWWorcester Bosch Greenstar 30CDi Classic Regular£1,216.285View
32kWPotterton Titanium 32 heat£877.507View
35kWVaillant ecoFIT pure 435 regular£1,495.812View
35kWVaillant ecoTEC plus 435 regular boiler£1,597.915View
36kWIdeal Mexico HE 36£2,857.162View
40kWWorcester Bosch Greenstar 40CDi Classic Regular£1,690.985View
42kWWorcester Bosch Greenstar FS 42CDi Regular£2,363.595View

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Jon Davies

Hi I'm Jon. This website seeks to help those searching for the basics about improving their home. It offers an independent view, trying to balance the interests of … read more

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