Tens of thousands of homes have found that their newer type, condensing boiler has suddenly shut down in extremely cold weather – the Heating Helpline explains why this has happened and what homeowners can do to take preventative measures.

15 November 2011 – In each of the last two winters the UK has experienced periods of extremely cold weather with sub-zero temperatures. No one knows whether the coming winter will see a repeat of this. One unforeseen development of these extreme temperatures has been the widespread breakdown of modern condensing boilers. In its drive towards more efficient use of gas, in 2005 the Government made it mandatory for households to have condensing boilers installed, both in new build situations and when upgrading their existing heating system. At the time the Government said they would reduce a home’s carbon footprint whilst significantly cutting fuel bills. Now it is estimated there are eight million condensing boilers in homes across Britain. But tens of thousands of these homes have been left without heating over the last two winters as these boilers have shut down without warning.

Bob Towse, Technical & Safety Manager at the HVCA who run the consumer advice service the Heating Helpline, comments, “Condensing boilers recover a great deal more of the heat produced when gas is burned, to the point where some of the by-products of combustion – water vapour – condense inside the boiler and have to be disposed of. This involves an extra pipe to take the condensed water away to the property’s waste water drainage system. In some cases the routing of the pipe will involve running the pipework on the outside wall of the property and positioning the outlet over an adjacent household drain.

“The design of all of the boilers includes a safety system which shuts down the boiler in the event that the condensed water starts to ‘back-up’ inside the appliance. What has happened over the last two winters is that the condensed water has frozen in the external pipework, stopping the flow, and the safety systems within the appliance have then shut the appliance down.

“The appliance manufacturers’ instructions are very specific about the requirements for the condensate drain from their appliances and they all include the option to route the condensate drainage pipework outside the building. The installer of the equipment – and that should be a qualified Gas Safe Registered heating engineer – cannot therefore be held responsible for carrying out the installation of a condensate drain using a method specifically recommended in the installation instructions for the appliance.

“It is fair to say that when condensing boilers were being developed in the 1980s the heating industry believed that it was entering a world where winter temperatures were rising and expected to rise still further. It had been many years since the last seriously cold winter and the weather experts were warning of global temperature increases and certainly not predicting the long periods of sub-zero winter temperatures we in the UK have endured recently. External pipework routes were therefore considered acceptable as it enabled more installation options, particularly when retrofitting in existing properties.

“Of course there is nothing worse than being in the middle of a period of sub zero temperatures with a central heating boiler that doesn’t work. If these extreme winters are going to continue we can only recommend that homeowners take advice from a local Gas Safe Registered installer. The favoured options to take preventative measures are likely to be:-

-      Where possible, have the condensate pipework re-routed inside the property and connected to the property’s internal drainage system.

-      Have “trace heating” fitted to the external pipework to keep it warm.

-      Change the external pipework to one with a larger diameter – some research suggests this can reduce the risk of freezing and pipe blockage.

An easy way to locate a qualified, reputable gas installer is to use the Heating Helpline website at: or call them on 0800 840 4069. Operated by the HVCA, the Heating Helpline provides essential information on where homeowners can find a local, reputable Gas Safe Registered installer, how to employ them, how to get the best from them and what to do in the unlikely event that things do go wrong.


Issued on behalf of the HVCA by Next Step Marketing Ltd

Media enquiries to:  Heather Lambert

Tel:  44(0)1256 472020

Fax:  44(0)1256 471010


Notes to Editors

Established in 1904, the HVCA is the premier organisation representing central heating contractors across the UK, and exists to promote fair dealing and the sound installation of heating systems.  HVCA members all undergo third-party inspection and assessment of their technical competence and commercial capability every three years.  This process is carried out by an independent certification body with an established industry reputation.  HVCA members who undertake gas installations are registered with Gas Safe – the gas safety watchdog body – and are also members of TrustMark, the Government-endorsed scheme designed to direct customers towards reliable tradespeople.  HVCA operates the Heating Helpline ( to provide consumers with free, impartial advice on every aspect of home heating.


About Us

Next Step Marketing (NSM) is a marketing and communications agency based in north Hampshire. The business is headed up by Denzil Lee. Prior to setting up NSM Denzil spent 11 years as Director of Marketing for National Boat Shows Ltd (London Boat Show & Southampton Boat Show) and before that held other senior sales and marketing roles with two FTSE 100 PLCs. He has been a member of The Chartered Institute of Marketing since 1992, gaining Chartered Marketer status in June 1999. In November 2006 he was made a Fellow of the Institute. Since 1992 he has also been a member of The Marketing Society. We have worked across many different sectors with extensive experience of both consumer and B2B campaigns.




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