Condensing boilers are no longer news. They first appeared in the 1980s and for years were known as energy-saving boilers. They work by having a secondary heat exchanger which is used to take a load of heat out of the flue gases from the main boiler. This makes them more expensive to build and a little more expensive to install. Hence, they were seen as something of a green curio, an expensive option for those who cared about the planet, or the size of their gas bills. By 2004, they had achieved a market penetration of just 3%. Although a condensing boiler could be shown to have a very short payback (less than 5 years), people didn't want to spend an extra £250 for a condenser.
But then the building regs changed. In April 2005, Part L (England & Wales) was amended to make condensing boilers all but compulsory. Today, condensing boilers have over 95% of the new boiler market. That, ladies and gentlemen, is a prime example of government intervention raising the bar. What is more, you can source an A-rated Baxi Solo condensing boiler for just £450 (plus VAT). We were paying that much for ordinary boilers back in the 1990s. So competition and economies of scale have eroded the price differential (though some cynics will argue that quality has also been engineered out).
All in all, it makes a powerful argument in favour of legislation as the best way of increasing energy efficiency. If condensers hadn't been made compulsory, I bet that they would still cost £250 more and that market penetration would be sticky at around 3%.
Which brings me on to Zenex's Gas Saver. This is a new(isn) device which you attach to a condensing gas boiler and it draws even more heat from the flue gases and uses it to pre-heat the water going into the boiler. It is, if you like, a tertiary heat exchanger. The generic name for this is Passive Flue Gas Heat Recovery Devices (PFGHRDs) and the inventor, Chris Farrell, started Zenex to develop and market it.
In some ways, it's been a splendid success. Fitting a PFGHRD to a boiler has been demonstrated to bring about gas savings of up to 40% for hot water generation and consequently PFGHRDs are a ground-breaking British technology, recognised in Building Regulations, recommended by the Energy Saving Trust and recognised in the Green Deal.
Better still, two of our major boiler manufacturers, Baxi and Alpha, now market Zenex's Gas Saver with their own offerings. Indeed Alpha have a built-in version (The In Tec GS) so that you can install the boiler and the Gas saver in just one box.
But the Gas Saver costs. On it's own, it's over £600 to buy. Coupled with an Alpha boiler, it doubles the price of the boiler. And just like the condensing boiler pre 2005, it has a tiny market penetration. There are around 1.5million new boilers fitted in the UK each year (about 90% of these are replacements) and only a tiny fraction have Gas Savers fitted to them.
How best to change this situation? Though the savings appear to be real enough, and the payback period is again probably less than five years, the uplift in price between a condensing boiler and a condensing boiler plus Gas Saver is enough to put most casual buyers off — that's if they ever get to hear about it in the first place. Maybe the Green Deal will come into its own here, as PFGHRDs appear to meet the Golden Rule. But I can't help feeling that the answer lies in building regs enforcement.