Thanks to recent changes in the Building Regulations, with a requirement for all new boilers to have SEDBUK A or B rating, the vast majority of new domestic boilers installed in the UK in the future will be condensing. This is great news for energy efficiency but it does bring other environmental challenges.
Condensing boilers achieve higher efficiencies by condensing the moisture in the flue gases and extracting additional heat from them, while the condensed water collects as a liquid called condensate. This condensate has to be removed from the boiler, usually by discharging it to the drain using a separate condensate tube.
In this condensing process, however, flue gases such as sulphur dioxide and nitrous oxide are dissolved in the water to form sulphuric acid and nitric acid. This means that the condensate from condensing boilers is acidic and has the potential to harm the environment when it is discharged to the drain.
In referring to the strengths of acids and alkalis, the pH scale is used and this goes from 1 (strong acid) to 14 (strong alkaline) - with 7 being neutral. Condensate from condensing boilers has a pH of around 4 which, as discussed below, makes it a stronger acid than a factory would be allowed to put down the drain. At the moment, however, the environmental legislation relating to industry hasn't been applied to domestic premises.
At this point it's important to emphasise that there is no immediate danger from condensate to installers or end users - it is the cumulative effect of millions of condensing boilers that is giving cause for concern.
On average, a condensing boiler will produce 800 litres of condensate a year, at pH 4. However, around 1.6 million new domestic boilers are installed every year, so if all of these are condensing boilers, there will be an extra 1,280 million litres of acid going down our drains every year.
Eventually, as older boilers are replaced, all of the 17 million gas boilers in the UK will be condensing - so that our drainage systems will be subjected to a bombardment of 13,600 million litres (nearly 3000 million gallons) of acid each year.
Clearly, this has the potential to cause damage to the water treatment infrastructure - particularly sewage treatment works where micro-organisms such as bacteria are used to help clean the water. These micro-organisms provide a biological filter, removing impurities from the water and constitute an important stage of the water treatment process.
However, these micro-organisms are very sensitive to acid conditions and could easily be damaged by even a relatively small increase in acidity. This would have a direct impact on current sewage treatment procedures, so they would no longer be effective.
This is a problem that has already been addressed in the industrial sector, where environmental directives dictate that any effluent discharged to the sewage system must be between pH 6.5 and 8.5. As noted earlier, the pH of condensate is 4, considerably more acidic than the threshold permitted for industrial waste. So, with the rapid increase in condensing boilers in the domestic sector, it can only be a matter of time before similar restraints are imposed on condensate.
To overcome this potential problem, Salamander has developed Condensafe - a sensibly priced in-line unit designed to neutralise acidic condensate before it reaches the drains. It is fitted easily and quickly in the condensate line and changes the pH of the condensate to a suitable level.
Condensafe is suitable for use with any condensing boiler and can be fitted at any angle, so there are no additional constraints on the run of the condensate line.
Many householders are very concerned about environmental impact and will welcome the increased efficiency of condensing boilers for environmental as well as financial reasons. Those same environmentally conscious householders will be unhappy at the thought of the environmental damage their condensing boiler could cause and will be receptive to an economical solution.
From the installer's point of view this is an ideal opportunity to add value to the installation of the boiler - even before legislation is introduced to make condensate treatment compulsory. And, as the neutralising cartridge in Condensafe only requires changing every 12 months, this can be included in the annual maintenance of the system.