WATER HEATERS
“Vented heaters may be experiencing a renaissance.”
John Felgate, Head of Technical, STIEBEL ELTRON.
VENTED UNITS SAVE SPACE, ARE FASTER TO INSTALL AND CHEAPER TO BUY WITH FEWER COMPONENTS INVOLVED, SAYS STIEBEL ELTRON HEAD OF TECHNICAL JOHN FELGATE… Myth busting the performance of small water heaters
Most small water heaters sold and fitted in Ireland are of the unvented variety which require additional safety valves and expansion vessels compared to the vented type. STIEBEL ELTRON has been making water heaters for over 100 years and sells both vented and unvented heaters. Its Head of Technical John Felgate believes that, in many cases, installers may be choosing an unvented heater based on a misunderstanding over the performance of vented heaters. He points out that a huge number of unvented heaters are chosen for applications such as student accommodation where space is at a premium. Many also prioritise aesthetic considerations over cost and speed of install, with a wider range of taps available to match unvented systems. Why, in these situations, do consultants and installers continue to specify an option which is both more complicated and time consuming to install and takes up more valuable space? John, who is also chairman of the Electric Space and Water Heating group at BEAMA, said, “There’s an old
misconception that vented water heaters equal poor water pressure at the tap. This is a hangover from old-style, whole-house vented systems with header tanks in the loft that depended on gravity for their pressure at the tap. “For small-vented water heaters serving a single outlet, this isn’t a problem. They are connected to the mains so the pressure you experience at the tap is equal to your mains water pressure. The mains cold water displaces the heated water in the tank when you open the tap, forcing the water out of the tap at the same pressure.” In short, both vented and unvented small water heaters supply mains pressure at the tap. But because of this misunderstanding about vented systems necessarily providing poor water pressure, the tendency is to assume an unvented unit is the best choice even when it is easier and neater to fit vented. Vented units don’t require bulky expansion vessels and pressure relief valves, saving space. They are also faster to install and cheaper to buy with fewer components involved, particularly now that recent regulations requiring
additional relief valves have driven up the prices of regulation-compliant units. With units available for both over- and under-sink installation and with special features like STIEBEL ELTRON’s thermostop and anti-drip devices as standard, the products are now even more efficient and problem-free than ever. “Of course, there are good reasons to choose unvented systems too,” said John. “If you have more than one outlet to serve, it is easier to have one unvented heater than two or more vented units. Or, if the clients have their heart set on a particular tap for aesthetic reasons that doesn’t have a vented equivalent, and space is not an issue, unvented is again the right choice.” So next time you have a project, perhaps you will think again? With recent regulation changes requiring additional safety valves as standard, making unvented heaters more expensive to buy, vented heaters may be experiencing a renaissance. You can check out STIEBEL ELTRON’s full range of stored water heaters at: www.stiebel-eltron.ie/stored
PLUMBING & HEATING MAGAZINE | 71
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