Commercial heating
What should be the deciding factors when choosing a boiler is how the heat exchanger is designed and how it integrates with other
components to achieve performance and efficiency
Examples of Potterton Commercial’s
aluminium (far right) and stainless steal boilers
protects the underlying metal. With this thin film covering the metal surface, corrosion resistance is greatly enhanced. From the manufacturing point of view, the choice of the low carbon (L) grade offers better weldability.
Aluminium
Aluminium heat exchangers have been in development for over 35 years with this being the material of choice for the first condensing boilers ever produced. This is the material that Potterton Commercial uses in its Paramount four and Eurocondense four ranges. It is a versatile material and can be cast into quite complex shapes. This enables a heat exchanger design that maximises the exchange surfaces and improves the hydraulic flow in a compact structure. As with stainless steel, the appropriate alloys play their part. In the case of heat exchangers, an aluminium-silicon alloy, or AISi, is particularly suitable. AISi alloys can cope with considerable differences in temperature to reduce damage caused by thermal shock, and they have excellent heat transfer properties. Because of this ability to conduct heat extremely efficiently, the heat exchanger can be designed to
work in a more compact boiler without reducing its heat exchange capability. Aluminium is also known for its resistance to water in a wide range of applications and is, in fact, resistant to most environments and a variety of chemical agents. Essentially, like stainless steel, aluminium develops its own protection with an inert and protective aluminium oxide film which forms on the metal surface as soon as it comes into contact with water.
Design and maintenance
While the debate surrounding materials will undoubtedly continue, it should be remembered that maintaining the quality and pH level of the water circulating through a heating system is essential. If limescale deposits itself on heat transfer surfaces, the boiler’s energy efficiency will be reduced regardless of which type of metal is used for the heat exchanger. The same goes for sludge and debris in the system. In addition to transferring thermal energy to the
system water, a condensing boiler’s heat exchanger is also used to condense exhaust gases into a liquid condensate which is mildly acidic and, therefore, corrosive. The corrosion-resistant qualities of the
heat exchanger material cannot be relied on alone to combat acidity. It is therefore important to keep the water at a pH level specified by the boiler manufacturer. The best way to maintain the right water chemistry in a heating systems is to incorporate a water treatment programme at the commissioning stage and as part of an ongoing servicing schedule. Most manufacturers’ heat exchangers are very similar in modern boilers, for the simple fact that many use common components, including heat exchangers, sourced from third-party manufacturers. Potterton Commercial, on the other hand, uses
cast aluminium heat exchangers produced in Preston, Lancashire. This allows it to control the core design of boiler parts while the design team can integrate the heat exchanger with boiler components in a way that optimises performance and space efficiency at a more competitive cost. There are merits to both stainless steel and aluminium, and maintenance matters to consider when it comes to their application as heat exchangers. What should be the deciding factors when choosing a boiler is how the heat exchanger is designed and how it integrates with other components to achieve performance and efficiency.
Potterton
know how Because we know boilers.
We’re drawing on over 150 years of boiler design and manufacture, to bring you unbeatable quality with exceptional prices. Want to know more? Visit
pottertoncommercial.co.uk
www.heatingandventilating.net Totally dependable. November 2017 25
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60
