STEAM SYSTEMS
Effectivedomestichotwater production using steam
Instantaneous domestic hot water systems have become commonplace in our hospitals, forming the basis of design over the traditional storage calorifier. With plenty of aspects to consider to ensure such systems' maximum effectiveness and reliability, Angelo Giambrone, Regional Business Development manager for the Healthcare sector in Northern Europe at Spirax Sarco, explains why ‘looking at the bigger picture’ can help.
Over the last 20 years or so, we have seen a shift in the way that domestic hot water is produced in hospitals. Traditionally, storage calorifiers were used, consisting of a large tank capable of generating heat within a mass of water using a heat transfer coil. These can still be found, and steam is often the primary source. While this approach is familiar to many, the problem with stored hot water is that the volume continually radiates heat, which therefore limits efficiency levels, plus it can introduce a point of risk for Legionella. Storage calorifiers also take up a considerable amount of space within a plant room – important in an era when space is increasingly valued, and clinical/non-clinical space is targeted. So, how can hot water be generated on demand, without the need for stored volumes? A plate heat exchanger can deliver high levels of heat transfer within a very compact housing – generally around a third of the size of an average calorifier, or even less if the stored volume is high. It can provide rapid heat transfer, which, when combined with the latest generation of accurate control systems,
results in the ability to deliver hot water instantaneously. This eliminates the need for large quantities of hot water to be stored in calorifiers, removing the inherent standing losses, and reducing the Legionella risk.
Opportunity to modernise the cold water feed supply Another change typically associated with installing the latest in instantaneous DHW systems is that it can present an opportunity to modernise the cold water feed supply. A storage calorifier is often fed from a high-level, atmospheric, cold header tank. There is usually an expansion/vent line that runs from the calorifier to a point above the water level in the header tank. Both the header tank and the expansion line introduce points
‘‘ 82 Health Estate Journal October 2020
of risk for bacteria growth. Modernising the DHW system gives the opportunity for this to be decommissioned, in favour of a simple arrangement – directly coupling to the site’s cold water via a suitable expansion vessel and coupling system that both meet water regulations. With an understanding that hot water can now be produced at a rate to suit the demand, how are large quantities of energy distributed around site, and how do we maximise the effectiveness of the energy delivered? The typical hospital will generally have a central boiler plant feeding a network of plant rooms, covering what is often a large estate. This centralised thermal source allows for technology such as combined heat and power (CHP) to be installed. An important benefit of consolidating the thermal load
A plate heat exchanger can deliver high levels of heat transfer within a very compact housing – generally around a third of the size of an average calorifier, or even less if the stored volume is high
Spirax Sarco’s EasiHeat compact steam-to-water heat exchange packaged solution, designed to supply instantaneous domestic hot water or low temperature hot water. Steam does not require distribution pumps, eliminating the associated electrical consumption and cost that would be present with water systems.
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 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108
