Save significant time on in-service TMV inspections

HTM 04-01: Supplement Performance specification D 08: thermostatic mixing valves (healthcare premises) is the guidance document for thermostatic mixing valves for healthcare premises. As Haydn Newcombe, a technical consultant on sanitary fittings with over 40 years’ experience, explains, it has recently been updated in respect to in-service audit testing, with a view to simplifying the testing process, and ‘making it a little more pragmatic and a little less making onerous, while maintaining its integrity’. 

Before getting into the detail of those changes, and by way of some background to the update, the suite of Technical Memoranda, ‘HTM 04-01’, represents best practice guidance for the provision of ‘safe water in healthcare premises’. There are four documents in the suite: Part A, covering design, installation and commissioning; Part B, covering operational management, Part C, covering Pseudomonas aeruginosa – advice for augmented care units, and Part 4 – Supplement, covering the performance specification D 08: thermostatic mixing valves (healthcare). They are available to download via the GOV.UK website at: www.tinyurl.com/yc95u6bm

Parts A & B of HTM 04-01 advise that a primary water quality control is the management of water temperature within a building. Control of water temperature can help greatly in limiting the tendency of opportunistic pathogens to colonise in a water system; Legionella, for example, is known to be susceptible to colonisation in the 20˚C-45˚C temperature range. HTM 04-01 therefore requires that cold water should be maintained at <20˚C. This is not without issues, however, as it is recognised that this can sometimes prove difficult to achieve during periods of hot weather, or during times of abnormally low water demand in an underutilised building. It is also likely that there can be a seasonal temperature variation of as much as 15˚C in the cold water system. Hot water should be stored at >60˚C, distributed at >55˚C, and ≥50˚C at the calorifier return connection. The hot water system temperature can vary too, as the demand varies during the building’s daily usage cycle.