Document name: Maintenance & Operational Procedures for the control of Legionella, water hygiene, ‘safe’ hot water, cold water, drinking water and non-drinking water. Document type
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- 3.2.2 DHW Generator Maintenance
- 3.2.3 De-stratification Checks
- 3.2.4 Domestic Hot Water Temperature Less Than 45 o C
- 3.2.4.1 Procedure for dealing with Domestic Hot Water o C
3.2 Domestic Hot Water [DHW]3.2.1 DHW Generator FlushingEach DHW generator should be flushed quarterly through its drain valve by opening the drain valve three [3] times, each time for a three [3] minute period. Precautions to be taken to minimise the release of any aerosol (i.e. direct to drain for hoses/fixed pipes). DHW generator flushing should be carried out after temperature checks on the DHW generator and system have been completed. The DHW generator blow down record sheet and DHW generator monthly temperature record sheet should be completed and returned to the Authorised Person [Water]. 3.2.2 DHW Generator MaintenanceThe cleaning procedure for DHW generator is as follows: [a] The DHW generator will be taken off line by isolating the service valves; [b] The DHW generator will be heated up until the contents have reached 70oC and held at this temperature for a period of at least one [1] hour; [c] The DHW generator will be drained. The inspection hatch will be removed. The drain down time is recorded and a photo of the internal condition is to be taken and held with the record sheet; The DHW Generator will be drained with the hose pipe outlet discharging below water level i.e. into a container of clean water. [d] The DHW Generator will then be hosed out to remove any debris, scale or other deposit. Care will be taken to ensure that aerosols are kept to a minimum; If the DHW generator does not have an inspection hatch, the pipework at the top of the vessel should be disconnected to allow the insertion of a high pressure water hose (fed from a drinking supply) to allow debris to be washed down off internal surfaces; [e] The internal and external condition of the DHW Generator and pipework should be examined, any defects should be reported immediately to the Authorised Person [Water]. The safety valve should be checked, overhauled and re-set as necessary including temperature, altitude and pressure gauges to be checked; [f] The DHW Generator can then be re-constructed, ensuring that only materials and compounds approved in the Water Fittings and Materials Directory are employed; [g] On completion of DHW generator assembly, the following sequence must be undertaken: [I] Refill with cold water; [II] Drain the DHW Generator; [III] Refill with cold water, leave cold feed valve open; [IV] Run DHW generator at a temperature of 70oC for at least one [1] hour. Test the operation of a high limit cut out system if fitted. Check the temperature of the DHW generator at the top and bottom with a touch thermometer; [V] Allow the system to cool down to the operating temperature and put the system back on line immediately. [VI] Adjust any controls as necessary; [VII] Complete DHW internal inspection record form.
Logging of DHW Generator temperatures is not undertaken in small domestic combi boiler which are single pipe water systems. 3.2.4 Domestic Hot Water Temperature Less Than 45oCThis procedure must be employed following a reduction of domestic hot water temperature to below 45oC for any reason. Such temperature reductions can result from system failures such as:
The procedure should be applied as follows:
3.2.4.1 Procedure for dealing with Domestic Hot Water <45oC[a] In the event of a reduction in domestic hot water temperature to less than 45oC, the Authorised Person [Water] be notified immediately. It may be wise to fit the DHW generator with an alarm system. This should be relatively easy to achieve for vessels on a BMS system. The reason for failure must be identified and rectified as soon as possible; [b] The Competent Person shall notify the users on the failed system that they must not draw off any hot water from the affected services until further notice; [c] The user shall ensure that their staff members are aware of the situation, and that in turn shall prevent patients from using affected services; [d] Thermal disinfection shall be carried out by raising the domestic hot water temperature of the contents of the DHW generator to 70oC, and then circulating this water throughout the affected distribution system for at least one [1] hour. Each tap or appliance should be run in sequence until full temperature is achieved [this should be measured]. To be effective the temperature in the DHW generator should be high enough to ensure that all distribution outlets receive water at a temperature of greater than 60oC. Ensure return flow to the DHW generator is a minimum of 60oC; Care must be taken not to exhaust the DHW generator during this operation. [e] The users shall be informed that the system is back in operation; [g] The Competent Person shall complete an Incident Report Form and filed in section A.4, with an entry made into the relevant Plant Room Log Book; NB – where hot water vessels are fitted with a de-stratification pump, the pump shall be running whilst thermal disinfection is taking place. This shall be stopped when the outlets are flushed. The temperatures shall be maintained 24 hours / day seven days a week. A minimum domestic hot water circulation temperature of 55oC at outlets [and inlets to TMVs] shall be maintained. Directory: documents documents -> Concept stage documents -> Concept stage documents -> The great global switch-off documents -> Nonprofit grant application documents -> The Truth about the Rwandan Genocide documents -> Annual InStructional unit plan documents -> Chaos equipment included Download 1.43 Mb. Share with your friends:
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