-SQA- SCOTTISH QUALIFICATIONS AUTHORITY. Hanover House 24 Douglas Street GLASGOW G2 7NQ NATIONAL CERTIFICATE MODULE DESCRIPTOR

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1 -SQA- SCOTTISH QUALIFICATIONS AUTHORITY Hanover House 24 Douglas Street GLASGOW G2 7NQ NATIONAL CERTIFICATE MODULE DESCRIPTOR -Module Number Session Superclass- TH -Title- PLUMBING: MAINS-FED HOT WATER SYSTEMS -DESCRIPTION- Purpose This module is designed to introduce the student to the operating principles and pipework arrangements of mains-fed hot water systems and to maintenance procedures. It is aimed at those following a career in plumbing and receiving complementary industrial experience. Preferred Plumbing: Hot Water Systems-1 (x 1/2) Entry Level Plumbing: Hot Water Systems-2 Outcomes The student should: 1. outline the principles of operation and installation requirements of instantaneous and low storage capacity mains-fed water heaters; 2. outline the pipework arrangements and installation requirements for domestic storage mains-fed (unvented) hot water supply systems; 3. describe the functions of components, valves and pipework for storage mains-fed (unvented) hot water supply systems; 4. describe the remedial action necessary to rectify specific malfunctions in a domestic mains-fed (unvented) hot water system. Assessment Procedures Acceptable performance in the module will be satisfactory achievement of all the Performance Criteria specified for each Outcome.

2 The following abbreviations are used below: PC Performance Criteria Instrument of Assessment Note: The Outcomes and PCs are mandatory and cannot be altered. The may be altered by arrangement with SQA. (Where a range of performance is indicated, this should be regarded as an extension of the PCs and is therefore mandatory.) OUTCOME 1 OUTLINE THE PRINCIPLES OF OPERATION AND INSTALLATION REQUIREMENTS OF INSTANTANEOUS AND LOW STORAGE CAPACITY MAINS-FED WATER HEATERS PCs (a) The outline is correct in terms of: (i) the quantity and flow-rate of water; (ii) the position and type of sanitary appliance(s) served; (iii) the safe operation of the heater. (b) The outline is in accordance with the manufacturers' instructions and the current appropriate regulations. Assignment The student will be set an assignment to test the knowledge required to outline the principles of operation and installation requirements of instantaneous and low storage capacity mains-fed water heaters. The student will be presented with an A4 size scale drawing of a dwelling which incorporates: (i) (ii) a group of sanitary appliances; an isolated sanitary appliance; both situations requiring hot water supply. The position of the mains cold water supply and the inlet pressure, as well as the fuel power source will be indicated. Manufacturers' literature on water heaters will be made available. The student will be required to select appropriate water heaters and produce a fully annotated drawing, showing the position of heaters and the pipework arrangements. The student will also be required to state the operating principles and detail the installation requirements for each heater

3 on the student attaining all the Performance Criteria. OUTCOME 2 OUTLINE THE PIPEWORK ARRANGEMENTS AND INSTALLATION REQUIREMENTS FOR DOMESTIC STORAGE MAINS-FED (UNVENTED) HOT WATER SUPPLY SYSTEMS PCs (a) The pipework arrangements are correct in terms of connection to components, valves and appliances. (b) The location of the components, pipework and valves is correct in terms of the system performance. (c) The identification of the components, pipework and valves is clear and in accordance with accepted terminology. (d) The outline is in accordance with the current appropriate regulations. (e) The outline is correct in terms of safe operation and prevention of contamination and misuse. Assignment The student will be set an assignment to test the knowledge required to outline the pipework arrangements and installation requirements for domestic storage mains-fed (unvented) hot water supply systems. The student will be provided with an elevational drawing of A3 size showing the following components: an unvented indirect cylinder, an oil or gas-fired boiler, a feed and expansion cistern with an open vent, feed and expansion pipework to the boiler, and the draw-off points for a group of sanitary appliances (including a shower) requiring a balanced hot and cold water supply. The student will be required to complete and annotate the drawing, showing the pipework layout and all necessary valves and controls for the situation given. on the student attaining all the Performance Criteria

4 OUTCOME 3 DESCRIBE THE FUNCTION OF COMPONENTS, VALVES AND PIPEWORK FOR STORAGE MAINS-FED (UNVENTED) HOT WATER SUPPLY SYSTEMS PCs (a) The described functions of components, valves and pipework are correct in terms of: (i) (ii) (iii) (iv) (iv) provision for expansion of water; temperature control; backflow-contamination prevention; regulating water pressures; straining of water. Objective Items The student will be presented with an exercise consisting of objective items to test the recall of knowledge required to describe the functions of components, valves and pipework for storage mains fed (unvented) hot water supply systems. The exercise will consist of 8 questions as follows: (a) provision for expansion of water - 2 (b) temperature control - 3 (c) backflow-contamination prevention - 1 (d) regulating water pressures - 1 (e) straining of water - 1 Objective items could be either short answer questions, multiple choice questions, a matching exercise, a grid exercise or a completion exercise. on the student attaining all the Performance Criteria. This will be demonstrated by the student producing correct responses to each part. OUTCOME 4 DESCRIBE THE REMEDL ACTION NECESSARY TO RECTIFY SPECIFIC MALFUNCTIONS IN A DOMESTIC MAINS-FED (UNVENTED) HOT WATER SYSTEM PCs (a) The remedial action described is correct in terms of diagnosis of fault(s). (b) The remedial action described is economical. (c) The remedial action described is correct in terms of safe operation of the system

5 Restricted Response The student will be set an exercise of restricted response questions to test the knowledge required to describe the remedial action necessary to rectify specific malfunctions in a domestic mains fed (unvented) hot water storage system. The exercise will consist of 3 questions from the following list: (a) (b) (c) (d) failure of pressure control valve failure of expansion vessel failure of thermostat failure of high energy cut-out. The student will be given an outline of the symptoms only, in each case, and will be required to (a) make the correct diagnosis as to the fault and (b) state the appropriate remedial action. on the student attaining all the Performance Criteria

6 The following sections of the descriptor are offered as guidance. They are not mandatory. CONTENT/CONTEXT Corresponding to Outcomes 1-4: 1. Types of water heaters - low storage, non storage, instantaneous and multipoint heaters. Continuous flow, inlet and outlet controlled water heaters. Over and under sink, floor and wall mounted heaters. Water jacketed heaters, hot water provision by combination boilers. Fuel/power sources suitable for operating water heaters. Basic operation of water heaters, installation requirements and precautions for different types of water heaters. Temperature control, provision for water expansion in different types of water heaters. Sanitary appliances normally served by water heaters. Factors affecting selection of water heaters - selection of appropriate water heaters for given situations. Sketching and annotation of pipework, control service and drain valves necessary for installation of different types of water heaters. Water bye-law requirements and regulations relating to the installation of water heaters. 2. Direct and indirect units and packages; supply and distribution pipework; discharge pipework; typical pipe diameters; temperature control; three tier level of protection water flow control; prevention of contamination and waste; commissioning and testing; safety protection; legal requirements; terminal fittings. Methods of determining working pressures and acceptable flow rates on existing main supply pipework. 3. Functions of: filters/strainers; pressure reducing valves; pressure limiting valves; check valves; expansion relief valves; temperature relief valves; expansion vessels; high temperature cut-out devices; discharge pipework and thermostats. 4. Methods of tracing and rectifying faults in domestic mains-fed unvented hot water systems. Faults to include: expansion/pressure relief valve, temperature/pressure relief valve discharge, thermostat and high energy cut-out failure, expansion vessel failure, pressure reducing and limiting valve failure, choked strainer

7 SUGGESTED LEARNING AND TEACHING APPROACHES This module will be essentially classroom based with visits to project areas. Access to appropriate investigative layout is considered essential. The Outcomes could be covered by the use of: Prepared lecture notes and student worksheets. Full scale system/investigative layout. Samples of components, controls and safety devices. Manufacturers' catalogues and trade literature. Copyright SQA /02/98-7 -