8 Hot Water Systems: Testing & Decommissioning

• Key requirements for testing and decommissioning domestic hot water systems

Requirements of Testing, Commissioning and Decommissioning

• Testing procedures for ridged pipework and plastic pipework are essential.
• Flushing and disinfecting ensures water is wholesome.
• Commissioning and decommissioning procedures, both temporary and permanent are required.

Soundness Testing

• Before testing, visually inspect all joints to make sure they are correctly assembled.
• Look for open ends, soldered joints, tight compression joints and secure clips.
• Soundness tests for rigid pipes and plastic pipes differ.

Soundness Testing: Procedure

• Visual inspection.
• Setting up equipment.
• Testing period.
• Final check.
• Complete documentation.

Soundness Testing: Rigid Pipe (Copper and Steel)

• Slowly fill the system with water.
• Walk around the system checking for leaks.
• Leave the system for 30 minutes for temperature stabilization.
• Attach the hydraulic test bucket.
• Pump the system up to 1.5 times the working pressure; a system working at 3 bar should be tested at 4.5 bar.
• Leave for one hour.
• Check for any pressure drop; none is allowed.
• Rectify and re-test if necessary.

Soundness Testing: Plastic Pipe (Polybutylene)

• Slowly fill the system with water.
• Walk around the system and check for leaks.
• Pump system to 1 bar; check for loss of pressure after 45 minutes.
• Increase pressure to 1.5 times the working pressure for 15 minutes.
• Check for pressure loss.
• Reduce pressure to one-third for a further 45 minutes, then check for pressure loss.
• Main point is to avoid damaging the plastic pipe or O rings.

Flushing and Disinfecting

• New systems or pipework sections must be flushed to remove debris.
• Pipes must be prepared to carry safe, wholesome water.
• Refill the system with water, then drain it from the lowest point.
• Re-fill the system.
• Open the kitchen tap and allow water to run until it is clear of debris or discoloration.
• Repeat for all other outlets in the property.
• Add disinfectant, either sodium hypochlorite solution or chlorine, to the system for 1 hour.
• Follow standard BS EN 806.

Flushing and Disinfecting Continued

• Chlorine levels must be tested at each outlet as per BS EN 806.
• Drain the system.
• Flush the system through from each outlet until no chlorine is present.

Commissioning

• Flow rate pressure must be measured using appropriate tools, such as a weir cup or pressure gauge.
• Flush to remove dirt and debris as per BS EN 806.
• Open all draw-off points, making sure they open and shut off.
• Open and close all valves to ensure operation, and ensure valves are labeled.
• Ensure correct thermostat and blending valve temperature settings and inform the customer.
• Ensure correct temperature at draw-off points and record.
• Check the overall operation of the system, then complete documentation.
• The customer should be shown all settings and valves; must also receive manufacturer's instructions; benchmark and warranty certificates.

Decommissioning

• Decommissioning a hot water system for maintenance and component replacement is a critical task.
• Key steps include informing the customer, identifying components and safely isolating the heat source.
• A warning notice must be placed on the heat source and fuses removed.
• The system must be drained to a safe location with open ends capped and no dead legs left.

Temporary Decommissioning

• Temporary decommissioning occurs when a component or appliance needs replacement.
• Customer must be informed.
• The system must be safely isolated and labeled.
• A hose pipe must be connected to a suitable drain point and discharged to a below-ground drain.
• The part is then replaced, and the system is refilled and tested.
• Common items requiring temporary decommissioning include hot water cylinders, cold water storage cisterns, boilers, showers, valves, appliances, and terminal fittings.

Permanent Decommissioning

• Permanent decommissioning occurs when an old system is replaced or a building is prepared for demolition.
• Customer must be informed.
• The system must be safely isolated and labeled.
• A hose pipe must be connected to a suitable drain point and discharged to a below-ground drain.