Hiu Servicing - hiursm

Servicing

Servicing a Heat Interface Unit (HIU) is essential to maintain efficiency, safety, and performance over time. An HIU service typically involves a thorough inspection, cleaning, and testing of both the domestic hot water (DHW) and space heating components.

Here’s a breakdown of what an HIU service usually includes:

Visual Inspection: Check for leaks, corrosion, and signs of wear. Inspect pipework, valves, and insulation. Confirm correct labelling and accessibility.
Clean Filters & Strainers Remove and clean primary and secondary strainers. Check for debris or sludge buildup. Replace filters if necessary.
Check & Test Expansion Vessel: Measure pre-charge pressure (usually 1 bar when the system is cold). Re-pressurize or replace if faulty.
Check Pressure & Temperature: Confirm primary and secondary system pressures. Verify correct operating temperatures for DHW and heating Will adjust if necessary.
Flow Rate & Heat Exchanger Performance Test DHW and heating flow rates. Check plate heat exchanger for scaling or fouling. Clean or descale if needed (especially in hard water areas).
Test Safety Devices Check pressure relief valves (PRVs) for operation and signs of discharge. Test any thermostatic mixing valves (TMVs).
Electrical & Controls Check: Test sensors, actuators, and thermostats. Inspect electrical connections for wear or damage. Verify correct operation of control systems or BMS interface.
Functional Testing: Run the HIU in both heating and DHW modes. Check response times and output stability. Ensure system shuts down properly when demand ends.
Record Keeping Note down all test results, observations, and any adjustments made. Recommend any repairs or parts replacements. Provide a service certificate.

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