Inhibitor & Water Treatment Flashcards

What is the primary source of oxygen in a vented central heating system?

Answer: The open feed and expansion cistern, through which air is constantly in contact with the system water

In a vented (open) system, the feed and expansion cistern exposes the system water to the atmosphere, providing a continuous source of dissolved oxygen that drives ongoing corrosion unless inhibitor is maintained.

Why do sealed systems generally experience less corrosion than vented systems over time?

Answer: Once dissolved oxygen is consumed in initial corrosion, no more oxygen enters, so the corrosion rate drops — provided inhibitor is present

In a sealed system, once the initial oxygen dissolved in the fill water is consumed, no more oxygen enters; with inhibitor present, the corrosion rate falls significantly compared to an open system with its continuous oxygen supply.

What is the significance of pH in central heating system water?

Answer: Maintaining a slightly alkaline pH (7–8.5) minimises corrosion of both ferrous and non-ferrous metals in the system

The pH of system water affects corrosion rates; a slightly alkaline pH 7–8.5 is protective for both steel and aluminium components. Very high pH damages aluminium; acidic conditions attack ferrous metals.

What is a 'no flush' scenario and why is it poor practice?

Answer: Installing a new boiler on an old system without flushing, exposing the new boiler to existing sludge and debris

Connecting a new boiler to an unflushed old system means sludge and debris immediately circulate through the new heat exchanger, causing rapid degradation, frequent service calls and early failure — typically invalidating the warranty.

What is the role of the ADEY MagnaCleanse or similar flushing system in water treatment?

Answer: To rapidly flush sludge and debris from the system using a high-flow magnetic filtration unit connected to the system pipework

Systems like ADEY MagnaCleanse use a high-flow magnetic filtration unit connected across the system to rapidly capture magnetite and debris, providing a targeted flush of heavily contaminated systems.

After water treatment, what should be recorded on the boiler service record?

Answer: The inhibitor product used, dose, system volume, date of treatment, inhibitor test result, and any additional treatments applied

Complete water treatment records should be entered on the boiler service record at every visit: inhibitor brand, dose, test result, date and any additional measures. This creates an audit trail and supports warranty claims.