Ideal Heat Exchanger Sub Assembly F240-F480 174402

The Ideal 174402 is a heat exchanger sub assembly manufactured by Ideal for its commercial boiler range. It sits in the combustion path and transfers heat from the burner gases into the appliance water circuit, so it is central to how the boiler delivers its rated output. The assembly is listed against the F240 to F480 commercial models and the wider Imax Xtra family.

• Falling flow and return temperatures, or the boiler failing to reach its setpoint despite the burner running.
• Kettling, banging or rumbling noises from the heat exchanger as scale or sludge restricts the waterways.
• Water weeping from the exchanger body, its seals or its connection points.
• Repeated overheat lockouts or high-limit trips on the appliance.
• Combustion readings drifting outside the expected range, or visible sooting and discolouration around the exchanger.

• Check the appliance data plate and serial number against the compatibility list to confirm the model and rating.
• Confirm the existing part number on the appliance matches 174402, and note the alternative number 1782156 when cross-referencing.
• Inspect the seals, gaskets and connection washers on the exchanger joint and order replacements where they are being disturbed.
• This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.