Ideal 173799 Printed Circuit Board 25E

The Ideal 173799 is a printed circuit board used in Ideal domestic gas boilers, listed by the manufacturer under the PCB and control box part group. It carries the 25E designation and sits at the centre of the appliance's electrical control system, handling burner sequencing, ignition timing, temperature regulation and the safety interlocks that shut the boiler down when a fault is detected. It is a direct replacement board for the units listed in the compatibility table below.

• The boiler locks out repeatedly and will not reset, or resets only briefly before failing again.
• No response from the controls: the boiler does not attempt to fire when there is a call for heat or hot water.
• The display or indicator LEDs are dead, flickering or showing an error code that does not clear.
• The fan, pump or gas valve runs erratically, or the boiler cycles on and off without reaching temperature.
• Visible damage on the board itself, such as scorching, a blown track or a swollen capacitor.

• Confirm the model and GC number of the appliance against the compatibility list before ordering, as board variants are not interchangeable across the range.
• Check that the part number printed on the existing board matches 173799, and note any alternative number shown on the old component.
• Isolate the electrical supply and follow the manufacturer's wiring diagram when fitting; boards are polarity and connector-position sensitive.