I'm too forgetful to remember that if it's hot, I have wired the fans to a switch, or if it's cold I need to turn the switch off. A cheap NTC from a gas boiler should auto regulate it.
(NTC is the common slang for Negative Temperature Coefficient, meaning that contrarily to normal laws of physics, the device reduces its resistance as the temperature rises)
PART NUMBER;5114725. Baxi PLATINUM COMBI HE 24. Baxi PLATINUM COMBI HE 28. Baxi PLATINUM COMBI HE 30. Baxi SOLO HE 15. Baxi SOLO HE A 15. Baxi SOLO HE 18. Baxi DUOTEC HE 24.
www.ebay.co.uk