Please contact your Gas Safe engineer to discuss the suitabilty and requirement of the ancillaries for your instalation.
Mechanical Sequencing Valve
Electrical Sequencing (Maximum 2 Heaters)
Electronic Sequencing Systems (Internal Water Heaters (Up to 25 heaters))
Electronic Sequencing Systems (External Water Heaters (up to 25 heaters))
Digital Controllers (not for 16i)