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what one are you going to be installing
the ecomfort plus is an "A" rated boiler that does not have a zero governor, common faults for this type of boiler are the micro switch goes faulty this is quite a common fault on most Sime boilers they are aware of the issue and are trying to resolve it also the fan venturi only needs the slightest bit of dirt to stop the boiler operating
We recommend City Plumbing Supplies, BES, and Plumbing Superstore for all plumbing supplies.