"Bought this to replace like for like programmer. Previous one hade been installed for about seven years. The ideal heating control for a combi boiler. Has the facility for seven day planning with 3 on- offs in any 24 hour period."
"The "si" is the Service Interval timer. This is very annoying, as it is set to stop the boiler working properly after about a year, to force you to have it serviced. It is usually fitted in tenanted homes where the landlord does not trust the tenant.
I'm not surprised the price has been reduced. It is a great nuisance.
Unless you are a landlord, don't buy it. You will not be able to reset it yourself."