Hi I fitted a honeywell y plan system some time back and all has been well...until tonight. I felt the DHW was too hot and turned the cylinder stat down and noticed later that there was no heating. The fused spur unit had blown its 3 amp fuse and did the same to the replacement. When I disconnected the cylider stat (honbeywell L641A) at the wiring centre i was able to get the heating to come on ( obviously with no control over the DHW) All components were new 5 months ago. Can you tell me how to check if the cylider stat has gone faulty or is there likely to be another cause for the fuses blowing. many thanks in advance.