Boiler is a Potterton Kingfisher 100/75K (in/out, can't remember model) conventional vented gas system. Fully pumped CH & DHW. Honeywell controls. Regularly maintained. Rather aged but works very well. This afternoon at about 16.20 I went into the boiler room to hang up my overalls. A very mild afternoon. Very hot in here thinks I. Check temp gauges on flow & return. Flow is showing about 72 deg C. Return about 48. Temp gauges are clip ons and perhaps not highly reliable. Normally the flow does not exceed 60 and return is about 4-6 deg behind. Shut the system down from programmer. Felt the local rads and they are far hotter than usual. All rads bar one have trv's. Checked the room stat which controls the whole CH system, this is set to about 18deg. Gave it a twiddle and could hear it click on/off. Reset to
18deg. Checked the boiler stat which was set to about 3 (max 5). Gave twiddle and could hear this clicking on/off. Reset boiler stat to 2 and restarted system from programmer. Pump started and after a few minutes the boiler kicked in. Kept an eye on it for a while and it appears to be working quite normally.
56/50 temps shown on gauges but at a lower boiler stat setting than usual. I wonder if the boiler stat is on the way out? For what it's worth this happened during the worst squall that I have ever known in this country, and I have been here for 60 years.. Accompanied by lightning & thunder. I imagine this is not connected. Any thoughts please? Nick.