Hot house blues

My house was lovely and warm when I came home last night - which was a little worrying, as I hadn't put the heating on.  Maybe I'd actually had it on all summer, but it hasn't been cold enough for the thermostat to kick in? {Or maybe the heating had been on, and I'd only thought it was a nice summer.}  No, the dial on the control box was definitely in the 'off' position... but the display was flashing madly, and telling me the time was 12.15, which it wasn't.  Perhaps we'd had a power cut?  "Perhaps it just needs new batteries," my Beloved suggested.

What did he mean, batteries?  Surely the control box is connected to the electricity, otherwise how does it turn the boiler on?  Oh yeah, wi-fi.  And, on reflection, I did remember being told when they installed the boiler that I could have the control box anywhere.  But in my defence, it is next to a light switch, and I wasn't there when they set it up, so for all I knew they could have connected it to the mains and just replastered the wall very well.

Anyway, I decided to check the instruction booklet.  Yes, I do keep instruction booklets.  I selected the appropriate one, and discovered that the unit did need new batteries.   But not just any old batteries.  "Only good quality alkaline batteries should be used",  it informed me in bold type.  "DO NOT use rechargeable batteries".  Why ever not?  All I have are rechargeable batteries, and they work perfectly well in everything else.  I have them in my kitchen clock, and that's got physical moving parts - surely clock hands take more effort to move than sending an electrical impulse to a switch?  I mean, there's air resistance trying to stop the clock hands moving, to say nothing of their weight.

I should perhaps admit that I only have CSE Grade 2 in physics, and I only have that because we had to do a science.  Chemistry seemed interesting, but I was too scared to light the Bunsen-burner.  I couldn't face the idea of cutting up frogs and eyeballs, so biology was out, and domestic science didn't count. {But since that also involved lighting flames and cutting up dead animals, I couldn't do that either.}

Reading on in the instruction booklet, I discovered that the boiler was now intending to operate continuously until it got new batteries of acceptable quality.  How ridiculous is that!  What if I'd been on holiday?  My smoke detector beeps when the battery is running out, and then just stops working.  I have a combi-boiler, which spends most of its time not doing anything, so why is the fail-safe mode to suddenly start doing something it wasn't doing before?  And without even a beep to warn you!

Anyway, I bought some batteries today, and prepared myself to change them within the 30 seconds allowed before all my settings were lost.  Despite managing to drop one of the new batteries and the unit cover down the back of the bookcase, I thought I'd managed it in time.... but the display is still flashing.