I arrived home last night to a cold flat. Which was odd, because the super-timer-thermostat (official name) is remote-controlled, battery-powered and rather wonderful... power cuts are not a reason for it to mess up. And I'm not sure there had been a power cut anyway.
So I opened the wardrobe (for this is where the boiler is - don't ask). A red light was flashing. This is not usually a good sign.
The display was also blinking: "0.6".
Now, I happen to know that, when the boiler is idle, the display reports the pressure in the heating circuit. I know this because I am boring and read the manual when the boiler (Glow Worm 30CXi) was installed earlier this year.
Normally, it reads about 1.5 - and the instructions on the front say it should be at least 1.0 in normal operation.
I suspected a leak but could see nothing obvious (in other words, the floor wasn't wet and there was nothing oozing out of any of the radiator valves).
So, I used the blue plastic knob to top up the heating circuit and the pressure rapidly rose to 1.1.
The boiler worked for the rest of the night and the flat was warm. At bed time, the pressure had dropped to 0.9, which I thought odd. The water in the heating circuit was now warm, so I would have expected the pressure to be higher than 1.1, since the 1.1 reading was taken when cold.
I didn't top it up but fell asleep with a sense of foreboding.
Sure enough, I woke up feeling cold this morning. I jumped out of bed (something I never do unless I have an important problem to solve!) and checked the boiler.
Back to 0.6 and a flashing red light. Arghhhh.
There must be a leak. But where? Under the bathroom tiles? Under the new stone floor in the kitchen? I hope not. Under the laminate floor? None would be particularly desirable.
Regardless, I topped it up again and called the plumber at 9. He shared my suspicion of a leak and is coming out later.
In the meantime, I pulled some boxes out of the airing cupboard and noticed that carpet was damp.
The leak is in the airing cupboard.
I'm not sure where in the airing cupboard. But in there somewhere. So it's not as bad as it could have been.