I'm puzzled.
I have an oil-fired boiler (a Danesmoor 15 /19) - as I've always understood these things, once the thermostat in the hall senses that the temperature has reached the preset value it will turn off the heating.
If the heating goes off (due to the thermostat switching it off) it should then be possible to make the heating come back on again by turning up the thermostat, correct?
My boiler isn't doing this - wasn't doing it before I had the (old, slightly faulty) thermostat replaced and the new thermostat isn't doing it either.
It will happily reach the thermostat's preset temperature with the radiators getting nice and hot, BUT it then switches off and even though the thermometer in the hall indicates that the temp has gone a few degress BELOW the thermostat's cut-in point, AND the radiators are cooling off markedly, the heating stays resolutely off until it gets really cold. And it's not the thermometer that's 'off' either, I can tell it's getting colder.
The thermostat isn't wrongly placed.
I SHOULD, as I understand it, be able to turn up the thermostat to, say, 30 (it's usually at about 22) and the radiators should start to heat up again. They aren't.
And yes, the boiler IS switched on. :)