gas reading anomaly

Did the heating kick in overnight?

I noticed mine do that one day a month or so ago. When I checked the boiler I found that the mechanical timer had broken (sometime over the summer) and had stopped during an ‘On’ period.

That meant it was stuck at “On’ for 24 hours a day, and so when the temperature dropped at night the boiler fired up.
(I got a new timer).

Another possibility is if you have had a power cut, or the power has been off for some other reason*, and the timer was stopped so now shows the wrong time, so could come on during the night.

*I recently also had EICR testing done which means turning the power on and off several times, so had to reset my new timer after that.

Check your boiler timer to make sure it is working and is set correctly.

My gas boiler for heating is, in reality, on every day from 6.30 am to 11pm. In addition to the timer, we have the system thermostat and the individual room thermostatic radiator valves that control when the heating actually does fire up. It has, in the last week come on three times at 6.30 am, for a short period. 

Thank you all for replying.  Just had a new boiler installed.  Have not had heating on yet and won’t be putting it on a timer, only as and when I want it on.  The heating temp is below what room temp is so won’t come on.   Have only been using a boost for hot water during the morning which is registering on my usage that is when I notice that 1.5 hours of gas had shown up at 5am.  This is the first time this has happened as I check the usage daily.

Could you tell us what make/model your new boiler is?

You say you used a heating boost, which says that it isn't a combi boiler but that you have a hot water tank.

If we know just what it is then we could look up the manual to see the controls and how it works. Which should avoid asking lots of questions.

It's not clear just what you mean by:

“ The heating temp is below what room temp is so won’t come on. “

Which “heating temp” ? The thermostat setting? or the radiator flow setting?

TBH we often get questions about strange usage over night (both electricity and gas) and it almost always turns out to be a setting error, a forgotten detting, or a forgotten heater that is on a thermodtstic control. (Like an oil filled electric patio heater).

If  it was simply a cold night where you are, and the room temp dropped overnight, then from what youe have described the heating could have come on.

Another alternative as you appear to have a water tank would be if the tank cooled down overnight and the tank thermostat signaled the boiler to heat it up again.