Why is my boiler doing this?

[ISeeTrees]

I have a combi boiler (I think? It does gas central heating and hot water). I have the heating switched off, and manually turn it on when I need to.
I've been WFH and, like many, a bit obsessed with energy usage. I've noticed that throughout the day, for about 2 minutes, the boiler fires up as if I've switched on the heating or hot tap.
Why would it keep doing this? I'm going to listen out for it tomorrow and nip outside to see what it's doing on the gas meter.

Combis maintain a heat core to enable hot water to run quickly, and fire up periodically to enable this.

I have always had a combi and never noticed that. Do you have a hot tap dripping somewhere?

I've had several combi boilers and non have done that.

What make is it, and how old?

It might be heating up hot water ready for use.
Have you got an eco mode for hot water? Turn it on and it will stop doing this (if that's what it's doing).

Some have a 'comfort' mode that keeps the water in the boiler warm.

Our has a periodic cleaning cycle for the flue

Money also has an eco mode which does this, which means hot water takes longer to run as the core isn't as hot.

money mine

Ours used to do this under what it called a "pre-heat" function that would pre-heater water just in case we then turned on a hot tap, thereby meaning we got hot water faster. I think rather than "pre-heat" being a positive factor, they now give the positive spin to the opposite setting as 'eco mode' (i.e. pre-heat off). Either way, you can switch it off, we did at the start of the summer on our knackered-and-due-for-replacement boiler.

www.boilerguide.co.uk/articles/boiler-fires-turns-off , one of many articles, Google "why does my combi boiler fire up randomly" or similar.

Thanks all. No hot tap dripping anywhere. The preheat thing/keeping core warm would make sense- the hot water does take a bit of time to come through though so it's not working very well!
I've had this boiler in for about 10 years I think, it's a Vaillant.
I'll check for an eco mode or similar, though the interface is pretty basic.

My boiler is a vaillant and has an eco mode that's activated by turning the hot water dial all the way down and waiting until it does a little click, then you turn it back up to the temperature you want the water at

Ahh @CountdownCat I think you've solved it. I've only noticed it in the last couple of weeks- I thought it was just hyper-vigilance but when I think about it, it coincides with when I adjusted the tap temperature on the boiler because my bath wasn't running hot enough! Thanks, I hadn't made the connection!