New wood burner question

[Streaky17]

We had a wood burner installed a few months ago but only now using it more often. We followed instructions by having 2 low fires before using it fully.
I've just noticed that where the flue (?) connects to burner the cement (I think) is cracking and fallen away. Photos attached.
I will contact the shop/installer on Monday but I want to be prepared for what they might say.
Is this normal?
Did they use the wrong material?
How long should it last?

Thanks in advance

I'm sure there should be no gaps. Have you also a carbon monoxide monito, nearby? The installer should have been HETAS registered and have put a monitor in the same room.
I'd insist they rectify the cement.

Fire cement inevitably cracks when the flue heats up and expands then cools down again.

We just reseal one a year with fire concrete (ours cracks where it goes into the register plate).

I'm looking into using a high temperature flexible sealant which I think may save me a job each year.

I'd be interested to hear what your installer says.

Thanks JT05 Yep. All done by shop. CO monitor in corner and we have the hetas certificate for the installation.
I'm concerned if they redo it will reoccur unless they or we do something different.

Hey heymacwey I just looked up slight crack all the way round the register plate but all the cement still there.

In just checked our wood burner (properly installed four or five years ago, reputable local firm etc etc) and lo, the cement has cracked and is largely gone. That means that it wasn't there last year either, as we've only lit it once this year. Not a murmur from the CO monitor, ever.

If gases were leaking, I would expect to be able to see and smell smoke as well, and we never do.

That's normal, the fire cement does crack. I would ask them to seal it with their silicone which will not crack