Really weird probkem with insert moving !

[Sidgey]

Hi, can anybody tell me why this is happening. I have an insert style woodburner connected to a stainless steel double walled insulated flue. It was Installed about 9 years ago. It is mounted on a concrete slab which itself is mounted on firebricks. The whole is set inside a false chimney breast with the appropriate air vents etc. The thing is it has started moving when in use it is very gradual but over the past 3 months it has moved about 20mm sideways. At first I thought that the cement base or one of the fire bricks might have crumble or cracked but I was able to check this by removing one of the grills covering an air intake at the bottom of the false chimney breast and everything is fine ? Theoretically it should be impossible for the insert to move as it is connected to the flue which is held rigidly in place.
Just as weird is the fact that to move it back I have to use a length of 3 x 2 and a lump hammer and hit it really hard over and over to get it to move back. Oh, and it makes a loud clicking noise every so often when in use.
Anyone any idea what is going on? Thanks

 

[Mech e]

Going out on a limb here, but could thermal expansion and contraction of the stove body cause it to walk???

 

[Woody Stover]

Or could expansion of the chimney be pushing it? Not likely to move it that far, I wouldn't think..

 

[Grizzerbear]

Or could expansion of the chimney be pushing it? Not likely to move it that far, I wouldn't think..

This is kinda what i thought. Maybe sthe insert wansnt exactly centered to the attached chimney and thermal expansion is correcting it. Just a guess lol.

 

[blacktail]

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[bholler]

Stoves move all the time you put force on it every time you load wood or shut the door.