Hi all, Been noticing that all of my google searches about wood stoves leads me here, so I figured this was the best place to start! Here is my story. I just got a 90 Lopi Revere that I am about to cram into an existing ZC. The damper handle of the ZC said "Heatilator" on it, so I assume that's the brand. Not sure of the model but there are blowers in the brick face that my chimney sweep told me were part of the unit. My house was built in '58 and I cannot imaging that this prefab was installed after the fact, so it must be about that old. The chimney sweep inspected it and told me NOT to burn in the ZC unless I installed an insert WITH a SS liner. The chimney has clay liner already but the problem, he said, was that (since previous owners never installed a cap) water damage has ruined the ZC and where it meets the actual chimney is no longer sealed/safe. So I had planned to install a wood burner insert anyway, just wasn't expecting to need the liner. No biggie, got a UL listed SS kit with insulation and just need to do some cutting to get it to fit. So tonight as I was cleaning out the fireplace and cutting out the damper I noticed there are some gaps in places. That is what I need help with...do these gaps matter since the firebox and exhaust will be sealed off from the ZC? Said gaps are around the perimeter of where the insert should butt up against the brick face. Gaps are maybe half and inch or so, I can see insulation through them. I would ASSUME the insulation is fireproof, as it is installed within a fireplace unit, but we all know where ASSumptions can get us ;-) Should I be concerned with any gaps like this? Must I fire caulk/cement them? Any other general suggestions based on what I am doing here? Thanks for the help guys, much appreciated.