Old Heatilator Hearth Glue Smell

[KyleTile]

Hi All

I would appreciate some insight into an issue we've noticed after purchasing our home about a year ago.

The house was built in early 1960s with a fire place added on sometime (I think not too long maybe the 70's) after. There is an electric powered heatilator with air intake just above the hearth and vents in the brick just under the mantle. We have had it professionally cleaned when we purchased the house and maybe made 2 fires since so it is very clean.

We noticed a smell like some sort of fumes almost like a glue or adhesive coming off the hearth, you have to go close but it is there. When you lay on the floor in the room you can also catch the smell.

I noticed a hole on either side of the hearth, looks like a gap intentionally left there and there was some air coming out. I talked to my chimney guy and he said everything is normal and just suggested just plugging it with a sponge to see if that helped block the odor. You can see from the pictures what I'm talking about, I put a yellow sponge in the gap.

Any tips on how to eliminate the smell? it doesn't smell like the fireplace so it seems odd. This is a over a crawl space and the chimney guy went down there and said everything looked normal. The crawl space is maybe a little musty but not like this type of smell. It seems like the smell is inside the hearth, not sure if anyone knows what could be in there?

Thanks