Ok, instructions say to place a bead of sealant under the anchor plate for the chimney. The top of the unit has a sheet metal top (probably 25ga) with the chimney pipe sticking out about 1/4 inch. I suppose the anchor plate extends down into the chimney pipe and then the flange of the anchor plate screws onto the sheet metal top. What type of sealant woulkd I need, the instructions offer no suggestions and there is no reference to temp requirements.