Question: I purchased a used fireplace insert in good condition (Earth Stove, wood burning). My present fireplace has a metal heat form in it but no fans so is rather worthless for heating. Some clerks at local store have told me I need to add stovepipe up the chimney? There's a damper, plus the heat form's warm air vent pipes to get thru. They said I'd have to cut those out. That would pretty well demolish the heat form. Why can't I seal off the heat form with glass wool bat under shroud and next to the insert? Answer: I've run into some of these heat forms with welded pipes that cut across the damper area. These make it nearly impossible to place the normal 5 foot piece of flexible piping up through the damper. In these cases, I have installed a sheet metal block-off plate below the tubes and simply run the pipe from the stove an inch or two through this plate. The jobs I have done this way are working fine.