Question: I just purchased a house with a fireplace. At the bottom of the fireplace is grating filled with water and connected to pipes with a circulator and expansion tank go to the blower on the central air condition unit to distribute the heat through the ducts. The enclosure is metal within the fireplace. The house was built around 1973. There is no obvious identification of the manufacturer that I can locate. This would help me to repair the damage caused by a chimney sweep installing a damper on the chimney who drilled through the sheet metal and had water shooting out. I don't know if the metal enclosure is filled with water or if he hit a pipe. My question is : how to identify the manufacturer to understand the design and obtain replacement parts if possible to repair this. An explanation of the design from that timeframe would be appreciated too. Answer: You can be sure that the manufacturer is no longer around. To my knowledge, there is no current maker of hydronic grates of the type you mentioned. There was a company named HydroHearth that built such things over 20 years ago. You should have a hydronic expert (plumbing/heating) check this out to make sure it is operable. Make CERTAIN that a pressure relief valve is installed and that it is functioning. Also, make certain that the controls and circulator are functioning as designed. Failure to do this could result in a lot of problems, including superheated steam explosion... As far as the hole, my guess is that he hit a pipe, as sheet metal would rarely be used to encase pressurized and heated water.