I’ve checked everywhere and can’t find a leak only place is a little bit of water from the safety valve next to the boiler but it’s done that for years, I’m sure the tank feeds the hot water, from what I remembered the f and e tanks sits a little lower but I might be wrong, I have had a problem for a while with the f and e filling up with water and overflowing which I’m suspecting could be a hole in the coil so maybe it’s a faulty coil.??