My folks lived in a 100-year-old house, complete with cast iron radiators. Charlie Bethel, a Burlington, Vt., plumber passes along these tips for adding panel radiation to an existing hot water heating system: Size the radiator to the calculated heat loss for the space; check the BTU output of the boiler to be certain that the new heated space won't exceed the boiler's capacity; and install a monoflow valve on the return side of the heat loop, which will direct return-side hot water back to the boiler.But the secret to panel radiators is PEX-AL-PEX, a tubing sandwich with inner and outer plastic casings surrounding a thin-wall aluminum hose. The compression fittings are tightened with adjustable wrenches; the crimp-on fittings require specialty tools.With PEX-AL-PEX tubing, an installer can snake through obstacle-ridden areas where rigid tubing might require additional demolition or contortions.
