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How to Convert Radiators into Multi-Zone Heating

Upgrade an old radiator heating system with This Old House plumbing and heating expert Richard Trethewey.

Steps for Converting Radiators to Multi-Zone Heating

  1. Apply pipe dope to threads of the riser pipe and thread it into the radiator pipe. Tighten the connection with pipe wrenches.
  2. Trim the end of PEX tubing with a cutter, then use a calibration tool to ensure cut end is clean and perfectly round.
  3. Slide the compression sleeve onto the end of the tubing, then push the tubing onto the fitting at bottom of the supply riser.
  4. Use a compression tool to crimp the compression sleeve onto the fitting, forming a watertight joint.
  5. Attach another length of PEX tubing to the opposite end of the radiator to serve as the return tubing. Run two lengths of tubing—one supply, one return—from each radiator.
  6. Mount the manifolds to the wall near the hot water tank.
  7. Connect the tubing ends (supply and return) to the manifolds.
  8. Run piping from the manifolds to the hot-water tank.