Steps for Converting Radiators to Multi-Zone Heating
- Apply pipe dope to threads of the riser pipe and thread it into the radiator pipe. Tighten the connection with pipe wrenches.
- Trim the end of PEX tubing with a cutter, then use a calibration tool to ensure cut end is clean and perfectly round.
- Slide the compression sleeve onto the end of the tubing, then push the tubing onto the fitting at bottom of the supply riser.
- Use a compression tool to crimp the compression sleeve onto the fitting, forming a watertight joint.
- 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.
- Mount the manifolds to the wall near the hot water tank.
- Connect the tubing ends (supply and return) to the manifolds.
- Run piping from the manifolds to the hot-water tank.
Why Multi-Zone Matters: In a traditional radiator setup, when the thermostat calls for heat, the pump sends water through all the radiators at once — and the water naturally takes the path of least resistance, favoring larger pipes and starving smaller ones. By converting to a manifold-based multi-zone system, each radiator gets its own dedicated supply and return lines, ensuring every room receives the right amount of heat regardless of pipe size or distance from the boiler.
Pro Tip: Richard Trethewey, This Old House plumbing and heating expert, emphasizes the importance of serviceability when installing any new heating components: “Proper installation requires, or invites, having shutoff valves on both sides of any circulator pump. You wouldn’t believe the number of times you walk into a beautiful heating system and there’s no way you can service that but draining the whole heating system.”
