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How to Reconnect a Radiator

A homeowner’s radiator sprung away from the pipe when he tried to replace the valve, so Ask This Old House plumbing and HVAC expert Richard Trethewey heads to his house to help him reconnect it

1. Start by shutting off the boiler and the cold water feed to the boiler.
2. Drain the system using a hose and vent each radiator in the house.
3. Remove the temporary caps using the pipe wrenches. When using the wrench, be sure that it touches the pipe in three places so it does not damage the pipe.
4. Disconnect the spud from the radiator valve.
5. Apply the pipe dope to the threads of the spud and seal it with the single strand wicking.
6. Using the spud wrench, carefully tighten the spud in position. Be sure the threads correctly catch to prevent damage to the spud.
7. Apply the pipe dope and wicking to the pipe coming up through the floor.
8. Thread the other half of the radiator valve onto the pipe, again being cautious of cross threading.
9. Tighten the radiator valve using the pipe wrenches. Once the valve is in the direction of the radiator, it can be reconnected.
10. Wrap the ratchet straps around the legs of the radiator and put a 2x4 or another piece of scrap wood into the strap. Using the 2x4 as a lever, carefully pull the radiator into position with the valve. It might help to wedge shims on the other side of the radiator to hold it in place. You can use multiple levers if you need to adjust the height as well.
11. Once the radiator has been moved so it’s perfectly aligned with the valve, connect the valve to the spud using the nut that connects the two.
12. Once the connection has been made, tighten it with a wrench.
13. With all the work done, turn the cold water feed and the boiler back on and vent all the radiators again.

All the tools Richard used to reconnect the radiator, including wrenches, pipe dope, wicking, and the radiator valve, can all be found at home centers and plumbing supply houses.