How to Reconnect a Radiator | Ask This Old House

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

Time: 1-2 hours
Cost: $50
Skill Level: Difficult

Tools List for Reconnecting a Radiator:

Shopping List:

Steps:
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.

Resources:
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.

About Ask This Old House TV:
From the makers of This Old House, America’s first and most trusted home improvement show, Ask This Old House answers the steady stream of home improvement questions asked by viewers across the United States. Covering topics from landscaping to electrical to HVAC and plumbing to painting and more. Ask This Old House features the experts from This Old House, including general contractor Tom Silva, plumbing and heating expert Richard Trethewey, landscape contractor Jenn Nawada, master carpenter Norm Abram, and host Kevin O’Connor. Ask This Old House helps you protect and preserve your greatest investment—your home.

Follow This Old House and Ask This Old House:

Watch the full episode:

How to Reconnect a Radiator

[Dametime]

I've been an industrial plumber for 11yrs now (2009 - ) and there's no greater feeling than finally connect a union fitting after a long day of laying pipe.

[michaelbaumgardner]

Fixing an old radiator is art that few know....good job Richard.!!!

[baritone]

That was VERY satisfying to watch a wedge and two levers get that thing in alignment with the valve!

[flyingozzy]

Guy: Hi Richard, I tried wedges and straps, but it doesn't work, I need help.
Richard: Let me show you the trick. What you actually need is a wedge and straps.

[sleepygrumpy]

Just excellent teaching from a guy who's seen it all -- great video

[jesusquiroz]

I don’t even know why I’m here... I don’t have a radiator.

[citrus]

Sometimes two heads and two sets of hands is all you need. Thanks for the info.

[jerseydevil]

I can’t even imagine the amount of stress that the two pipes are getting

[johnroberts]

Hi TOH, I like too watch Rich Tretheway show us new products in plumbing & how to fix & repair things involved with plumbing ! 👍😃🚿🚽🛀

[neilh]

Hemp and candle wick work similar for thread sealant. They expand and seal if they get wet.
Originally here it looks like it went into a 90 with a LR nipple. Always difficult adding the Dahl valve.

[Freddyfrm]

Maaannn he had to do it with his left hand. Thanks for helping the plumber out.

[alec]

This feels like an episode from 2003. Usually the homeowner just sits and watches in recent seasons.

[tedcarl]

Sheithowdy, learned something new on the thread filler.

[jameskappel]

Does the system ever need to be flushed (something like a vehicle radiator) because of hard water build-up or contaminants? Does an additive get added to prevent rust/corrosion, etc...? Thank you.

[matthewmillard]

Ive seen some people bleeding the radiators through a screw on the top of the radiator with a radiator key..it was explained that this method is to get air out of the radiator. Is this method needed with steam heat radiators that have side vents? Ty.. Matthew

[markzamiechowski]

If anyone didn't have wicking just use horse hair and grease we do this in Poland and it works all the time because Teflon tape is just not economical to use

[BrewersArcade]

Very informative. I would totally screw this up

[nnamerz]

How is that strap attached to that 2x4? It was difficult to tell from the angle they filmed.

[robstephens]

Should have cut about 1/2 in. extra threads on existing pipe or replaced it with one about 1/2 in. shorter. It would then go together without all of the lifting and prying, and there would be less stress on the pipe and radiator.

[joeyporto]

Whatever happened to radiator heaters?