How to remove stuck threaded pipes from an old boiler without breaking it
Old threaded boiler pipes often seize up completely, leaving DIYers afraid to apply enough force with a large wrench for fear of cracking the fragile cast iron bowl. This makes it nearly impossible to disconnect old plumbing or remove stubborn solvent-welded fittings without risking major damage to the heating system.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Calling a professional plumberDid this help you?
- 2Cutting the risers and nipples instead of unthreading everythingDid this help you?
- 3Using two wrenches to back up instead of just oneDid this help you?
- 4Delaying the work until after the heating seasonDid this help you?
- 5Acquiring more toolsDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“PVC pipe won’t come out on its own, ( I believe it is rightfully solvent welded) so do I need to take connector out? I’ve tried but it won’t budge.”source ↗
“I have a big 24” wrench but I’m afraid to apply a lot of pressure. I don’t want to crack the boiler’s bowl.”source ↗
Where this came up
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