Welcome to the forum. Although you can post in any forum, the USA forum is here in case of local regs or laws

Install the app
How to install the app on iOS

Follow along with the video below to see how to install our site as a web app on your home screen.

Note: This feature may not be available in some browsers.

Apr 8, 2022
141
20
18
UK
Member Type
DIY or Homeowner
Hi,

I had a new radiator fitted around a month back and I've noticed the joints which are sealed with Hemp (or modern equivalent / Boss White appear to be slightly discoloured / rusty. This might simply be a little seepage before the joint sealed etc as there is not weeping from the joint that I can see / feel. Is this normal / expected? Might seem paranoid, but I'd rather get something resolved now rather than have a rusty radiator several months down the line.

I'm surprised Hemp (or modern equivalent) / Boss White is used these days but many folks seem to swear by it.

Thanks...
 

Attachments

  • IMG_8706.thumb.jpg.77d431dec76f4fd463b85b2c35f1b8ed.jpg
    IMG_8706.thumb.jpg.77d431dec76f4fd463b85b2c35f1b8ed.jpg
    57.8 KB · Views: 57
  • IMG_8707.thumb.jpg.78b13f7510be99906facc35412705c5f.jpg
    IMG_8707.thumb.jpg.78b13f7510be99906facc35412705c5f.jpg
    31.9 KB · Views: 49
I would keep an eye on it for the next month even if it’s putting a kitchen towel below the joints
I fully intend to but thanks for calling out. Is it common for this to happen prior to a seal? Like some expansion / curing takes place? I'd personally have thought PTFE would have been used opposed to 55 and boss white.
 
I'd personally have thought PTFE would have been used opposed to 55 and boss white.
It occurs to me that perhaps the radiator had slightly oversized threads and/or the connectors were undersized and ptfe wasn't sealing. (If you use a good quality brand of radiator, e.g. Stelrad, the chances of this sort of problem are very low IME.)

Another possibility is that the installer had to dismantle the joints for some reason and transferred some rust from the threads onto the hemp in the process.
 
  • Like
Reactions: techweb
It occurs to me that perhaps the radiator had slightly oversized threads and/or the connectors were undersized and ptfe wasn't sealing. (If you use a good quality brand of radiator, e.g. Stelrad, the chances of this sort of problem are very low IME.)

Another possibility is that the installer had to dismantle the joints for some reason and transferred some rust from the threads onto the hemp in the process.
They are Henrad which is a type / brand of Stelrad. They came from a reputable merchants. But of course may be simply the plumbers choice 🙂

When radiator was replaced so was TRV and lockshield.
 
I fully intend to but thanks for calling out. Is it common for this to happen prior to a seal? Like some expansion / curing takes place? I'd personally have thought PTFE would have been used opposed to 55 and boss white.

It could have been on first heat up when everything is new etc
 
  • Like
Reactions: techweb
It could have been on first heat up when everything is new etc
Funny you say that actually... after the rad was replaced the heating was not run for a few days after as the boiler was also faulty. The system was pressurized and it was done by freezing pipes.

Is heat part of the curing process?
 

Official Sponsors of Plumbers Talk

We recommend City Plumbing Supplies, BES, and Plumbing Superstore for all plumbing supplies.