Block feed? Magnetic copper pipe!!!!!

[bananas and custard]

Further to an earlier topic of mine I've finally been up the loft armed with a magnet and sure enough I have a fatal attraction on the flow around the cold feed (not up the feed itself) which appears to be magentic for almost 6 inches upstream (boiler direction).

I have been told on this forum this could be the cause of my severe pumping over problem hence the magnet check. The pump has also started to sound at times as though it's running but not pumping then the pump seems to kick in and all sounds different.

Reading other posts is it really OK to T the feed into the vent and use this as a combined vent / feed, it's all 22mm pipework or would I be best to replace like for like?

This entire section is at least 10 feet away from the boiler so even if a temporary measure could I use plastic and JG Speedfit for the speed so I'm up and running quickly?

If I use compression fittings with jointing compound do I have to use hemp too? I've got a tub of Boss White and plumbers hemp but never used this stuff before.

Plastic would be easier if sanctioned by someone who knows.

Ta

 

[ricarbo]

It's ok if you are sure you maintain the 'hooked over the cistern' vent, unobstructed all the way from the boiler and no reverse falls, i.e. rises all the way, not necessarily vertical all the way. Plastics not within one metre of the boiler, say most boiler makers, so check installation book if possible.
Hemp not desirable on compression joints. Assemble the coupling to the (cleaned) pipe, pull the nut back from the coupling and apply a little Boss White over the olive and the male thread. Wind on the nut by hand, then finally tighten with spanner, wipe off any surplus for neat appearance. The Boss White is not theoretically needed, but is a good insurance.
Do something about the sludging - flush, clean, treat etc. Consider fitting Magnaclean to trap magnetite? Magnaclean on Plumbworld site includes video.

 

[JohnD]

If you're in a hurry, you might find it simpler (instead of changing the design) to just cut out and replace the blocked part of pipework, and poke clear any debris you can find (and preferably drain out what muck you can) prior to refilling with your chemical cleaner.

You can do the reconfiguration and flushing when it's warmer.

 

[bananas and custard]

Thanks for the advice.

If you're in a hurry, you might find it simpler (instead of changing the design) to just cut out and replace the blocked part of pipework, and poke clear any debris you can find (and preferably drain out what muck you can) prior to refilling with your chemical cleaner.

I was actually thinking that a slice in the existing vent and then T the feed in might be easier than replacing the section like for like i.e. replacing about a foot of pipe including the feed and vent T's.

I suppose my main question would be whether a combined feed and vent is strictly advisable but having seen the long thread started by PaulAH it looks as though this is OK as long as the existing vent is 22mm (my feed and vent are 22mm).

I think I'll chuck a section of plastic in for now and sort it out neat and tidy next year.

 

[JohnD]

Consider fitting Magnaclean to trap magnetite? Magnaclean on Plumbworld site includes video.

I've had a look, I like that Magnaclean. Are they really £90, though? (times is hard )

 

[ChrisR]

Just cut the pipes and scrape them out. Take the pump off and check in there for lumps of rust too. They also get stuck elsewhere - just found a 1cm diameter speroid in a motorised valve.