Radiator extension tails.

[Tristar]

Hi guys,

Nearing the end of my conservatory construction saga, (started in mid March, details of which can be read on the appropriate site when you have a spare hour).

I now have a problem with connecting the radiators, thanks to the screed layer managing to move my carefully fixed up-pipes, such that they are now wider than required, and tiles laid prevent adjusting them back to the required width. I know that there are two extension tails, union and compression, available at Screwfix, and possibly other types elsewhere.

My question, what is the best/correct type to allow connection from a conventional female radiator thread to either the conventional lockshield valve with the large compression connection, or to a thermostatic valve, which has a 15mm compression connection. The extension can go to either valve. One radiator needs a 20mm extension, the other, only 12mm. Unfortunately, as the rads are low to the floor, there is very little latitude for movement.

Thank you

 

[seco services]

this will fit a
conventional lockshield valve

http://www.screwfix.com/search.do;j...FQ?_dyncharset=UTF-8&fh_search=17552&x=4&y=12

this will fit a trv

http://www.screwfix.com/search.do;j...FQ?_dyncharset=UTF-8&fh_search=15531&x=8&y=10

 

[gas4you]

Extensions are available in 10, 20, 30 or 40mm lengths.

 

[Tristar]

Thanks very much guys,

Seco, I have got one of the Screwfix compression tails from a friend, (not a plumber unfortunately) but I am at a loss to know how the seal is made into the radiator. I have looked at it closely, and the loose male threaded nut has an internal seal against the inner tube, but no apparent way of ensuring its seal when screwed into the radiator, other than the rubber o-ring bearing against the belled pipe end. Is this adequate to seal one bar plus pressure? I will try it tomorrow and let you know.

PS, Strange to bell the end as if to fit to an olive, when it is designed to screw into a radiator. Have I got the right idea?

 

[Tristar]

Have now fitted the Screwfix compression extension piece, and was not surprised that it leake between the nut (into the rad) and the pipe. Have now used a fixed extension which is fine.

I now need a 10mm piece to extend my second rad, but the fixed ones, although nominally 10mm, are about 18mm, and I need 10mm only. Is anything like this available?

Cheers

 

[JPC]

yes PTS do extensions that simply extend the fenale thread from the rad...in 10-20-30 and 40 i think...cant find a link...but you could try for a PTS near you

 

[Tristar]

Thanks Jamie. Yes it is a PTS spacer I'm using, but they still don't do one small enough. The problem is that these are v. low rads in a conservatory, and the pipes are only about 120mm high with v. little room for movement. I will work something out.

Thanks for all your help.

Cheers.

 

[big1belly]

I've been experimenting with these connectors for the last 2 years and theres a few tips. Firstly, the basic constuction of these is an 'oyster' style connector. a 15mm tube inside an 'o-ring' seal. So you can extend these if you want by replacing the exisiting tube with any length of 15mm copper pipe. Just crimp or expand the inner end of the new pipe after it is inserted so it cannot be pulled out. I usually expand it using a round steel and just rotate it against the inner pipe wall a few times. Does not take much. The travel is always limited by the distance that the pipe can travel inside the radiator.. about 40mm.
I have extended to 150mm in vertical and 100mm in horizontal.

In terms of the seal against the radiator.. its obviously a face seal o-ring which does the business here. O-rings 'should' provide a superior seal to any other type of connector. They are used in industry to very high pressures, temperatures and agressive fluids. The same sort of seal is also used on rad bleed and stop valves nowadays.

However.. the smoothness and fit of the o'ring on the radiator face is critical.
A smooth and even mating surface on the rad with around 3mm of steel on the face around the rad threads is ideal.. and especially no champher on the start of the inner radiator threads. UK Rads are designed to have a threaded inner seal and many manufacturers have no consistent manufacture for a mating surface. I used rads from Stelrad, B&Q, a many which have funny foreign names on them.

If there is a large champher or less than 3mm face seal.. consider replacing the o-ring with one from a bleed valve. These are always a little fatter .. and actually work better. I am investigating a source of fatter o-rings.
Also.. always remove the paint from the mating surface. I have found a 10% long term failure rate with the connectors if you do not remove the paint. I use a file and create a dead smooth and clean surface. I now do the same for the bleed and stop valves. Thats 10mins well invested.
I smear silicon grease on the threads and mating surface. Tighten till o'ring touches the surface then quarter turn. Thats it.

The connectors always work.. they never ever leak.. as long as you have a smooth mating surface to the 'o-ring'. Also, because the connector can extend after its installed, there is no long term leakage. As the rad expands and contracts, the tails move with it. No movement of the unions.

I now use these tails for all my radiator installs as the look really neat and I am mostly replacing old rads.

 

[keego]

Have now fitted the Screwfix compression extension piece, and was not surprised that it leake between the nut (into the rad) and the pipe. Have now used a fixed extension which is fine.

I now need a 10mm piece to extend my second rad, but the fixed ones, although nominally 10mm, are about 18mm, and I need 10mm only. Is anything like this available?

Cheers

Try using a lockshield with drain off that shouldn't be too far off what you need.

 

[big1belly]

Yer.. I use drainoffs as well. but only on bottom floor rads and when they are against a wall. Underneath a window I want to keep the rad -exactly- central. In that case (the majority of the rad replacements I do) I use an extension on both sides.