Can you connect microbore pipes?

FUBAR! · 7 Nov 2005

Hi can someone pls help me. I am decorating my little girls room and wish to move her single radiator from one wall to the opposite wall under the window to give her more wall space. The system is a combi boiler with all rads having thermostats. The pipework is microbore (I think 8mm not sure). The problem is that the pipework wont reach as it is, as the wall is further than where it is at present.
It it possible to join another piece of micro bore to the ends of the existing pipework under the floorboards and just run them to where I want? If so how and what do I use to join (sorry for being doofus but someone said to me you cant join microbore pipes hence my question!).
Also is it possible to do this without having to drain down all the radiators and boiler at all, as I just put 2 bottles of inhibitor in and dont want to lose it all as its bloody expensive!!
HELP!

Sorry I posted on another site so not sure if I am in right place or not with this topic

++++++++++++
Moderator's note:

I have deleted your duplicate post.
Mod Rupert
++++++++++++

Slugbabydotcom · 8 Nov 2005

Assuming your combi is a sealed system .... As most are

1. Shut all the rads off at BOTH ENDS
2. Drain the pressure from a drain off valve then close that drain off valve. [You can also do this by attaching a hose to the rad valve at step 6]
3. Disconnect the valve from one end of the rad you wish to move put a new valve [same size and turned off] on the rad so you dont lose the water from it.
4. Put a new TRV on the other end and close that off also.
5. Re-locate the rad
OK you now have two pipes with valves and the rad in the new location
6. Open one of the valves connected to the pipes over a bowl. You should find that hardly any water runs out thanks to the drinking straw effect.
7. It will then be safe to cut the pipe below the valve and extend it to the new rad valve. Only when you have connected this pipe will it be safe to do the other one.
Remember the drinking straw effect. After you have let out the pressure stored in the pressure vessel then if no air can get in then no water can get out, so make sure you only have one end open at any one time.
You should only lose a gallon or two of water and seeing as you have used 2 bottles of inhibitor this should make no measurable ill effect on your system
8. Open all your rads and re-pressurise your system.

You can extend microbore pipes but I suggest you use compression fittings or Hep20 / similar plastic if it happens to be 10 mm pipe. Soldering fittings may cause you problems bigger than you can handle.
Connecting to the rad valves as you suggest is possible but not recommended.

FUBAR! · 8 Nov 2005

Many thanks for your help

one last thing. What do I ask for to join the pipes ?

ie what are they called, is it a 8mm straight coupling joint ? I take it I need to use a solder joint as opposed to a compression one ?

ChrisR · 8 Nov 2005

Joints are no problem in solder or compression, or plastic push-fit. Just don't let a wheel-type pipe cutter block the pipe too much!

Option is to freeze - easy peasy on 8mm. Either use caps and refreeze to connect later, or put wee taps in if your new rad isn't ready. (You can use compression 15mm isolators with "reducing sets".

Smart answer is to freeze, and join on the rad valves which you will be using for your new rad, and coil the pipe up pro tem.

Fubar - not an SQL programmer were you? There was this guy....

Slugbabydotcom · 8 Nov 2005

FUBAR! said:
Many thanks for your help

one last thing. What do I ask for to join the pipes ?

ie what are they called, is it a 8mm straight coupling joint ? I take it I need to use a solder joint as opposed to a compression one ?

I edited my post while you posted that ^^^^

A solder fitting would be better but you may have a problem with the water left in the pipe. It's impossible to solder a pipe with water in it as the water turns to steam and stays at 100ºC but you need to get to about 230 something to melt the solder. If you can get the water out of the first 12 - 18 inches of the pipe then all well and good but its a lot less stressful for you to use a compression fitting

FUBAR! · 8 Nov 2005

Many thanks for the prompt replies guys. At least I know it can be done now! A friend is going to do it as he has done lots of plumbing work before including soldering and heating systems. He hasn't worked with microbore before is all, so I am sure this will let him know what he needs to do now

Michl · 25 Jun 2014

Can anyone advise on how much to tighten compression joints on micro bore pipes?

There is a small nick in one of my central heating's 8mm micro bore pipes, it's not leaking (yet) but I don't want to leave a damaged pipe under my floor... My plan is to cut out the section of pipe with the nick in it and then fit a compression joint. I know with standard (ie 15mm / 22mm) pipe, 1 to 1.5 turns after the olive bites is sufficient. I am concerned with over tightening in this case as the pipe bore is so small...

keego · 25 Jun 2014

It's possible that you are going a bit over the top with this one.
8 & 10mm pipe has quite a thick wall & if it's just a nick then it should be OK, however if you want peace of mind I would wipe a bit of solder over it rather than cutting out & putting Conex joints in.

Michl · 25 Jun 2014

It's actually a significant nick (not a scratch). I did it with a circular saw when chopping the floorboards... The plumber did try dribbling solder onto it but it didn't look like it would be very strong - it didn't stick well.

Agile · 26 Jun 2014

As you are extending the length of the pipework there is a good argument for using a larger pipe diameter so you don't increase the resistance.

If its 10 mm then perhaps not very important but if its 8 mm then I would suggest you use at least 10mm.

Tony

Michl · 26 Jun 2014

actually I wasn't going to extend the pipe work - just cut out the necessary amount eg 10mm and connect the cut ends back to together with a compression fitting

Agile · 26 Jun 2014

FUBAR! said:
The problem is that the pipework wont reach as it is, as the wall is further than where it is at present.

++++++++++++

In that case it defies my powers of imagination how you reach further away by cutting and using a compression coupler!

I am thinking of all the tubing I would have saved if I had known that!

Tony

sooey · 26 Jun 2014

Tony look at the dates. He's confused you by tagging on to an old post.

Agile · 26 Jun 2014

Well spotted! Only rarely do I fall for that !

Just demonstrates why you should NOT add to existing posts when the topic is not a continuation of the original discussion!

Tony

Michl · 26 Jun 2014

Agile said:
Well spotted! Only rarely do I fall for that !

Just demonstrates why you should NOT add to existing posts when the topic is not a continuation of the original discussion!

Tony

But there's a strong connection! Haha... sorry

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Can you connect microbore pipes?

keego

Similar threads