Tips on using microbore plumbing?

[Lobster]

I've finally decided to enter the 21st century and give microbore copper tube a go for some radiators I need to install.

I've just run a couple of lengths of the stuff roughly in place, between radiator and supply/feed pipes below the floorboards which has involved some bending around curves etc; next I need to cut off the free ends to the exact length before connecting them to the rad/pipework. (I'm using 15-10mm reducers in the TRVs/LSVs, ie compression fittings; and 15-10mm Yorkshire fittings to the pipework).

Now clearly this stuff deforms extremely easily, but I'm mindful that I need a perfectly circular section at the tips or my joints won't work. I've bought one of these gizmos so it will cut cleanly:

but am wondering about where it's been bent and straightened eg to get round corners. Is there a way of protecting the ends or something, to stop them getting deformed during installation? Or am I worrying over much?

Would welcome input from anyone who's experienced with the stuff!

David

[Peter Andrews]

Just cut a couple of inches off the end if it has deformed during installation - assuming you have enough 'slack'. Don't forget to insulate the pipes where you can and especially beneath the floors. heat loss is lower than 15 and 22mm as the surface area is less but it's still significant.

For what it's worth I've had a microbore system for over 25 years with no problems.

Peter

[Wingedcat]

won't work.

I think you're worrying too much (!) but...

I've worked with 10mm microbore and you're right, it does have a tendency to go oval when you bend it. I didn't have any awkward compression joints to make with the stuff as I used 15mm for rad-tails. Once out of sight I used soldered 15-10mm reducers and then 10mm back to the manifold. I am sure compression joints would be less forgiving than soldered joints if the pipe is deformed. I had no problems at all with my soldered joints though.

So my advice would be, try to avoid making complicated snaking runs involving a lot of bending and restraightening as you worm your way round the corners. You can always make up a series of smaller bent sections and then solder them together. Soldering 10mm is dead easy anyway, especially with Yorkshire fittings!

Luke

[Cicero]

==================== I've used 8mm for many years (10mm is similar but less fragile) without any problems. It helps greatly if you use a spring to unroll / straighten the tube. In case you're not aware of microbore springs they LOOK like this:

has a funnel at one end and obviously it goes over the tube rather than inside. I THINK that 'Tooled-up' might have their pictures mixed upbecause I've never seen a 15mm external spring. It would be worth a call to find out what 'tooled-up' are actually offering.

I've got a couple of cutters similar to the one you're showing and I've found them completely useless, perhaps because of poor quality manufacture. I always use a standard pipe cutter - the one with the round knob on the end. In the distant past I believe that a mini hacksaw was the recommended method of cutting because it doesn't close up the end of the pipe but I've never had any problems with the standard cutter.

Cic.

[kevin foote]

David,

Ihate the stuff your right to be worried it deforms and leaks much easier than the larger diameters. I would be very carefull of any bends near fittings try to not bend use 90' fittings and use a simple spring type pipe bender. Im not a plumber and I hate the 9mm stuff it just leaks al lthe time. I did some plumbing with 15mm and it was a breeze. Be carefull.

Kev

[Stuart]

9mm .??

[Antony]

It does tend to deform with a couple of inches of any bend. You can buy tools to "re-round" the tube, but I used a couple of different sized drill bits (the blunt ends, obviously). Just push in and wiggle around... Once you can get the olive/reducer on, it will tend to force the tube to a round profile. BTW I also use a smear of Fernox LSX. No leaks yet.

-Antony

[Martin Moores]

replying to Stuart, Martin Moores wrote: I have a load of 9mm microbore in my house. It's old stuff I have heard and impossible to get fittings for. I need to replace a few joints now and have had to replace loads with 10mm. If anyone knows of a supplier for 9 mm microbore please let me know.

[tabbypurr]

If I were in that position I might mandrel & hammer it out to 10mm.

NT

[The Other John]

I presume the OP means pre-metric 3/8 inch microbore which is what I've got. When I had to have a couple of TRVs and lockshield valves replaced my heating chap used 10mm fittings with extra solder and we haven't had any leaks (touch wood).

[Steve Walker]

Assuming it is copper.

My parents had a system that lasted from 1972 to about 2008 and was plumbed in 12mm, 10mm, 8mm and 6mm plastic. The only copper was the 22mm connecting boiler and pump to both floors.

Gradually more and more was replaced with copper from the mid-'90s as the plastic had become brittle and was very easily cracked if disturbed.

That meant extra work, as the original system had no lockshield valves and all but two radiators were fed and returned from a single corner (the valves had both flow and return connections and used an extension pipe within the radiator to get the feed to the far end. As copper was put in, the self-balancing of the carefully sized piepwork was disturbed and feed and return had to be separated to opposite ends of the radiators to allow lockshields to be fitted.

SteveW

[The Other John]

That sounds like the Amtek (?) kit I installed about the same time. Fortunately we moved before it needed repairs!

[harry]

As it's eleven years old,I 'spect the problem has been resolved.

[DerbyBorn]

The Lockshield was under a domed cover and was a screw. I thought they were quite good - but never a thermostatic version so they were doomed.

[Steve Walker]

This system didn't have lockshields at all. One valve per radiator and it had an inlet (with handwheel) and outlet (right next to the inlet).

See

Balancing was pre-calculated sizing of the pipes to each radiator - for instance, from memory, the hall radiator (close to the pump and return) was a very large double panel radiator, connected with two 6mm pipes, whereas the bathroom radiator (most distant) was a small, single panel radiator, fed with two 10mm pipes.

SteveW

[DerbyBorn]

Steve Walker wrote in news:ouii0p$ld7$ [e-mail]:

Sorry - never seen that one before - I believe mine were called Twinfast Valves and all had a balancing screw. I think the last ones were used when my house was built in 1988. Had one fracture (the actual casting) and had hell of a job finding one. Ended up in the scrap pile at a local plumbers to remove one from an old radiator.

[Steve Walker]

That's fair enough, the ones you had made for a simpler system. The ones my parents had didn't require any adjustment to balance the system, but did require full calculation of the installation beforehand to ensure that the system was balanced by pipe lengths and bores.

SteveW