I'm going to start installing a central heating system next week and had
planned to used conventional 15mm pipe of which I already have experience
of. Hoewever, I now realise that 8mm and 10mm pipe is widely available.
Now I'm thinking that 8mm pipe will be much easier to manipulate and lay
than 15mm? It's also cheaper and the fittings, valves, joints etc seem to be
widely available. I've also heard that it makes the system more efficient.
Does it all work in the same way as 15mm? Are there any problems that arise
from using this size? Are there any advantages between 8mm and 10mm?
Also, I'm assuming that to connect the system to the boiler I just use a
15mm to 8mm/10mm adaptor?
Thanks for any help
Chris
You can buy various types of manifold so do a bit of 'googling' for some
ideas. An alternative to manifolds is to use 22mm feed and return with
suitable reducers (22mm / 15mm /8mm) to make the radiator connections. This
sounds a bit complicated but it can provide more flexibility in layout and
shorter runs of 8mm than single manifolds.
Greater efficiency is based mainly on the fact that there is less water in
the system because of the smaller pipework. I think that this is a bit of a
myth because most of the water is in the radiators rather than the pipework.
The choice between 8mm / 10mm depends on various possibilities. Smaller
pipework is more likely to get blocked by sludge etc. but a good inhibitor
should prevent this.
If you go ahead buy an external spring to straighten and shape your pipe.
Both 8mm and 10mm come in a roll so you will have to un-coil it as you go.
Enough to start with - I guess others will add to or improve on what I've
said.
Cic.
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I went for 22mm to manifolds at each floor, then ran 8mm from those to
individual rads. All the 8mm runs were about the same length - if any
had been significantly longer, I would have run it in 10mm.
I went for thermostatically controlled radiator valves.
Seems to work ok but a rug in front of an open log fire is better for
toasting crumpets. ;)
--
Sue
You are slightly in error in thinking a microbore system is exactly
the same as a 15mm one, it's not. A 15mm pipe has a heat carrying
capacity of about 4Kw, but 10mm and 8mm is considerably less and you
should not have more than one rad on these pipes. This means that each
rad has it's own flow and return from a central point where they join
into a thing called a manifold. The manifold is usually 22mm copper
and there is one for all the flows and one for the returns, the
manifolds go to the boiler in 22mm pipeing.
If you can imagine two 22mm pipes going from the boiler to a
convenient point and ending in two manifolds. The 8mm or 10mm pipe
then comes from spiggots on each manifold to each rad.
A couple of small rads can be put on one micro flow and return, if the
heat requirement is low.
As you have probably worked out, a microbore system is hideous to look
at unless concealed under a floor or something.
chris
"Chris Long" <c.a....@ntlworld.com> wrote in message
news:359yg.48$WY2...@newsfe3-gui.ntli.net...
http://www.heatandplumb.com/acatalog/Brass_Manifolds_.html
or here:
http://www.toolstation.com/shop/Plumbing&Heating/EndFeed/d20/sd2698
My earlier suggestion would use these two soldered together :
http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=100555&ts=73048&id=11704
http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=100555&ts=73087&id=19390
Cic.
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Yorkshire Fittings manufacture the manifolds.They have an excellent
site showing their complete range of fittings.Can1t remember if is .com
or co.uk
Mark.
>
================================
This is it - very good.
http://www.yorkshirefittings.co.uk/index.cfm
Cic.
>
> "Chris Long" <c.a....@ntlworld.com> wrote in message
> news:359yg.48$WY2...@newsfe3-gui.ntli.net...
> > hi
> >
> > I'm going to start installing a central heating system next week and had
> > planned to used conventional 15mm pipe of which I already have experience
> > of. Hoewever, I now realise that 8mm and 10mm pipe is widely available.
> >
> > Now I'm thinking that 8mm pipe will be much easier to manipulate and lay
> > than 15mm? It's also cheaper and the fittings, valves, joints etc seem to
> >
> >
> ===============================
> Your boiler will have 22mm connections so all the pipework around the boiler
> will also be 22mm (possibly some 15mm - look in boiler manual). The 22mm
> pipe will connect to a manifold from which the 8mm (or 10mm) will emerge and
> return.
>
> You can buy various types of manifold so do a bit of 'googling' for some
> ideas. An alternative to manifolds is to use 22mm feed and return with
> suitable reducers (22mm / 15mm /8mm) to make the radiator connections. This
> sounds a bit complicated but it can provide more flexibility in layout and
> shorter runs of 8mm than single manifolds.
>
> Greater efficiency is based mainly on the fact that there is less water in
> the system because of the smaller pipework. I think that this is a bit of a
> myth because most of the water is in the radiators rather than the pipework.
>
> The choice between 8mm / 10mm depends on various possibilities. Smaller
> pipework is more likely to get blocked by sludge etc. but a good inhibitor
> should prevent this.
>
> If you go ahead buy an external spring to straighten and shape your pipe.
> Both 8mm and 10mm come in a roll so you will have to un-coil it as you go.
>
> Enough to start with - I guess others will add to or improve on what I've
> said.
There are also limitations on pipe length. The bigger the rad, the
shorter the permissible run. For 8mm its less than 10mm, which of course
is less than 15mm. You can also run into issues with the pump not being
powerful enough to push the water through because the smaller pipes have
a MUCH greater resistance.
My suggestion, if you don't understand all that, is to stick with the
15mm, but consider using plastic pipe. Its so much easier to work with.
If you war to persist with microbore, a Google into uk.d-i-y should get
you started, and a post there would get you more specific responses.
Phil
The uk.d-i-y FAQ is at http://www.diyfaq.org.uk/
The Google uk.d-i-y archive is at http://tinyurl.com/65kwq
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