I've got a plumber in doing some jobs for me at the moment, including
fitting some new radiators to an existing system, which has a combi
boiler and 22/15mm copper pipes throughout. I left him to it this
morning and came back to find he'd installed a rad using 10mm
microbore; he'd put the 15mm TRV and lockshield valve which I'd
supplied to one side, and bought his own 10mm kit instead.

I am admittedly predjudiced against microbore as it's harder (IMO, for
me) to fit, and I believe more likely to block; so I was a bit hacked
off with this, especially as there was no problem at all with access
to existing 15mm pipework under the floor. He'd simply fitted lengths
of microbore to the ends of the flow and return 15mm pipes using
reducers.

When quizzed, he said it was because radiators "work better" with
microbore; that's as much as I could get. The guy is very
uncommunicative and I find difficult to talk to, but he's reliable,
good value, and does a good job, and I don't want to make an issue of
this unnecessarily. But before he fits any more rads for me can
anybody tell me if it's possible there is any truth in what he's
saying?

Thanks
David

On 5 Apr 2004 16:13:32 -0700, in uk.d-i-y
(Lobster) strung together this:

I've got a plumber in doing some jobs for me at the moment, including
fitting some new radiators to an existing system, which has a combi
boiler and 22/15mm copper pipes throughout. I left him to it this
morning and came back to find he'd installed a rad using 10mm
microbore; he'd put the 15mm TRV and lockshield valve which I'd
supplied to one side, and bought his own 10mm kit instead.

I am admittedly predjudiced against microbore as it's harder (IMO, for
me) to fit, and I believe more likely to block; so I was a bit hacked
off with this, especially as there was no problem at all with access
to existing 15mm pipework under the floor. He'd simply fitted lengths
of microbore to the ends of the flow and return 15mm pipes using
reducers.

When quizzed, he said it was because radiators "work better" with
microbore; that's as much as I could get. The guy is very
uncommunicative and I find difficult to talk to, but he's reliable,
good value, and does a good job, and I don't want to make an issue of
this unnecessarily. But before he fits any more rads for me can
anybody tell me if it's possible there is any truth in what he's
saying?

There is an advantage in the use of microbore in that the system will
heat up quicker because there is less water in it. I wouldn't say it
was 'better' overall, If the 15mm was local to the rad I would have
done it all in 15mm.
--

SJW
A.C.S. Ltd.

Subject: Microbore CH better than 15mm - says plumber
From: (Lobster)
Date: 06/04/04 00:13 GMT Daylight Time
Message-id:

I've got a plumber in doing some jobs for me at the moment, including
fitting some new radiators to an existing system, which has a combi
boiler and 22/15mm copper pipes throughout. I left him to it this
morning and came back to find he'd installed a rad using 10mm
microbore; he'd put the 15mm TRV and lockshield valve which I'd
supplied to one side, and bought his own 10mm kit instead.

I am admittedly predjudiced against microbore as it's harder (IMO, for
me) to fit, and I believe more likely to block; so I was a bit hacked
off with this, especially as there was no problem at all with access
to existing 15mm pipework under the floor. He'd simply fitted lengths
of microbore to the ends of the flow and return 15mm pipes using
reducers.

When quizzed, he said it was because radiators "work better" with
microbore; that's as much as I could get. The guy is very
uncommunicative and I find difficult to talk to, but he's reliable,
good value, and does a good job, and I don't want to make an issue of
this unnecessarily. But before he fits any more rads for me can
anybody tell me if it's possible there is any truth in what he's
saying?

No it's ********. Nothing can work "better" with less flow. It's easier to bend
and fit of course and when time is money that's of the essence. Whether it'll
actually harm your system is another matter. If the flow to the rads is
sufficient and they all get hot then it's fine.


Dave Baker - Puma Race Engines (www.pumaracing.co.uk)
I'm not at all sure why women like men. We're argumentative, childish,
unsociable and extremely unappealing naked. I'm quite grateful they do though.

On 5 Apr 2004 16:13:32 -0700, (Lobster)
wrote:

I've got a plumber in doing some jobs for me at the moment, including
fitting some new radiators to an existing system, which has a combi
boiler and 22/15mm copper pipes throughout. I left him to it this
morning and came back to find he'd installed a rad using 10mm
microbore; he'd put the 15mm TRV and lockshield valve which I'd
supplied to one side, and bought his own 10mm kit instead.

I am admittedly predjudiced against microbore as it's harder (IMO, for
me) to fit, and I believe more likely to block;

Not really. If the system is neglected such that there is sludge
build up sufficient to clog microbore then it is going to be expensive
quite soon.


so I was a bit hacked
off with this, especially as there was no problem at all with access
to existing 15mm pipework under the floor. He'd simply fitted lengths
of microbore to the ends of the flow and return 15mm pipes using
reducers.

When quizzed, he said it was because radiators "work better" with
microbore; that's as much as I could get. The guy is very
uncommunicative and I find difficult to talk to, but he's reliable,
good value, and does a good job, and I don't want to make an issue of
this unnecessarily. But before he fits any more rads for me can
anybody tell me if it's possible there is any truth in what he's
saying?

The one thing that you can say is that it makes the control obtained
by the lockshield valve a little more fine-grained, simply because the
flow is reduced slightly in comparison to 15mm. However, on a short
length of 10mm this will hardly be noticable.

Other than that there is no reason not to mix and match microbore with
15mm provided that sizing is adequate - but that applies to 15mm as
well.






Thanks
David

..andy

To email, substitute .nospam with .gl

Dave Baker wrote:

No it's ********. Nothing can work "better" with less flow. It's easier to bend
and fit of course and when time is money that's of the essence. Whether it'll
actually harm your system is another matter. If the flow to the rads is
sufficient and they all get hot then it's fine.

You also can run into limitations if you are talking about radiators
with a very large heat output - there comes a point where the microbore
will not have the heat supply capacity to get the designed output from
the radiator.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Subject: Microbore CH better than 15mm - says plumber
From: John Rumm
Date: 06/04/04 01:17 GMT Daylight Time
Message-id:

Dave Baker wrote:

No it's ********. Nothing can work "better" with less flow. It's easier to
bend
and fit of course and when time is money that's of the essence. Whether
it'll
actually harm your system is another matter. If the flow to the rads is
sufficient and they all get hot then it's fine.

You also can run into limitations if you are talking about radiators
with a very large heat output - there comes a point where the microbore
will not have the heat supply capacity to get the designed output from
the radiator.

In which case the rad won't get hot as I said.


Dave Baker - Puma Race Engines (www.pumaracing.co.uk)
I'm not at all sure why women like men. We're argumentative, childish,
unsociable and extremely unappealing naked. I'm quite grateful they do though.

"Lobster" wrote in message
om...
I've got a plumber in doing some jobs for me at the moment, including
fitting some new radiators to an existing system, which has a combi
boiler and 22/15mm copper pipes throughout. I left him to it this
morning and came back to find he'd installed a rad using 10mm
microbore; he'd put the 15mm TRV and lockshield valve which I'd
supplied to one side, and bought his own 10mm kit instead.

I am admittedly predjudiced against microbore as it's harder (IMO, for
me) to fit, and I believe more likely to block; so I was a bit hacked
off with this, especially as there was no problem at all with access
to existing 15mm pipework under the floor. He'd simply fitted lengths
of microbore to the ends of the flow and return 15mm pipes using
reducers.

When quizzed, he said it was because radiators "work better" with
microbore; that's as much as I could get. The guy is very
uncommunicative and I find difficult to talk to, but he's reliable,
good value, and does a good job, and I don't want to make an issue of
this unnecessarily. But before he fits any more rads for me can
anybody tell me if it's possible there is any truth in what he's
saying?

David,

If in the south your opinion is skewed. Microbore is alien to the hard
water south, while in Northern soft water areas it is the norm. The
Scandinavians have been using it since the end of WW2, and the north of
England the late 1960s. The south would not even install microbore in
"sealed" systems, simply because they just didn't understand it.

Microbore is superior if the whole system is designed for it with
appropriate manifolds. I assume you do not have a full microbore system.
10mm pipe is common on small-bore systems (15mm & 22mm) on some rad runs.

Nothing to worry about, especially if the system is sealed.

"Dave Baker" wrote in message
...
Subject: Microbore CH better than 15mm - says plumber
From: (Lobster)
Date: 06/04/04 00:13 GMT Daylight Time
Message-id:

I've got a plumber in doing some jobs for me at the moment, including
fitting some new radiators to an existing system, which has a combi
boiler and 22/15mm copper pipes throughout. I left him to it this
morning and came back to find he'd installed a rad using 10mm
microbore; he'd put the 15mm TRV and lockshield valve which I'd
supplied to one side, and bought his own 10mm kit instead.

I am admittedly predjudiced against microbore as it's harder (IMO, for
me) to fit, and I believe more likely to block; so I was a bit hacked
off with this, especially as there was no problem at all with access
to existing 15mm pipework under the floor. He'd simply fitted lengths
of microbore to the ends of the flow and return 15mm pipes using
reducers.

When quizzed, he said it was because radiators "work better" with
microbore; that's as much as I could get. The guy is very
uncommunicative and I find difficult to talk to, but he's reliable,
good value, and does a good job, and I don't want to make an issue of
this unnecessarily. But before he fits any more rads for me can
anybody tell me if it's possible there is any truth in what he's
saying?

No it's ********.

Please only comment if you know what you are talking about.

"John Rumm" wrote in message
...
Dave Baker wrote:

No it's ********. Nothing can work "better" with less flow. It's easier
to bend
and fit of course and when time is money that's of the essence. Whether
it'll
actually harm your system is another matter. If the flow to the rads is
sufficient and they all get hot then it's fine.

You also can run into limitations if you are talking about radiators
with a very large heat output - there comes a point where the microbore
will not have the heat supply capacity to get the designed output from
the radiator.

You size the pipe to suit. As always.

"Dave Baker" wrote in message
...
Subject: Microbore CH better than 15mm - says plumber
From: John Rumm
Date: 06/04/04 01:17 GMT Daylight Time
Message-id:

Dave Baker wrote:

No it's ********. Nothing can work "better" with less flow. It's easier
to
bend
and fit of course and when time is money that's of the essence. Whether
it'll
actually harm your system is another matter. If the flow to the rads is
sufficient and they all get hot then it's fine.

You also can run into limitations if you are talking about radiators
with a very large heat output - there comes a point where the microbore
will not have the heat supply capacity to get the designed output from
the radiator.

In which case the rad won't get hot as I said.

Please do not comment on issues you clearly know nothing about. Stick to
engines that go Brummmm, brummmm.

"IMM" wrote in message
...

David,

If in the south your opinion is skewed. Microbore is alien to the
hard
water south, while in Northern soft water areas it is the norm. The
Scandinavians have been using it since the end of WW2, and the north
of
England the late 1960s. The south would not even install microbore in
"sealed" systems, simply because they just didn't understand it.

Microbore is superior if the whole system is designed for it with
appropriate manifolds. I assume you do not have a full microbore
system.
10mm pipe is common on small-bore systems (15mm & 22mm) on some rad
runs.

Nothing to worry about, especially if the system is sealed.



What are you talking about? I live in the south, and I don't have hard
water. My parents live in the south and their radiators are all on
microbore.

Neil

IMM wrote:
"Lobster" wrote in message
om...
I've got a plumber in doing some jobs for me at the moment, including
fitting some new radiators to an existing system, which has a combi
boiler and 22/15mm copper pipes throughout. I left him to it this
morning and came back to find he'd installed a rad using 10mm
microbore; he'd put the 15mm TRV and lockshield valve which I'd
supplied to one side, and bought his own 10mm kit instead.

I am admittedly predjudiced against microbore as it's harder (IMO,
for me) to fit, and I believe more likely to block; so I was a bit
hacked off with this, especially as there was no problem at all with
access to existing 15mm pipework under the floor. He'd simply fitted
lengths of microbore to the ends of the flow and return 15mm pipes
using reducers.

When quizzed, he said it was because radiators "work better" with
microbore; that's as much as I could get. The guy is very
uncommunicative and I find difficult to talk to, but he's reliable,
good value, and does a good job, and I don't want to make an issue of
this unnecessarily. But before he fits any more rads for me can
anybody tell me if it's possible there is any truth in what he's
saying?

David,

If in the south your opinion is skewed. Microbore is alien to the
hard water south, while in Northern soft water areas it is the norm.
The Scandinavians have been using it since the end of WW2, and the
north of England the late 1960s. The south would not even install
microbore in "sealed" systems, simply because they just didn't
understand it.

Microbore is superior if the whole system is designed for it with
appropriate manifolds. I assume you do not have a full microbore
system. 10mm pipe is common on small-bore systems (15mm & 22mm) on
some rad runs.

Nothing to worry about, especially if the system is sealed.

A memorable quote is appropriate here - you yourself may find it familiar:

"Please do not comment on issues you clearly know nothing about."

Living in the South (Surrey) I can confirm that plenty of people here have
microbore.

(different) David

"Neil Jones" wrote in message
...

"IMM" wrote in message
...

David,

If in the south your opinion is skewed. Microbore is alien to the
hard
water south, while in Northern soft water areas it is the norm. The
Scandinavians have been using it since the end of WW2, and the north
of
England the late 1960s. The south would not even install microbore in
"sealed" systems, simply because they just didn't understand it.

Microbore is superior if the whole system is designed for it with
appropriate manifolds. I assume you do not have a full microbore
system.
10mm pipe is common on small-bore systems (15mm & 22mm) on some rad
runs.

Nothing to worry about, especially if the system is sealed.

What are you talking about?

It was quite clear.

I live in the south, and I don't have hard
water. My parents live in the south and their radiators are all on
microbore.

There are few soft water areas in the south. And fewer full microbore
systems. You are one of the few. Don't you feel good about that?

"David Hearn" wrote in message
...
IMM wrote:
"Lobster" wrote in message
om...
I've got a plumber in doing some jobs for me at the moment, including
fitting some new radiators to an existing system, which has a combi
boiler and 22/15mm copper pipes throughout. I left him to it this
morning and came back to find he'd installed a rad using 10mm
microbore; he'd put the 15mm TRV and lockshield valve which I'd
supplied to one side, and bought his own 10mm kit instead.

I am admittedly predjudiced against microbore as it's harder (IMO,
for me) to fit, and I believe more likely to block; so I was a bit
hacked off with this, especially as there was no problem at all with
access to existing 15mm pipework under the floor. He'd simply fitted
lengths of microbore to the ends of the flow and return 15mm pipes
using reducers.

When quizzed, he said it was because radiators "work better" with
microbore; that's as much as I could get. The guy is very
uncommunicative and I find difficult to talk to, but he's reliable,
good value, and does a good job, and I don't want to make an issue of
this unnecessarily. But before he fits any more rads for me can
anybody tell me if it's possible there is any truth in what he's
saying?

David,

If in the south your opinion is skewed. Microbore is alien to the
hard water south, while in Northern soft water areas it is the norm.
The Scandinavians have been using it since the end of WW2, and the
north of England the late 1960s. The south would not even install
microbore in "sealed" systems, simply because they just didn't
understand it.

Microbore is superior if the whole system is designed for it with
appropriate manifolds. I assume you do not have a full microbore
system. 10mm pipe is common on small-bore systems (15mm & 22mm) on
some rad runs.

Nothing to worry about, especially if the system is sealed.

A memorable quote is appropriate here - you yourself may find it familiar:

"Please do not comment on issues you clearly know nothing about."

Living in the South (Surrey) I can confirm that plenty of people here have
microbore.

Full systems or microbore (soft copper) runs to individual rads? A full
mircobore system has manifolds, etc. There are some in the south but few
and between. Most would have been fitted by a developers. Get a small
local company to do it, and they would shy away as they would not be
familiar.

John Rumm wrote:
Dave Baker wrote:

No it's ********. Nothing can work "better" with less flow. It's
easier to bend
and fit of course and when time is money that's of the essence.
Whether it'll
actually harm your system is another matter. If the flow to the rads is
sufficient and they all get hot then it's fine.


You also can run into limitations if you are talking about radiators
with a very large heat output - there comes a point where the microbore
will not have the heat supply capacity to get the designed output from
the radiator.


Indeed. I calculated that the maximum heat transfer through 1m of 8mm
pipe is 2.28Kw and obviously less through longer pipes so any rad over
2Kw (ie a fairly 'normal 600 x 1200 double) would not reach temperature
if fed with microbore

Nick Brooks

"IMM" wrote in message
...

"David Hearn" wrote in message
...

"Please do not comment on issues you clearly know nothing about."

Living in the South (Surrey) I can confirm that plenty of people
here have
microbore.

Full systems or microbore (soft copper) runs to individual rads? A
full
mircobore system has manifolds, etc. There are some in the south but
few
and between. Most would have been fitted by a developers.

Even if this were true, wouldn't the developer have used a local subbie
to install the heating?

Get a small
local company to do it, and they would shy away as they would not be
familiar.

"IMM" wrote in message
...

"Neil Jones" wrote in message
...

"IMM" wrote in message
...

David,

If in the south your opinion is skewed. Microbore is alien to the
hard
water south, while in Northern soft water areas it is the norm.
The
Scandinavians have been using it since the end of WW2, and the
north
of
England the late 1960s. The south would not even install
microbore in
"sealed" systems, simply because they just didn't understand it.

Microbore is superior if the whole system is designed for it with
appropriate manifolds. I assume you do not have a full microbore
system.
10mm pipe is common on small-bore systems (15mm & 22mm) on some
rad
runs.

Nothing to worry about, especially if the system is sealed.

What are you talking about?

It was quite clear.

I live in the south, and I don't have hard
water. My parents live in the south and their radiators are all on
microbore.

There are few soft water areas in the south.

I couldn't say - so I wouldn't like to generalise.

And fewer full microbore
systems. You are one of the few. Don't you feel good about that?

Fabulous, thanks :-)

Neil

But before he fits any more rads for me can anybody tell me if
it's possible there is any truth in what he's saying?

As the runs of microbore are short (and assuming the radiators are of a
normal size) the main difference will be in appearance. I tend to prefer the
look of 15mm myself, particularly if done in chromed pipe when visible.

If the system is done mainly in microbore, perhaps with a manifold system,
then pipe sizing becomes much more critical and has to be carefully
calculated.

Christian.

"Neil Jones" wrote in message
...

"IMM" wrote in message
...

"David Hearn" wrote in message
...

"Please do not comment on issues you clearly know nothing about."

Living in the South (Surrey) I can confirm that plenty of people
here have
microbore.

Full systems or microbore (soft copper) runs to individual rads? A
full
mircobore system has manifolds, etc. There are some in the south but
few
and between. Most would have been fitted by a developers.

Even if this were true, wouldn't the developer have used a local subbie
to install the heating?

To their design and drawings provided for them to follow.

"Nick Brooks" wrote in message
...
John Rumm wrote:
Dave Baker wrote:

No it's ********. Nothing can work "better" with less flow. It's
easier to bend
and fit of course and when time is money that's of the essence.
Whether it'll
actually harm your system is another matter. If the flow to the rads is
sufficient and they all get hot then it's fine.


You also can run into limitations if you are talking about radiators
with a very large heat output - there comes a point where the microbore
will not have the heat supply capacity to get the designed output from
the radiator.


Indeed. I calculated that the maximum heat transfer through 1m of 8mm
pipe is 2.28Kw

About 2.5kW.

and obviously less through longer pipes so any rad over
2Kw (ie a fairly 'normal 600 x 1200 double) would not reach temperature
if fed with microbore

Not true. The pipe run is sized to suit. A decent length of 8mm pipe can
provide enough heat for a 2.5kW rad with flow/return temp differential of
11C. If running a condensing boiler on the system at 20C differential then
approx 4kW of heat will be delivered down a 8mm pipe.

On Tue, 06 Apr 2004 10:57:20 +0100, Nick Brooks
wrote:

John Rumm wrote:
Dave Baker wrote:

No it's ********. Nothing can work "better" with less flow. It's
easier to bend
and fit of course and when time is money that's of the essence.
Whether it'll
actually harm your system is another matter. If the flow to the rads is
sufficient and they all get hot then it's fine.


You also can run into limitations if you are talking about radiators
with a very large heat output - there comes a point where the microbore
will not have the heat supply capacity to get the designed output from
the radiator.


Indeed. I calculated that the maximum heat transfer through 1m of 8mm
pipe is 2.28Kw and obviously less through longer pipes so any rad over
2Kw (ie a fairly 'normal 600 x 1200 double) would not reach temperature
if fed with microbore

Nick Brooks

It's 10mm here.......


..andy

To email, substitute .nospam with .gl

On Tue, 6 Apr 2004 10:52:14 +0100, "IMM" wrote:


.

Full systems or microbore (soft copper) runs to individual rads? A full
mircobore system has manifolds, etc. There are some in the south but few
and between. Most would have been fitted by a developers. Get a small
local company to do it, and they would shy away as they would not be
familiar.


You're generalising again.

I have an 8mm system with several manifolds. I live in the south and
it works well.

I know at least two heating engineers in the area who fit them.....



..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Tue, 6 Apr 2004 10:52:14 +0100, "IMM" wrote:


.

Full systems or microbore (soft copper) runs to individual rads? A full
mircobore system has manifolds, etc. There are some in the south but few
and between. Most would have been fitted by a developers. Get a small
local company to do it, and they would shy away as they would not be
familiar.


You're generalising again.

I have an 8mm system with several manifolds. I live in the south and
it works well.

Fiited with the house no doubt.

I know at least two heating engineers in the area who fit them.....

You do? You are lucky then.

Andy Hall wrote:
On Tue, 06 Apr 2004 10:57:20 +0100, Nick Brooks
wrote:


John Rumm wrote:

Dave Baker wrote:


No it's ********. Nothing can work "better" with less flow. It's
easier to bend
and fit of course and when time is money that's of the essence.
Whether it'll
actually harm your system is another matter. If the flow to the rads is
sufficient and they all get hot then it's fine.


You also can run into limitations if you are talking about radiators
with a very large heat output - there comes a point where the microbore
will not have the heat supply capacity to get the designed output from
the radiator.



Indeed. I calculated that the maximum heat transfer through 1m of 8mm
pipe is 2.28Kw and obviously less through longer pipes so any rad over
2Kw (ie a fairly 'normal 600 x 1200 double) would not reach temperature
if fed with microbore

Nick Brooks


It's 10mm here.......


.andy

To email, substitute .nospam with .gl

Doh! missed that - time to get the calculator out again

Nick

On Tue, 6 Apr 2004 11:54:24 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Tue, 6 Apr 2004 10:52:14 +0100, "IMM" wrote:


.

Full systems or microbore (soft copper) runs to individual rads? A full
mircobore system has manifolds, etc. There are some in the south but few
and between. Most would have been fitted by a developers. Get a small
local company to do it, and they would shy away as they would not be
familiar.


You're generalising again.

I have an 8mm system with several manifolds. I live in the south and
it works well.

Fiited with the house no doubt.

I specified 8mm microbore and the use of a specific contractor that I
knew.



I know at least two heating engineers in the area who fit them.....

You do? You are lucky then.

I think that they are actually.


..andy

To email, substitute .nospam with .gl

Other than that there is no reason not to mix and match microbore with
15mm provided that sizing is adequate - but that applies to 15mm as
well.

Does this apply across a single radiator ? I recently moved one which
had short runs of microbore to connect the rad to the main 15mm pipe
runs. On the input side, I was able to re-use the existing microbore
but on the return side I couldn't and ended up with a temporary bodge
using 15mm pipe fittings which I had plenty of. I wasn't able to get
hold of any microbore at the time and 'bodged' it simply so that I
could the rest of the house heated. I had always planned on
revisiting this, but as the system is working it has dropped down my
list of priorities. I may be imagining it but I don't believe I am
getting the same heat output fromt the radiator as I did before.

Should I leave everything as is, replace the microbore on the input
side with 15mm fittings or replace the 15mm fittings on the return
side with microbore.

Thanks.

Should I leave everything as is, replace the microbore on the input
side with 15mm fittings or replace the 15mm fittings on the return
side with microbore.

You should find the heat output will stay the same or fractionally improve
with 15mm instead of microbore for one leg. The only reason to replace the
pipework is aesthetic. If the output has dropped, it is probably because the
lockshield wasn't set to the same position. Open it a fraction.

If you do replace the pipework, just change the end that will make it look
nicer, provided the microbore was sufficient before. If the radiator never
really got hot enough, even with the lockshield fully open, replace with
15mm.

Christian.

10mm is fine. It is very usual to bring 10mm to rads from a 15mm feed which
in turn comes from a 22mm flow and return. 10mm is also very easy to work
with on a DIY basis. All you need is a hand held bender and you're away.
It's easier to install than 15mm in many places. Fittings are more expensive
though. As for the TRV.... he could have used a 15-10mm resucer and used
your TRV so make sure he don't try and charge you for his one. A swap sounds
fair though - he may not have had a reducer so fair enough. These days 10mm
is used for many other things such as tap feeds. Brand new houses have 10mm
tap feeds coming from a 15mm pipe. I used 10mm a lot in my new build. You
simply don't need the flow of 15mm unless it's the likes of a bath or
shower.

(Lobster) wrote
I left him [plumber] to it this
morning and came back to find he'd installed a rad using 10mm
microbore; he'd put the 15mm TRV and lockshield valve which I'd
supplied to one side, and bought his own 10mm kit instead.

I am admittedly predjudiced against microbore as it's harder (IMO, for
me) to fit, and I believe more likely to block; so I was a bit hacked
off with this, especially as there was no problem at all with access
to existing 15mm pipework under the floor. He'd simply fitted lengths
of microbore to the ends of the flow and return 15mm pipes using
reducers.

Keep an eye on things (but don't hawk over his shoulder) and be very
specific if you want him to do something in a certain way.

I went out and 'left a plumber to it' and I too was a bit hacked off
with the results.

He'd used pushfit where i'd wanted him to install solder fittings
(under a floor I was going to tile over). And up to the point I left
he had been doing at my request.

He went away, the pushfit is still under there and I won't be
re-employing him.

Cheers,

Paul.

"IMM" wrote in message ...
"Nick Brooks" wrote in message
...
John Rumm wrote:
Dave Baker wrote:

Indeed. I calculated that the maximum heat transfer through 1m of 8mm
pipe is 2.28Kw

About 2.5kW.

Not true. The pipe run is sized to suit. A decent length of 8mm pipe can
provide enough heat for a 2.5kW rad with flow/return temp differential of
11C. If running a condensing boiler on the system at 20C differential then
approx 4kW of heat will be delivered down a 8mm pipe.


Surely this all depends on pump pressure/flow and the pipe resistance
of the whole circuit, not just the 1m etc of microbore. No?

Regards, NT

"N. Thornton" wrote in message
om...
"IMM" wrote in message
...
"Nick Brooks" wrote in message
...
John Rumm wrote:
Dave Baker wrote:

Indeed. I calculated that the maximum heat transfer through 1m of 8mm
pipe is 2.28Kw

About 2.5kW.

Not true. The pipe run is sized to suit. A decent length of 8mm pipe
can
provide enough heat for a 2.5kW rad with flow/return temp differential
of
11C. If running a condensing boiler on the system at 20C differential
then
approx 4kW of heat will be delivered down a 8mm pipe.


Surely this all depends on pump pressure/flow and the pipe resistance
of the whole circuit, not just the 1m etc of microbore. No?

yep.

N. Thornton wrote:
"IMM" wrote in message ...

"Nick Brooks" wrote in message
...

John Rumm wrote:

Dave Baker wrote:


Indeed. I calculated that the maximum heat transfer through 1m of 8mm
pipe is 2.28Kw


About 2.5kW.


Not true. The pipe run is sized to suit. A decent length of 8mm pipe can
provide enough heat for a 2.5kW rad with flow/return temp differential of
11C. If running a condensing boiler on the system at 20C differential then
approx 4kW of heat will be delivered down a 8mm pipe.



Surely this all depends on pump pressure/flow and the pipe resistance
of the whole circuit, not just the 1m etc of microbore. No?

Regards, NT

Of course, I assumed a linear flow rate of 1.5m/s. and a temperature
difference of 10 degrees. The reason for using 1m of pipe in the
calculations is to give a maximum possible heat transfer. Other losses
in the system will reduce this.

Nick Brooks