Anybody got any experience of installing / operating this kind of heating.
It's a 2 storey cottage and I'm considering installing 2 circuits (one
upstairs and one downstairs) using a single 15mm pipe in one radiator and
out the next.
One of the reasons for this is that the walls are 2.5 feet thick.
It will be fed from an eternal oil fired combi boiler.

In article ,
"Frank McGuire" writes:
Anybody got any experience of installing / operating this kind of heating.
It's a 2 storey cottage and I'm considering installing 2 circuits (one
upstairs and one downstairs) using a single 15mm pipe in one radiator and
out the next.

That's not quite what a single pipe system is. Start by imagining
a large loop of pipe with no radiators on it. Now you tap them in
to the loop, but without breaking the loop. If you look at it like
an electrical circuit, each radiator would seem to be shorted out
by the loop, but that analogy is wrong as the radiator can be
looked upon as a much thicker pipe which will therefore take the
majority of the flow unless restricted by the valves.

Selection of radiator sizes is much more critical than with a
parallel pipe system. Balancing is then done per loop, not per
radiator. You should take into account the falling average rad
temperature around the loop when sizing radiators.

One of the reasons for this is that the walls are 2.5 feet thick.
It will be fed from an eternal oil fired combi boiler.

I think you might struggle to find plumbers nowadays who understand
single pipe systems, at least in enough detail to design one.

--
Andrew Gabriel

Andrew Gabriel wrote:
In article ,
"Frank McGuire" writes:
Anybody got any experience of installing / operating this kind of heating.
It's a 2 storey cottage and I'm considering installing 2 circuits (one
upstairs and one downstairs) using a single 15mm pipe in one radiator and
out the next.

That's not quite what a single pipe system is. Start by imagining
a large loop of pipe with no radiators on it. Now you tap them in
to the loop, but without breaking the loop. If you look at it like
an electrical circuit, each radiator would seem to be shorted out
by the loop, but that analogy is wrong as the radiator can be
looked upon as a much thicker pipe which will therefore take the
majority of the flow unless restricted by the valves.

Selection of radiator sizes is much more critical than with a
parallel pipe system. Balancing is then done per loop, not per
radiator. You should take into account the falling average rad
temperature around the loop when sizing radiators.

One of the reasons for this is that the walls are 2.5 feet thick.
It will be fed from an eternal oil fired combi boiler.

I think you might struggle to find plumbers nowadays who understand
single pipe systems, at least in enough detail to design one.

--
Andrew Gabriel

I thought the reason the radiators heat up is gravity feed, i.e. the
cold water 'falls' into the pipe after the radiator and 'rises' into it
at the beginning by virtue of the differing density. This would fit in
with my experience (I have a one pipe system which I'm planning to be
rid of) where the pipework all gets hot well before the radiators do.
It's not a great system as Andrew said as there is a temp drop around
the circuit.

To be honest there's not much more work involved in making a hole big
enough for a pair of pipes compared to a single (again I have some
experience as my walls are 2' thick so you're only ahead by 6"). It
will then be easier to balance, more efficient/effective and any
plumber who comes in subsequently will be able to work out what to do.
I had real problems with mine when I had to change some rads due to
them rusting through, ended up having to sort it myself.

Incidentally could you point us all in the direction of your boiler
supplier, I would rather nbot have oil but the idea of having an
"eternal boiler" strikes me as a good one!

Fash

There are two single pipe systems - one where the radiator sits on top of
the pipe and would be connected via T pieces, and the other where the
radiator is in series with the pipe and would be connected using elbows.
It's the latter that I'm interested in.

"Fash" wrote in message
ups.com...

Andrew Gabriel wrote:
In article ,
"Frank McGuire" writes:
Anybody got any experience of installing / operating this kind of
heating.
It's a 2 storey cottage and I'm considering installing 2 circuits (one
upstairs and one downstairs) using a single 15mm pipe in one radiator
and
out the next.

That's not quite what a single pipe system is. Start by imagining
a large loop of pipe with no radiators on it. Now you tap them in
to the loop, but without breaking the loop. If you look at it like
an electrical circuit, each radiator would seem to be shorted out
by the loop, but that analogy is wrong as the radiator can be
looked upon as a much thicker pipe which will therefore take the
majority of the flow unless restricted by the valves.

Selection of radiator sizes is much more critical than with a
parallel pipe system. Balancing is then done per loop, not per
radiator. You should take into account the falling average rad
temperature around the loop when sizing radiators.

One of the reasons for this is that the walls are 2.5 feet thick.
It will be fed from an eternal oil fired combi boiler.

I think you might struggle to find plumbers nowadays who understand
single pipe systems, at least in enough detail to design one.

--
Andrew Gabriel

I thought the reason the radiators heat up is gravity feed, i.e. the
cold water 'falls' into the pipe after the radiator and 'rises' into it
at the beginning by virtue of the differing density. This would fit in
with my experience (I have a one pipe system which I'm planning to be
rid of) where the pipework all gets hot well before the radiators do.
It's not a great system as Andrew said as there is a temp drop around
the circuit.

To be honest there's not much more work involved in making a hole big
enough for a pair of pipes compared to a single (again I have some
experience as my walls are 2' thick so you're only ahead by 6"). It
will then be easier to balance, more efficient/effective and any
plumber who comes in subsequently will be able to work out what to do.
I had real problems with mine when I had to change some rads due to
them rusting through, ended up having to sort it myself.

Incidentally could you point us all in the direction of your boiler
supplier, I would rather nbot have oil but the idea of having an
"eternal boiler" strikes me as a good one!

Fash

In article ,
"Frank McGuire" writes:
There are two single pipe systems - one where the radiator sits on top of
the pipe and would be connected via T pieces, and the other where the
radiator is in series with the pipe and would be connected using elbows.
It's the latter that I'm interested in.

Never seen or heard of this.
You couldn't turn a radiator off, for one.

--
Andrew Gabriel

In article ,
Frank McGuire wrote:
Anybody got any experience of installing / operating this kind of
heating. It's a 2 storey cottage and I'm considering installing 2
circuits (one upstairs and one downstairs) using a single 15mm pipe in
one radiator and out the next. One of the reasons for this is that the
walls are 2.5 feet thick. It will be fed from an eternal oil fired combi
boiler.

You've got internal walls 2.5ft thick in a cottage?

Even then I can't really see what saving you'd have since a one pipe
system still has two pipes - it's just how those are tapped off to the
rads which is different.

--
*I don't have a solution, but I admire your problem. *

Dave Plowman London SW
To e-mail, change noise into sound.

"Andrew Gabriel" wrote in message
...
In article ,
"Frank McGuire" writes:
There are two single pipe systems - one where the radiator sits on top of
the pipe and would be connected via T pieces, and the other where the
radiator is in series with the pipe and would be connected using elbows.
It's the latter that I'm interested in.

Never seen or heard of this.
You couldn't turn a radiator off, for one.

--
Andrew Gabriel

Both were common in the '50s and '60's. The series type was often seen in
public buildings and schools - with cast iron pipes.

The later was often retro fitted in the '60's as a package. A house I work
on has this. It isn't great - but not worth changing. Must have been
installed in the Wimpy house in the mid-60's.

In article ,
John wrote:
Both were common in the '50s and '60's. The series type was often seen
in public buildings and schools - with cast iron pipes.

Long time ago I had a rented flat - part of a large house - with a
communal heating system like that. Gravity circulation and the boiler was
a non electric type - complete with clockwork timeswitch. The pipework was
a work of art with beautiful welds in places. It was only designed for
background heating of 55F on a cold day - and worked very well. Installed
in the early '50s, IIRC.

--
*If one synchronized swimmer drowns, do the rest have to drown too?

Dave Plowman London SW
To e-mail, change noise into sound.