The system currently in place has a Mexico boiler which is fairly old,
but from what I understand that unless it becomes uneconomical to
repair it's not cost (or environmentally) effective to replace it.

However, the radiators are extremely dated with many valves having
either leaked or are leaking. It's also a single pipe system and the
pipe work is not buried.

Therefore, is it a good idea to simply replace the radiators and pipe
work and leave the boiler until it packs up for good. If it is, does
the fact that it's a single pipe system make it more complicated/
impossible to replace it with a flow and return system.

The boiler is currently in the kitchen which is soon to be changed to
a dining room/study if that makes any difference, such as if a new
boiler would have to be sighted in a different room/position.

On 01/02/2010 22:20, geoffr wrote:
The system currently in place has a Mexico boiler which is fairly old,
but from what I understand that unless it becomes uneconomical to
repair it's not cost (or environmentally) effective to replace it.

However, the radiators are extremely dated with many valves having
either leaked or are leaking. It's also a single pipe system and the
pipe work is not buried.

If a knowledgeable responder could also give a single-sentence
definition of a single-pipe system I'd appreciate it (I mean, I can
guess, but would rather not).

Thx,

--
Tim

"That excessive bail ought not to be required, nor excessive fines
imposed, nor cruel and unusual punishments inflicted"

Bill of Rights 1689

On Mon, 01 Feb 2010 22:47:44 +0000, Tim Streater
wrote:

On 01/02/2010 22:20, geoffr wrote:
The system currently in place has a Mexico boiler which is fairly old,
but from what I understand that unless it becomes uneconomical to
repair it's not cost (or environmentally) effective to replace it.

However, the radiators are extremely dated with many valves having
either leaked or are leaking. It's also a single pipe system and the
pipe work is not buried.

If a knowledgeable responder could also give a single-sentence
definition of a single-pipe system I'd appreciate it (I mean, I can
guess, but would rather not).

Thx,

I think this'll explain it
http://diydata.com/planning/central_...ork.php#single

Usenet Nutter
wibbled on Monday 01 February 2010 22:54

On Mon, 01 Feb 2010 22:47:44 +0000, Tim Streater
wrote:

On 01/02/2010 22:20, geoffr wrote:
The system currently in place has a Mexico boiler which is fairly old,
but from what I understand that unless it becomes uneconomical to
repair it's not cost (or environmentally) effective to replace it.

However, the radiators are extremely dated with many valves having
either leaked or are leaking. It's also a single pipe system and the
pipe work is not buried.

If a knowledgeable responder could also give a single-sentence
definition of a single-pipe system I'd appreciate it (I mean, I can
guess, but would rather not).

Thx,

I think this'll explain it
http://diydata.com/planning/central_...ork.php#single

My first school had this system, and for that matter so did my last. 2" (I
think, might have been larger) iron loop pipe. Horrible system if you're on
the end (see above). Can't think why they did it - save pipe perhaps?

--
Tim Watts

Managers, politicians and environmentalists: Nature's carbon buffer.

On Feb 1, 4:20*pm, geoffr wrote:
The system currently in place has a Mexico boiler which is fairly old,
but from what I understand that unless it becomes uneconomical to
repair it's not cost (or environmentally) effective to replace it.

However, the radiators are extremely dated with many valves having
either leaked or are leaking. It's also a single pipe system and *the
pipe work is not buried.

Therefore, is it a good idea to simply replace the radiators and pipe
work and leave the boiler until it packs up for good. If it is, does
the fact that it's a single pipe system make it more complicated/
impossible to replace it with a flow and return system.

The boiler is currently in the kitchen which is soon to be changed to
a dining room/study if that makes any difference, such as if a new
boiler would have to be sighted in a different room/position.

I think your idea idea crazy, valves leak so fix or replace them, I
often can fix them. Go price your used radiators people sell. You
might have better than are sold now, mine are heavy cast iron by a
quality manufacturer about 90 yrs old and worth a good buck, better
made than new radiators now. Single pipe, one in one side, one out the
other, well thats fine as it always has been. Spend the money on a new
boiler and insulation and save on gas.

On Mon, 01 Feb 2010 14:20:51 -0800, geoffr wrote:

The system currently in place has a Mexico boiler which is fairly old,
but from what I understand that unless it becomes uneconomical to
repair it's not cost (or environmentally) effective to replace it.

However, the radiators are extremely dated with many valves having
either leaked or are leaking. It's also a single pipe system and the
pipe work is not buried.

The valves are relatively easily replaced. The pipework not so easily. You
don't have to replacing the pipework: single-pipe systems do work (though
they have disadvantages compared to twin-pipe).


Therefore, is it a good idea to simply replace the radiators and pipe
work and leave the boiler until it packs up for good. If it is, does
the fact that it's a single pipe system make it more complicated/
impossible to replace it with a flow and return system.

The boiler is currently in the kitchen which is soon to be changed to
a dining room/study if that makes any difference, such as if a new
boiler would have to be sighted in a different room/position.

If you're thinking Bigger Picture then not only would I consider replacing
the pipework, radiators and boiler but also going for underfloor heating
where possible and perhaps ground- or air- source heat pumps or a
wood-burner. I don't mean getting all religious about any of these
technologies: I mean /considering/ them, on their pros and cons.



--
John Stumbles -- http://yaph.co.uk

Life is nature's way of keeping meat fresh

In article ,
Usenet Nutter writes:
On Mon, 01 Feb 2010 22:47:44 +0000, Tim Streater
wrote:

On 01/02/2010 22:20, geoffr wrote:
The system currently in place has a Mexico boiler which is fairly old,
but from what I understand that unless it becomes uneconomical to
repair it's not cost (or environmentally) effective to replace it.

However, the radiators are extremely dated with many valves having
either leaked or are leaking. It's also a single pipe system and the
pipe work is not buried.

If a knowledgeable responder could also give a single-sentence
definition of a single-pipe system I'd appreciate it (I mean, I can
guess, but would rather not).

Thx,

I think this'll explain it
http://diydata.com/planning/central_...ork.php#single

A number of issues about that description...

The diagram shows the inlet at the top of the radiators. This
is neither necessary nor the norm IME - usually both pipes are
connected to the bottom of the radiators. My suspicion is that
the diagram has been modifed from a gravity feed diagram.
I have seen it done in rows of conceiled radiators, but that
was so the on/off valve could be accessed at the top of the
casing.

Whilst radiators on a single pipe circuit will sometimes have
a valve for manual on/off, they don't have a valve for
balancing flow.

The flow balancing is done using a single gate valve for
each circuit. An installation would typically have 3 or more
circuits, and these are balanced against each other, not by
balancing individual radiators.

The comment about radiators at the end being colder is misleading.
Yes they are colder, but that's taken into account in the system
design. If you need equal power output from the radiators, they
start off smaller and get larger further along the run. If they're
all in one room, another way to do this is to space the initial
ones further apart and the final ones closer together. A more
common approach was to use unequal heat loss along a room to
counteract it, so in a long office area, there might be more heat
loss at the end-wall end than in the middle of the building, so
the initial radiators were placed at the end-wall end.

Calculating radiator sizes with single pipe systems had to be
done much more accurately than is now normally done, but in
those days systems were designed by real heating engineers, so
that was the norm anyway. It's probably going to be hard today
to find heating installers who actually understand how such
systems were designed, hence the derision by those who mostly
don't understand them. It's not sensible to install such a
system today, but comments about inefficiency (such as in that
article) are mainly borne out of ignorance.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Tue, 2 Feb 2010 10:17:44 +0000 (UTC),
(Andrew Gabriel) wrote:

The comment about radiators at the end being colder is misleading.
Yes they are colder, but that's taken into account in the system
design. If you need equal power output from the radiators, they
start off smaller and get larger further along the run. If they're
all in one room, another way to do this is to space the initial
ones further apart and the final ones closer together. A more
common approach was to use unequal heat loss along a room to
counteract it, so in a long office area, there might be more heat
loss at the end-wall end than in the middle of the building, so
the initial radiators were placed at the end-wall end.


Doing what is said above ...small rads to start with getting larger
and spacing them as described is unlikely to be practical in a
domestic situation tho' is it ?

In article ,
Usenet Nutter writes:
On Tue, 2 Feb 2010 10:17:44 +0000 (UTC),
(Andrew Gabriel) wrote:

The comment about radiators at the end being colder is misleading.
Yes they are colder, but that's taken into account in the system
design. If you need equal power output from the radiators, they
start off smaller and get larger further along the run. If they're
all in one room, another way to do this is to space the initial
ones further apart and the final ones closer together. A more
common approach was to use unequal heat loss along a room to
counteract it, so in a long office area, there might be more heat
loss at the end-wall end than in the middle of the building, so
the initial radiators were placed at the end-wall end.

Doing what is said above ...small rads to start with getting larger
and spacing them as described is unlikely to be practical in a
domestic situation tho' is it ?

If you mean todays installers wouldn't have a clue how to work
out the size or spacing, then I would agree, but changes in
heating system designs have made that unnecessary, bringing down
the skill level and costs involved in installation - an engineer
isn't any longer required. However, the engineers who designed
single pipe systems 50 years ago did exactly that.

Domestic situations don't tend to have 100' long rooms to heat
with radiators running down the sides. You have one or two
radiators in each room, and the power requirements to the rooms
are likely to be different so you need different sized radiators
anyway. Therefore it may not be obvious that the ones at the
start of the circuit were sized relatively smaller than the
ones at the end, verses what would have been done for a two
pipe design, but that is exactly what was done.

Probably the most significant issue in converting a single pipe
system to a condensing boiler is that the radiators won't have
been oversized at all for the original system. In later installs,
particularly with TRV's, radiators were usually oversized rather
than actually perform the calcs to work out how big they needed
to be, and this becomes a real advantage with a condensing boiler.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 2 Feb, 10:17, (Andrew Gabriel) wrote:
In article ,
* * * * Usenet Nutter writes:



On Mon, 01 Feb 2010 22:47:44 +0000, Tim Streater
wrote:

On 01/02/2010 22:20, geoffr wrote:
The system currently in place has a Mexico boiler which is fairly old,
but from what I understand that unless it becomes uneconomical to
repair it's not cost (or environmentally) effective to replace it.

However, the radiators are extremely dated with many valves having
either leaked or are leaking. It's also a single pipe system and *the
pipe work is not buried.

If a knowledgeable responder could also give a single-sentence
definition of a single-pipe system I'd appreciate it (I mean, I can
guess, but would rather not).

Thx,

I think this'll explain it
http://diydata.com/planning/central_...ork.php#single

A number of issues about that description...

The diagram shows the inlet at the top of the radiators. This
is neither necessary nor the norm IME - usually both pipes are
connected to the bottom of the radiators. My suspicion is that
the diagram has been modifed from a gravity feed diagram.
I have seen it done in rows of conceiled radiators, but that
was so the on/off valve could be accessed at the top of the
casing.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

You are right about the pipes being connected at the bottom -at least
on our system.

I have also read that its very hard to get rid of air locks in single
pipe systems and if that is correct I'm wary about draining down the
system to change a load of valves and then spending ages trying to
remove air locks. Although having said that it's obviously easier then
replacing the pipes and radiators!

The reason I'm thinking off changing the pipework is that the property
is in the process of being redecorated and therefore it would be an
ideal time to renew them and the radiators. Out of interest the
pipework in the house is mainly stainless steel which I have
discovered is a lot harder to cut than copper.

The house is about 45 years old and I assume the pipework and rads
must be the originals and perhaps they will need replacing soon
anyway. It's is just that I dont want to replace a boiler that while
old is working perfectly.

Andrew Gabriel wrote:

The diagram shows the inlet at the top of the radiators. This
is neither necessary nor the norm IME - usually both pipes are
connected to the bottom of the radiators. My suspicion is that
the diagram has been modifed from a gravity feed diagram.
I have seen it done in rows of conceiled radiators, but that
was so the on/off valve could be accessed at the top of the
casing.


My school had a single-pipe system pretty much exactly like the diagram.
Big cast iron rads and 2 inch steel pipes. Solid and boy-proof.

Given when I went there and it being a part-Tudor building it could
easily have been installed 50 years ago, when as you say they had proper
engineers.

Andy