OK, I am so fed up with different plumbers and all their different
opinions. Can any of you help?

I have a very simple question and I hope its a straight forward
answer. I will miss out on the problem and suggested solutions and
hope this can be answered without the details.

Q Would you be happy keeping 8mm microbore thoughout your house (with
flow problems) or would you upgrade all to 15mm?

I realise that you may want more details but I'm not gonna give them.
This is the most basic difference 3 plumbers have told me.

No. 1 wants to change all pipes to 15mm
No. 2 wants to change only the 6mm pipe to 15mm
No. 3 wants to keep the 8mm

Please help. Its doing my head in!

Many thanks
Rebecca

On 18 Aug 2003 00:19:23 -0700, (Rebecca) wrote:

OK, I am so fed up with different plumbers and all their different
opinions. Can any of you help?

I have a very simple question and I hope its a straight forward
answer. I will miss out on the problem and suggested solutions and
hope this can be answered without the details.

Q Would you be happy keeping 8mm microbore thoughout your house (with
flow problems) or would you upgrade all to 15mm?

I realise that you may want more details but I'm not gonna give them.
This is the most basic difference 3 plumbers have told me.

No. 1 wants to change all pipes to 15mm
No. 2 wants to change only the 6mm pipe to 15mm
No. 3 wants to keep the 8mm

Please help. Its doing my head in!

Many thanks
Rebecca

I have 8mm pipe throughout my house, Rebecca, and there would be no
need to change it.



The question can't be comprehensively answered without some level of
background, and some detail of explanation is needed to make the right
decision but I'll give you the following::

- Systems using microbore are not any different in principle to any
other. The typical implementation difference is that systems using
22mm and then 15mm tube to radiators are connected like a tree with
the 22mm forming the trunk and the 15mm the branches. In microbore
installations it is typical to have one or more manifolds which are
distribution points attached to the 22mm pipes and then 8mm (or
sometimes 6mm or 10mm) are run from those to the radiators. In effect
you might connect our or more radiators to a single point. There is
no reason that manifolds have to be used, however - a microbore system
could be designed like a tree.

- In any system, the amount of heat that can be delivered from a
radiator is determined by its size and the room temperature (plus some
other factors), but assumes that a certain flow rate of water is going
through. The larger and higher output a radiator is, the more water
flow is required. Tube of any kind has a restricting effect on the
flow of water. The longer the length, and the smaller the diameter,
the greater the restriction. To some extent, the pump makes up for
this, but there is a limit and a properly designed system should have
the flow speeds through all pipes under 1.5m/sec. Think of it like a
stream which flows quickly and a river, with greater dimensions
flowing more slowly.

- You can relate the pipe diameters as a result, to the amount of
heat. In a proper design, the heating engineer will have worked out
the pipe sizes based on the amount of heat required to be delivered
through them - there are tables to do this. However, as a rule of
thumb, 15mm tube in an average house can carry up to 6kW of heat and
8mm up to about 2.5kW. 6mm is about 1.5kW. These numbers are
reduced if the lengths are overly great. In the case of microbore
and radiators connected to a manifold, each can be considered
separately and you can work out immediately whether pipework is
adequate. In the case of 15mm connected as a tree with more than one
radiator on a run of it, you add the requirements of the radiators.

- You can work out radiator heat outputs by measuring them and looking
up the manufacturer's data sheets. The nominal output in the tables,
which comes from a European measuring standard needs to be scaled
downwards by multiplying by 0.9 for most UK heating systems.

- In a practical case where you already have a system, it may be
working perfectly well. If it isn't, the usual problem is that one
or more radiators are not getting hot enough or at all.
There can be three causes of this:-

a) The system wasn't designed properly and there are one or more
radiators that are too large for the size of pipe. The only fix for
this is to put in larger pipes or to reduce the radiator size, perhaps
adding a second radiator connected back to a manifold.

b) The system isn't properly balanced. This procedure involves
adjusting the lockshield valves on the radiators (these are the ones
at the opposite end to the ones you turn) so that the flow of water
through each radiator is adjusted to what is required by it. Doing
this properly is time consuming and requires a thermometer to measure
the temperature at each end of a radiator. You then go round the
house adjusting a little at a time until the correct temperature drop
of 12 degrees C is measured at each radiator. The problem is that
adjusting each affects the others so this can take a very long time.
Hence CH installers often take a short cut and just adjust the hottest
radiators down until the coolest ones warm up.

c) The system has become silted. This happens from the corrosion of
steel radiators and produces a brown-black sludge. In a microbore
system, this can tend to reduce the flow through the pipework more
quickly than 15mm because some is carried from the radiators into the
pipes. The smaller size of microbore will obviously silt up more
quickly. However, the problem is entirely curable by flushing the
system with clean water. In a badly silted system, it's helpful to
take the radiators off and flush them outside. This does require care
to avoid silted water, which is a great brown dye from dripping on the
carpets. Another favourite game of plumbers is power flushing to do
this task. They connect up a powerful pump and some cleaning
chemical to do it and charge several hundred pounds. This is a rip
off considering what is involved.
The whole situation of silting is very easily preventable by the
addition of corrosion inhibitor (about £20 every three years) to the
system. I've done this in my system (18 years old) since new and it
has remained virtually pristine.


I can see no reason at all to change everything to 15mm unless the
system was so badly designed that all the radiators are inadequately
connected. I think that plumber (1) is just looking to expand the
work and the the price. It wouldn't be British Gas would it?

There may be some merit in changing 6mm pipes if the radiators using
them are not warming up, provided that balancing and silting have been
eliminated.

If everything is properly designed, clean and balanced there should be
no reason to change from 8mm.


..andy

To email, substitute .nospam with .gl

"Rebecca" wrote in message
om...
OK, I am so fed up with different plumbers and all their different
opinions. Can any of you help?

I have a very simple question and I hope its a straight forward
answer. I will miss out on the problem and suggested solutions and
hope this can be answered without the details.

Q Would you be happy keeping 8mm microbore thoughout your house (with
flow problems) or would you upgrade all to 15mm?

I realise that you may want more details but I'm not gonna give them.
This is the most basic difference 3 plumbers have told me.

No. 1 wants to change all pipes to 15mm
No. 2 wants to change only the 6mm pipe to 15mm
No. 3 wants to keep the 8mm

Please help. Its doing my head in!

Many thanks
Rebecca

I live an old house (17th C.) so installed microbore over 25 years ago. I've
had no problems in all that time. I think it was 8mm and am not familiar
with 6mm.

If it aint broke don't mess with it!

Very useful information Andy. Thanks.

I wonder if a bit more info will narrow it down then...

Our house has a mixture of new and old steel rads. The new ones are
fine (not as hot as they could be but they heat up more or less
evenly), but the steel rads are heating very badly (only the top 2
inches)- despite us removing them last year and cleaning them
thoroughly (and cleaning the system with Fernox etc).

So, we were recommended to buy new rads to replace these old ones,
which we have done - I must admit the plumber who told us the sizes to
buy did guestimate. Looking at the B&G catalogue, the output of these
4 new rads ranges from 4500 to 6200. 3 of them are currently on 8mm,
and the smallest is on 6mm.

From your figures Andy if the general rule of thumb applies, it looks
like we will have to replace most of the pipes (as 8mm generally deals
with up to 4500w). Have I interpreted this correct?

The plumber that recommended changing all the pipes to 15mm (but did
not recommend changing the rads) was the only one which was
recommended to us.

Your opinion with this extra bit of info would be much appreciated!

Changing tac slightly 0 another plumber told us that we would have to
change the pipes coming form the boiler (some sort of Potterton) from
22mm to 28mm and that is why the circulation is bad. This sounds dodgy
to me...we had about 6 plumbers round and no-one mentioned this. What
do you think?

Thanks
Rebecca


(Rebecca) wrote in message . com...
OK, I am so fed up with different plumbers and all their different
opinions. Can any of you help?

I have a very simple question and I hope its a straight forward
answer. I will miss out on the problem and suggested solutions and
hope this can be answered without the details.

Q Would you be happy keeping 8mm microbore thoughout your house (with
flow problems) or would you upgrade all to 15mm?

I realise that you may want more details but I'm not gonna give them.
This is the most basic difference 3 plumbers have told me.

No. 1 wants to change all pipes to 15mm
No. 2 wants to change only the 6mm pipe to 15mm
No. 3 wants to keep the 8mm

Please help. Its doing my head in!

Many thanks
Rebecca

"Rebecca" wrote in message
om...
Very useful information Andy. Thanks.

I wonder if a bit more info will narrow it down then...

Our house has a mixture of new and old steel rads. The new ones are
fine (not as hot as they could be but they heat up more or less
evenly), but the steel rads are heating very badly (only the top 2
inches)- despite us removing them last year and cleaning them
thoroughly (and cleaning the system with Fernox etc).

So, we were recommended to buy new rads to replace these old ones,
which we have done - I must admit the plumber who told us the sizes to
buy did guestimate. Looking at the B&G catalogue, the output of these
4 new rads ranges from 4500 to 6200. 3 of them are currently on 8mm,
and the smallest is on 6mm.

From your figures Andy if the general rule of thumb applies, it looks
like we will have to replace most of the pipes (as 8mm generally deals
with up to 4500w). Have I interpreted this correct?

The plumber that recommended changing all the pipes to 15mm (but did
not recommend changing the rads) was the only one which was
recommended to us.

Your opinion with this extra bit of info would be much appreciated!

Changing tac slightly 0 another plumber told us that we would have to
change the pipes coming form the boiler (some sort of Potterton) from
22mm to 28mm and that is why the circulation is bad. This sounds dodgy
to me...we had about 6 plumbers round and no-one mentioned this. What
do you think?

Have you added rads, or have you just replaced defective rads. If just
replacing then did the system operate fine previously. If it did work fine
then you have blockage of some sort.



---
--

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.507 / Virus Database: 304 - Release Date: 05/08/2003

Hi Andt,

To answer your queries:

1. The rads I mention are not as old as the antique types you mention
so I guess I mean old versions of more modern panel types.

2. I thought it was the typical triangle shape heat distribution but
it also sounds a bit like the top only and either end of rad heating
you suggested (I get the impression I am, not beong clear!)- when we
cleaned one out last year, it worked perfectly for a couple of weeks
before going back to the orignal useless heat distribution.

3. Yes, the new rads are in BTU/hr so I guess the existing pipes
should be ok. Phew.

I think we'll get a bloke round to change the rads and see how we get
on then. Fingers crossed it will be fine!

Thanks for the tips. You don't live near J9 of the M25 by any chance
do you? You sound like a very useful man to know!

Will keep you updated
Rebecca

Andy Hall wrote in message . ..
On 19 Aug 2003 11:06:53 -0700, (Rebecca) wrote:

Very useful information Andy. Thanks.

I wonder if a bit more info will narrow it down then...

Our house has a mixture of new and old steel rads. The new ones are
fine (not as hot as they could be but they heat up more or less
evenly), but the steel rads are heating very badly (only the top 2
inches)- despite us removing them last year and cleaning them
thoroughly (and cleaning the system with Fernox etc).

Sorry, Rebecca, just to be clear, when you talk about "old" rads, do
you mean the almost antique column types as in

http://www.tuscanfoundry.co.uk/subcategories.asp?cat=61

for example - i.e. the old cast iron types, or do you mean old
versions of more modern panel types?

Working out the expected heat output of the old cast iron types is
guesswork to some extent, but you could use the site I've mentioned
above and do a reasonable estimate based on sizes and design.

If they are the steel panel type but an older design, then try to find
something similar on the web sites of manufacturers like Myson,
Stelrad or Barlo.

You will sometimes notice that outputs are quoted per section for a
given type. All you then do is to take the number of sections for
your given radiator and multiply.

You will also notice that the output depends on the radiator type and
that with panel radiators you can have single or double panels and 0,1
or 2 sets of fins. These increase the output by increasing the
surface area that's hot.

If youu were saying that only the tops of the radiators in question
were hot but actually the cold area was more of a triangular shape at
the bottom, then this is normally an indication that there is sludge
in the bottom of the radiator. However if the hot area is at the top
and perhaps vertically at the end where the hot water enters, then it
is almost certainly inadequate flow for the radiator size.

That can be because the pipes are inadequate or partly blocked or the
system is way out of balance or that the pump is on too low a setting.

The situation can be exacerbated if you have some large radiators
relatively close to the boiler on the heating connections which are
connected with 15mm pipe and others further away on 8mm. Since the
flow will take the line of least resistance, the lockshield valves on
the 15mm connected radiators would typically need to be turned down a
fair way and those on 8mm connected radiators relatively open.

One thing you could do as a sanity check is to close the normal
control valves (or thermostatic valves) on all the radiators that are
getting hot and see whether the cold radiators improve substantially.
You could even close all but one. If there is a dramatic
improvement, you have a balance problem, otherwise it's pipes too
small, partial blocking or pump setting too low. You can easily
test pump setting by changing it and checking the effect - again with
the hotter radiators turned off.

Even if you did clean the radiators and put in Fernox, you could have
a partial block of pipes. This would involve flushing the system at
the radiator connections to check and clear for certain.


So, we were recommended to buy new rads to replace these old ones,
which we have done - I must admit the plumber who told us the sizes to
buy did guestimate. Looking at the B&G catalogue, the output of these
4 new rads ranges from 4500 to 6200. 3 of them are currently on 8mm,
and the smallest is on 6mm.

Do you mean 4500 to 6200 Watts here, Rebecca, or BTUs/hr?

One thing that irritates me about the heating industry is that they
persist in keeping the old BTU units; but the greater sin is that you
often see them mixed in specifications and designs. This is a recipe
for trouble because it's easy to make a numerical slip.

The conversion factor is 3412 BTUs/hr = 1kW.

So are the sizes you have bought really 4500W to 6200W or those
numbers in BTUs/hr? Manufacturer's data sheets normally have both.

These are pretty big radiators if they are in Watts and 8mm and
definitely 6mm would be woefully inadequate. If the numbers are in
BTUs/hr you are talking about 1.3kW and 1.8kW, which should be within
the range of 6mm and 8mm respectively as long as the pipes are no
longer than about 3-4 metres. Above these lengths, a proper
calculation of flow resistance ought to be done using tables for the
tube sizes. If you have that situation (e.g. if it's 10m or
something) then I can point you to the information.





From your figures Andy if the general rule of thumb applies, it looks
like we will have to replace most of the pipes (as 8mm generally deals
with up to 4500w). Have I interpreted this correct?

2500W for 8mm I think I said.


The plumber that recommended changing all the pipes to 15mm (but did
not recommend changing the rads) was the only one which was
recommended to us.

I think before you go to that trouble, there are some checks to do.

- First of all whether you can make a significant difference by
checking the system balance as described above - i.e. with turning off
radiators and playing with the pump speed.

-Even when the radiator is reasonably hot and several are working it's
worth checking the balance. You need a contact thermometer to do
this. The cheapest suitable form of these are boiler thermometers
which are a round dial type with a pointer and are held in place on
the pipe with a spring. B&Q and plumbers or heating merchants have
them for about £10. For doing a proper balancing adjustment
exercise, two are helpful but one will do to start with.
With the system running, measure the temperature of the flow pipe from
the boiler and then measure the return. You will probably find that
these rise as the boiler is firing and fall when its internal
thermostat turns off the burner. I would suggest taking the peak
values in this case. Then check the temperatures at each ends of
radiators. If any have a much higher return temperature than the
return at the boiler, you will know that the flow rate is
unnecessarily high through them. On the other hand, any that have a
lower return temperature, may not be receiving enough flow. If it's
way out, and you can bear your hand on the return pipes of the cooler
radiators then you know the flow is inadequate, but for temperatures
of more than about 55 degrees, you can't bear your hand on the surface
and it's not so easy to tell.

- To some extent, you can push more water through the smaller pipes by
increasing the pump setting. If this is effective, the affected
radiators will become warmer, as will their return pipes. However if
the pump becomes a lot noisier and you can hear the sound of water
movement more clearly at the affected radiators, it's a fair
indication that the pipes are inadequate or partly blocked. This is
why pipes are rated assuming a flow rate below 1.5metres/sec - to
avoid noise and turbulence in the pipes.

- If, let's say, you are able to fix the problem by checking balancing
(and you might), then there is a proper procedure in the group FAQ
(Phil Addison looks after this and posts a URL) on how to balance
properly.


There is still a big "however" though. You could completely cure
the warming of the radiators and the room(s) could still be
inadequately heated. I raise the point, because your older
radiators were of unknown output and one plumber has made a size
guesstimate.

You could run into a situation where the radiator output is simply not
enough for the room - the point is that radiators compensate for the
heat loss through the surfaces and due to air changes.

If you get to the point that it's pretty clear that new pipework is
needed, before you splash out on that, I would also check whether the
radiators are going to be big enough when they are working properly.
Unfortunately, some plumbers work by rule of thumb on this as well and
measure the volume of the house and divide by their auntie's telephone
number :-)

It is fairly easy to work out the heat requirement for a room using
software that you can download from the radiator manufacturer's web
sites (Barlo and Myson have good ones). Basically you have to
measure the walls, ceiling and floor and windows, and enter them into
the program while selecting what type of material they are. You also
put in the inside required temperature (e.g. 21 degrees for a living
room) and the outside (say worst case -3) and the likely number of air
changes per hour. You will get heat loss numbers for the room.
Basically, for a surface, the amount of heat loss through it depends
on the area, the temperature difference and a factor for the type of
material - you multiply these together for each surface and then add
the lot - the software does it for you.

It should be possible to do this exercise for a complete house in an
evening and could save some expensive mistakes of wrongly sizing
radiators. If you want to do this exercise, I've posted on it
before quite a bit.








Your opinion with this extra bit of info would be much appreciated!

Changing tac slightly 0 another plumber told us that we would have to
change the pipes coming form the boiler (some sort of Potterton) from
22mm to 28mm and that is why the circulation is bad. This sounds dodgy
to me...we had about 6 plumbers round and no-one mentioned this. What
do you think?


This is entirely possible, and is the opposite end of the same issue
that you might have with the radiators.

The boiler has a certain heat output, or normally a range of heat
outputs. In the same way that there must be adequate flow through a
radiator to achieve its specifiied output, there must be enough flow
through a boiler to get the heat away from it.

The results of inadequate pipe size are less immediately obvious,
though. If the problem is not too bad, all that will happen is that
the boiler's internal thermostat will shut the burner off for more of
the time during a heating cycle (room thermostat is demanding heat),
leaving the pump running. In more extreme cases, the boiler "short
cycles" which means that the burner might light for one minute and off
for two minutes etc. Basically this is because the burner is able to
deliver heat at a far greater rate than the water flow can take it
away.

Inadequate flow here can be because of inadequate pipe size at the
boiler, inadequate pump speed or because the flow through the
radiators is too low as a result of too many having inadequate pipe
sizes or part blocking or lockshield valves turned down too much.

To determine what the pipe size should be, it's necessary to know the
boiler output. Can you find the exact model number and ideally the
output rating in kW or BTU/hr? There are databases and
specifications around if you can only find the model number.

22mm tends to be the more common used for boilers in small to medium
sized older properties and small to relatively large newer properties.
If it's an older property and/or is fairly large (i.e. greater heat
loss) then 28mm might be needed.

Often though, the pipe runs immediately from the boiler are relatively
short before splitting for upstairs and downstairs connections, so
even if they are a bit undersized, it won't necessarily be the overall
limiting factor.

This is one to keep in mind, but I would check everything else first,
especially if some of the radiators are working properly.





Thanks
Rebecca


(Rebecca) wrote in message . com...
OK, I am so fed up with different plumbers and all their different
opinions. Can any of you help?

I have a very simple question and I hope its a straight forward
answer. I will miss out on the problem and suggested solutions and
hope this can be answered without the details.

Q Would you be happy keeping 8mm microbore thoughout your house (with
flow problems) or would you upgrade all to 15mm?

I realise that you may want more details but I'm not gonna give them.
This is the most basic difference 3 plumbers have told me.

No. 1 wants to change all pipes to 15mm
No. 2 wants to change only the 6mm pipe to 15mm
No. 3 wants to keep the 8mm

Please help. Its doing my head in!

Many thanks
Rebecca

.andy

To email, substitute .nospam with .gl

On 20 Aug 2003 10:41:40 -0700, (Rebecca) wrote:

Hi Andt,

To answer your queries:

1. The rads I mention are not as old as the antique types you mention
so I guess I mean old versions of more modern panel types.

2. I thought it was the typical triangle shape heat distribution but
it also sounds a bit like the top only and either end of rad heating
you suggested (I get the impression I am, not beong clear!)- when we
cleaned one out last year, it worked perfectly for a couple of weeks
before going back to the orignal useless heat distribution.

Hmm. Then I think that considering you have had Fernox in the system
it is not likely to be corrosion of the radiators themeselves, at
least certainly not in that timescale.

Silt and crud somewhere being carried into the microbore pipes from
another radiator or pipework that does have some sludge is plausible
if the system went bad after a while - especially if the 6mm is worse
or became worse more quickly than the 8mm.

Do you have thermostatic valves or was anything else changed?



3. Yes, the new rads are in BTU/hr so I guess the existing pipes
should be ok. Phew.

I think we'll get a bloke round to change the rads and see how we get
on then. Fingers crossed it will be fine!

Hopefully, although I am not sure.

You could usefully ask him to flush the system at each radiator valve
(both ends) as he goes to see if it brings out any grot from the
system pipework.

If there is, then it would be worth going to each radiator - even
those which are apparently OK. Take them off and outside and flush
them through with a mains water hose or a pressure washer if you have
it. Flush from each radiator valve as you go to carry any silt in the
pipework out. Unfortunately just flushing to a drain cock in one
place doesn't really achieve this well.

This sounds like a bit of a pain, but you can actually do a whole
house worth of radiators in a couple of hours. Do note the settings
of each lockshield valve if you close it at all. Having said that, I
have a feeling that a balancing exercise is going to be on the list as
well.

Also another reminder - do watch for the sludge and even rusty water
drips. The compounds are one of the most indellible dyes known to
man :-( One useful trick if you are taking radiators outside is to
put a small plastic sandwich bag over each tail after you have undone
the nut and attach with a rubber band. Then you won't get drips on
the floor. I also found that new cat litter trays from the
supermarket are a cheap and useful container to put under the valves
as you undo them and even to flush.


Thanks for the tips. You don't live near J9 of the M25 by any chance
do you? You sound like a very useful man to know!

My "world of adventures" is nearer to J10 of the M4 :-)



Will keep you updated

Please do - this is a bit of a puzzle.



Rebecca


..andy

To email, substitute .nospam with .gl

"Rebecca" wrote in message
om...
Hi Andt,

To answer your queries:

1. The rads I mention are not as old as the antique types you mention
so I guess I mean old versions of more modern panel types.

2. I thought it was the typical triangle shape heat distribution but
it also sounds a bit like the top only and either end of rad heating
you suggested (I get the impression I am, not beong clear!)- when we
cleaned one out last year, it worked perfectly for a couple of weeks
before going back to the orignal useless heat distribution.

3. Yes, the new rads are in BTU/hr so I guess the existing pipes
should be ok. Phew.

I think we'll get a bloke round to change the rads and see how we get
on then. Fingers crossed it will be fine!

And get a powerflush on "all" pipes. Then run the system on 80C all the
time. If you are getting new rads get low surface temperature rads as these
can be safely run at 80C.





---
--

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.507 / Virus Database: 304 - Release Date: 04/08/2003

On Wed, 20 Aug 2003 20:53:50 +0100, "IMM" wrote:


"Rebecca" wrote in message
. com...
Hi Andt,

To answer your queries:

1. The rads I mention are not as old as the antique types you mention
so I guess I mean old versions of more modern panel types.

2. I thought it was the typical triangle shape heat distribution but
it also sounds a bit like the top only and either end of rad heating
you suggested (I get the impression I am, not beong clear!)- when we
cleaned one out last year, it worked perfectly for a couple of weeks
before going back to the orignal useless heat distribution.

3. Yes, the new rads are in BTU/hr so I guess the existing pipes
should be ok. Phew.

I think we'll get a bloke round to change the rads and see how we get
on then. Fingers crossed it will be fine!

And get a powerflush on "all" pipes.

For this it is worth shopping around. BG charge outrageous prices.
It is also possible to hire the equipment and chemicals.

Then run the system on 80C all the
time. If you are getting new rads get low surface temperature rads as these
can be safely run at 80C.

Any radiator can be safely run at 80 degrees as long as you don't
touch it.





---

..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
news
On Wed, 20 Aug 2003 20:53:50 +0100, "IMM" wrote:


"Rebecca" wrote in message
. com...
Hi Andt,

To answer your queries:

1. The rads I mention are not as old as the antique types you mention
so I guess I mean old versions of more modern panel types.

2. I thought it was the typical triangle shape heat distribution but
it also sounds a bit like the top only and either end of rad heating
you suggested (I get the impression I am, not beong clear!)- when we
cleaned one out last year, it worked perfectly for a couple of weeks
before going back to the orignal useless heat distribution.

3. Yes, the new rads are in BTU/hr so I guess the existing pipes
should be ok. Phew.

I think we'll get a bloke round to change the rads and see how we get
on then. Fingers crossed it will be fine!

And get a powerflush on "all" pipes.

For this it is worth shopping around. BG charge outrageous prices.
It is also possible to hire the equipment and chemicals.

Then run the system on 80C all the
time. If you are getting new rads get low surface temperature rads as
these
can be safely run at 80C.

Any radiator can be safely run at 80 degrees as long as you don't
touch it.

You can touch LST rads, which is also good for children.


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"Andy Hall" wrote in message
...
On Wed, 20 Aug 2003 22:47:54 +0100, "IMM" wrote:

. If you are getting new rads get low surface temperature rads as
these
can be safely run at 80C.

Any radiator can be safely run at 80 degrees as long as you don't
touch it.

You can touch LST rads, which is also good for children.


You can touch any radiator at 80 degrees and unless infirm in some way
will move your hand by reflex before any damage is done.

Children do this precisely once, and there is no need to mollycoddle
them.

There is no magic about LST radiators versus putting a standard
radiator in a cabinet. If you compare Myson LST radiators with the
equivalent sized Premier HE, the output is about a third less for the
same size.
This is similar to the recommended derating factor for cabinets.

But cabinets look naff


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Rebecca wrote:

Very useful information Andy. Thanks.

I wonder if a bit more info will narrow it down then...

Our house has a mixture of new and old steel rads. The new ones are
fine (not as hot as they could be but they heat up more or less
evenly), but the steel rads are heating very badly (only the top 2
inches)- despite us removing them last year and cleaning them
thoroughly (and cleaning the system with Fernox etc).

So, we were recommended to buy new rads to replace these old ones,
which we have done - I must admit the plumber who told us the sizes to
buy did guestimate. Looking at the B&G catalogue, the output of these
4 new rads ranges from 4500 to 6200. 3 of them are currently on 8mm,
and the smallest is on 6mm.

From your figures Andy if the general rule of thumb applies, it looks
like we will have to replace most of the pipes (as 8mm generally deals
with up to 4500w). Have I interpreted this correct?

The plumber that recommended changing all the pipes to 15mm (but did
not recommend changing the rads) was the only one which was
recommended to us.

Your opinion with this extra bit of info would be much appreciated!

Changing tac slightly 0 another plumber told us that we would have to
change the pipes coming form the boiler (some sort of Potterton) from
22mm to 28mm and that is why the circulation is bad. This sounds dodgy
to me...we had about 6 plumbers round and no-one mentioned this. What
do you think?

Thanks
Rebecca

I think that unless the boiler is rated at 35kW or more then the 22mm
pipe will be fine.

Over all it sound as if they system needs rebalancing and the 6mm pipe
upgrading (becasue the slightest debris would have a really big effect
on it, I guess it is perhaps only 1/3 the area of the 8mm pipe
_internally_.

The guy that wants to do all 15mm is likely being over cautious - the
system nearly works.

I'd probably choose to upgrade the 6mm pipe to 8 or 15 (depending on the
layout), leave everything else as is and then spend time rebalancing the
system to get the 'old' rads to heat up (the water is taking the easy
route thru the 15mm new stuff).

"Ed Sirett" wrote in message
...
Rebecca wrote:

Very useful information Andy. Thanks.

I wonder if a bit more info will narrow it down then...

Our house has a mixture of new and old steel rads. The new ones are
fine (not as hot as they could be but they heat up more or less
evenly), but the steel rads are heating very badly (only the top 2
inches)- despite us removing them last year and cleaning them
thoroughly (and cleaning the system with Fernox etc).

So, we were recommended to buy new rads to replace these old ones,
which we have done - I must admit the plumber who told us the sizes to
buy did guestimate. Looking at the B&G catalogue, the output of these
4 new rads ranges from 4500 to 6200. 3 of them are currently on 8mm,
and the smallest is on 6mm.

From your figures Andy if the general rule of thumb applies, it looks
like we will have to replace most of the pipes (as 8mm generally deals
with up to 4500w). Have I interpreted this correct?

The plumber that recommended changing all the pipes to 15mm (but did
not recommend changing the rads) was the only one which was
recommended to us.

Your opinion with this extra bit of info would be much appreciated!

Changing tac slightly 0 another plumber told us that we would have to
change the pipes coming form the boiler (some sort of Potterton) from
22mm to 28mm and that is why the circulation is bad. This sounds dodgy
to me...we had about 6 plumbers round and no-one mentioned this. What
do you think?

Thanks
Rebecca

I think that unless the boiler is rated at 35kW or more then the 22mm
pipe will be fine.

Over all it sound as if they system needs rebalancing and the 6mm pipe
upgrading (becasue the slightest debris would have a really big effect
on it, I guess it is perhaps only 1/3 the area of the 8mm pipe
_internally_.

The guy that wants to do all 15mm is likely being over cautious - the
system nearly works.

I'd probably choose to upgrade the 6mm pipe to 8 or 15 (depending on the
layout), leave everything else as is and then spend time rebalancing the
system to get the 'old' rads to heat up (the water is taking the easy
route thru the 15mm new stuff).

I would leave the pipes alone, as they worked fine at one time. They
obviously need cleaning, so cleaning is a priority. I would also put a
strainer on the return to the boiler to collect any debris in the system
which will save the boiler and pipes. Then balance.





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Andy Hall wrote:
=


=

For this it is worth shopping around. BG charge outrageous prices.
It is also possible to hire the equipment and chemicals.
=

Quote today to replace a balanced flue combi with a new Valliant
fan-flued combi + make good ship lap boards on the outside. =


Me =A31500. =

BG =A32532. (I thought they would be around =A32250). =


-- =

Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html

On Wed, 20 Aug 2003 23:54:35 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Wed, 20 Aug 2003 22:47:54 +0100, "IMM" wrote:

. If you are getting new rads get low surface temperature rads as
these
can be safely run at 80C.

Any radiator can be safely run at 80 degrees as long as you don't
touch it.

You can touch LST rads, which is also good for children.


You can touch any radiator at 80 degrees and unless infirm in some way
will move your hand by reflex before any damage is done.

Children do this precisely once, and there is no need to mollycoddle
them.

There is no magic about LST radiators versus putting a standard
radiator in a cabinet. If you compare Myson LST radiators with the
equivalent sized Premier HE, the output is about a third less for the
same size.
This is similar to the recommended derating factor for cabinets.

But cabinets look naff

I agree, but radiators are hardly things of beauty anyway, are they?



..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Wed, 20 Aug 2003 23:54:35 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Wed, 20 Aug 2003 22:47:54 +0100, "IMM" wrote:

. If you are getting new rads get low surface temperature rads as
these
can be safely run at 80C.

Any radiator can be safely run at 80 degrees as long as you don't
touch it.

You can touch LST rads, which is also good for children.


You can touch any radiator at 80 degrees and unless infirm in some way
will move your hand by reflex before any damage is done.

Children do this precisely once, and there is no need to mollycoddle
them.

There is no magic about LST radiators versus putting a standard
radiator in a cabinet. If you compare Myson LST radiators with the
equivalent sized Premier HE, the output is about a third less for the
same size.
This is similar to the recommended derating factor for cabinets.

But cabinets look naff

I agree, but radiators are hardly things of beauty anyway, are they?

Have you seen the designer rads these days?


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On Thu, 21 Aug 2003 10:38:20 +0100, "IMM" wrote:



You can touch any radiator at 80 degrees and unless infirm in some way
will move your hand by reflex before any damage is done.

Children do this precisely once, and there is no need to mollycoddle
them.

There is no magic about LST radiators versus putting a standard
radiator in a cabinet. If you compare Myson LST radiators with the
equivalent sized Premier HE, the output is about a third less for the
same size.
This is similar to the recommended derating factor for cabinets.

But cabinets look naff

I agree, but radiators are hardly things of beauty anyway, are they?

Have you seen the designer rads these days?


Yes. I think that the futuristic looking ones look especially
hideous.

I did take a look at a Myson product that had a wooden bench across
the top that I was considering for the conservatory at one point.

The trouble was that it was over £1600 exc. discounted.




---

..andy

To email, substitute .nospam with .gl

"David" wrote in message
om...
Andy Hall wrote in message
. ..
On Wed, 20 Aug 2003 22:47:54 +0100, "IMM" wrote:

. If you are getting new rads get low surface temperature rads as
these
can be safely run at 80C.

Any radiator can be safely run at 80 degrees as long as you don't
touch it.

You can touch LST rads, which is also good for children.


You can touch any radiator at 80 degrees and unless infirm in some way
will move your hand by reflex before any damage is done.

The key word being "infirm"... there was a nasty accident at an nearby
old people's home recently where a resident got out of bed during the
night and fell against a overly hot radiator, and unable to summon
help quickly, died from the resulting burns.

Children do this precisely once, and there is no need to mollycoddle
them.

Well y-e-s, but consider an uncoordinated toddler, just taking his
first steps, who falls against a hot radiator (bare chest/back?). I'd
say it's likely to take him long enough to disengage himself to cause
burns.

IMHO running a normal rad at 80 deg is fine providing you are in an
environment free of the very young or very old; but shouldn't be
recommended as "standard" practice.

The whole non-condensing heating system is designed to run at this temp.
Even some condensing boilers designed to maintain an old 80C system, in that
it will run it 80C if it needs to. Since 1980 Sweden and Denmark have
standardised on a 60C max rad temp.


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