"Andy Hall" wrote in message
...
On Tue, 19 Oct 2004 22:05:42 +0100, "JJJ" wrote:

"Colin Wilson" wrote in message
et...
If I can get my sealed system up to at least 1.5bar by filling it
from
the
mains filling loop, does this mean I have enough pressure to fit a
combi
boiler?

What kind of flow do you get from your taps in litres per minute ?

9 litres a minute from the kitchen tap (the rest are off the cold water
tank)



Then the answer is that the results will be disappointing. You
could look at getting the supply improved or perhaps the stop tap is
partly closed. This is the lowest legal minimum for a water supply.

Generally for a mains fed system, you need at least 20lpm.

If you must use a combi because you would like to get rid of the HW
cylinder, then look at one that will accept its water feed from a roof
tank.

Check that if you have a stopcock or isolation valve/tap in the line that it
is
fully open. My initial flow rates were rather disappointing until I realised
that
the combi was fed from an isolation tap, which was only cracked open
halfway.

Andy.

If I can get my sealed system up to at least 1.5bar by filling it from the
mains filling loop, does this mean I have enough pressure to fit a combi
boiler?

Jim

If I can get my sealed system up to at least 1.5bar by filling it from the
mains filling loop, does this mean I have enough pressure to fit a combi
boiler?

What kind of flow do you get from your taps in litres per minute ?

--
Please add "[newsgroup]" in the subject of any personal replies via email
--- My new email address has "ngspamtrap" & @btinternet.com in it ;-) ---

"Colin Wilson" wrote in message
t...
If I can get my sealed system up to at least 1.5bar by filling it from
the
mains filling loop, does this mean I have enough pressure to fit a combi
boiler?

What kind of flow do you get from your taps in litres per minute ?

9 litres a minute from the kitchen tap (the rest are off the cold water
tank)

In an earlier contribution to this discussion,
JJJ wrote:

If I can get my sealed system up to at least 1.5bar by filling it
from the mains filling loop, does this mean I have enough pressure to
fit a combi boiler?

Jim

No! It simply tells you that you have a *static* pressure of at least
1.5bar. It tells you nothing about the *flow rate* which your mains supply
can sustain.

I think the pundits say that you need about 20 litres per minute.

--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

On Tue, 19 Oct 2004 22:05:42 +0100, "JJJ" wrote:

"Colin Wilson" wrote in message
et...
If I can get my sealed system up to at least 1.5bar by filling it from
the
mains filling loop, does this mean I have enough pressure to fit a combi
boiler?

What kind of flow do you get from your taps in litres per minute ?

9 litres a minute from the kitchen tap (the rest are off the cold water
tank)



Then the answer is that the results will be disappointing. You
could look at getting the supply improved or perhaps the stop tap is
partly closed. This is the lowest legal minimum for a water supply.

Generally for a mains fed system, you need at least 20lpm.

If you must use a combi because you would like to get rid of the HW
cylinder, then look at one that will accept its water feed from a roof
tank.


..andy

To email, substitute .nospam with .gl

"andrewpreece" wrote in message
...

"Andy Hall" wrote in message
...
On Tue, 19 Oct 2004 22:05:42 +0100, "JJJ" wrote:

"Colin Wilson" wrote in message
et...
If I can get my sealed system up to at least 1.5bar by filling it
from
the
mains filling loop, does this mean I have enough pressure to fit a
combi
boiler?

What kind of flow do you get from your taps in litres per minute ?

9 litres a minute from the kitchen tap (the rest are off the cold water
tank)



Then the answer is that the results will be disappointing. You
could look at getting the supply improved or perhaps the stop tap is
partly closed. This is the lowest legal minimum for a water supply.

Generally for a mains fed system, you need at least 20lpm.

If you must use a combi because you would like to get rid of the HW
cylinder, then look at one that will accept its water feed from a roof
tank.

Check that if you have a stopcock or isolation valve/tap in the line that
it
is
fully open. My initial flow rates were rather disappointing until I
realised
that
the combi was fed from an isolation tap, which was only cracked open
halfway.

Andy.

will do. thanks,

Jim

If I can get my sealed system up to at least 1.5bar by filling it from the
mains filling loop, does this mean I have enough pressure to fit a combi
boiler?

Yes it does. 1.5 bar is easily enough for a combi boiler. However, it
doesn't tell you if the flow rate is good enough. Flow rate is more
important than the pressure. You mention 9 lpm elsewhere, which is not
enough flow rate. However, this poor flow rate might be for a fixable
reason, such as a broken/partially closed stopcock, or a modern styled tap
with very narrow waterways that is not designed to pass more than that flow
rate. (I'm not suggesting that the tap would need replacing, just that it
might affect the feasibility test).

If you have a garden tap, try measuring the flow rate off that instead.

Christian.

andrewpreece wrote:


Check that if you have a stopcock or isolation valve/tap in the line that it
is
fully open. My initial flow rates were rather disappointing until I realised
that
the combi was fed from an isolation tap, which was only cracked open
halfway.

Some combis control the flow rate of hot water produced, some dont.
Hence in winter (i.e. cold incoming water), the ones with control will
produce water at the same temperature as before, but a lower flow rate.
The ones without control will produce water at the same rate as before,
but at a lower temperature.

Sometimes I have seen the input stopcock partially turned off like this
on boilers that do not limit hot water flow rate so as to ensure the hot
water temperature remains hot enough without the user having to remember
not to turn the hot bath tap full on.

--
Cheers,

John.

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

"Christian McArdle" wrote in message
. net...
If I can get my sealed system up to at least 1.5bar by filling it from
the
mains filling loop, does this mean I have enough pressure to fit a combi
boiler?

Yes it does. 1.5 bar is easily enough for a combi boiler. However, it
doesn't tell you if the flow rate is good enough. Flow rate is more
important than the pressure. You mention 9 lpm elsewhere, which is not
enough flow rate. However, this poor flow rate might be for a fixable
reason, such as a broken/partially closed stopcock, or a modern styled tap
with very narrow waterways that is not designed to pass more than that
flow
rate. (I'm not suggesting that the tap would need replacing, just that it
might affect the feasibility test).

If you have a garden tap, try measuring the flow rate off that instead.

Christian.

ok, I've measured it at 15 litres/min outside at the garden tap. Better,
but not outstanding....

Jim

ok, I've measured it at 15 litres/min outside at the garden tap. Better,
but not outstanding....

I think that`s similar to ours, and recently had our first central
heating system installed - a Worcester Bosch 28 SiII IIRC...

Works just fine :-)

--
Please add "[newsgroup]" in the subject of any personal replies via email
--- My new email address has "ngspamtrap" & @btinternet.com in it ;-) ---

In message , John
Rumm writes
andrewpreece wrote:


Check that if you have a stopcock or isolation valve/tap in the line that it
is
fully open. My initial flow rates were rather disappointing until I realised
that
the combi was fed from an isolation tap, which was only cracked open
halfway.

Some combis control the flow rate of hot water produced,

Which ones and how ?

I can't think of any.

Every boiler I can think of which has dynamic control over the DHW
temperature does this using a modureg - a gas valve which varies it's
output depending on the temperature of the water coming out of the heat
exchanger



The information contained in this post
may not be published in, or used by
http://www.diyprojects.info



--
geoff

On Wed, 20 Oct 2004 20:32:56 +0100, "JJJ" wrote:

"Christian McArdle" wrote in message


If you have a garden tap, try measuring the flow rate off that instead.

Christian.

ok, I've measured it at 15 litres/min outside at the garden tap. Better,
but not outstanding....

Jim




It suggests that by some improvement to internal plumbing, perhaps
stop tap, etc. you could get a pretty good result.


..andy

To email, substitute .nospam with .gl

On Wed, 20 Oct 2004 21:47:59 +0100, Colin Wilson
wrote:

ok, I've measured it at 15 litres/min outside at the garden tap. Better,
but not outstanding....

I think that`s similar to ours, and recently had our first central
heating system installed - a Worcester Bosch 28 SiII IIRC...

Works just fine :-)



I guess that it depends on what your requirements and expectations
are.

A loft tank arrangement with 22mm pipework etc. can comfortably
deliver 15-20lpm per tap albeit at lowish pressure - with a pump
rather more.

If you are used to this, then 10-15lpm is going to seem poor.
OTOH, if you are used to an electric shower, it may appear brilliant.


..andy

To email, substitute .nospam with .gl

raden wrote:

Some combis control the flow rate of hot water produced,


Which ones and how ?

How? no idea, never studied one close enough...

I can't think of any.

They certainly seem much less common these days, I don't remember
finding any recent models that behave like this, the ones I have seen
have all been typically ten years old or more.

Every boiler I can think of which has dynamic control over the DHW
temperature does this using a modureg - a gas valve which varies it's
output depending on the temperature of the water coming out of the heat
exchanger

IIRC the Myson (monster sized thing, forget the model, but about 15
years old 120K BTU) that is mounted on the kitchen wall in my mum's
house would seem to be one. The multipoint(s) she had before that (one
was a Main "Severn Five") also regulated the water flow (to a feeble
trickle in winter!). Also I thing my current next door neighbours has an
(ageing) non modulating boiler that also seems to. I will have a closer
look at the model next time I am near it.

(IIRC our pet troll was insisting that his "Boiler of the Month" from a
few months ago (the CB50 was it?) would "never run cool" - so based on
that quality evidence perhaps you are right, there are no current
models! ;-) )

--
Cheers,

John.

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

"John Rumm" wrote in message
...
raden wrote:

Some combis control the flow rate of hot water produced,


Which ones and how ?

How? no idea, never studied one close enough...

I can't think of any.

They certainly seem much less common these days, I don't remember
finding any recent models that behave like this, the ones I have seen
have all been typically ten years old or more.

The Worcester Bosch Greentar combi 40kW, has flow regulator.IT can be set on
commissioning. You set the flow to the required litres/min and it stays
there. You can't turn the bath tap on full and just get warm water as the
simpler models do.

(the CB50 was it?) would "never
run cool" - so based on
that quality evidence perhaps you
are right, there are no current
models! ;-) )

What evidence would that be? The CB50 allows full belt then when the stored
water drops below a set level the water regulator maintains approx
11/litres/min flow through the unit.

The older HIghFlows don't run out of hot water, well on the older models you
had to lower the flow at the tap to heat the water up when the store was
exhausted.

On Wed, 20 Oct 2004 20:32:56 +0100, JJJ wrote:

"Christian McArdle" wrote in message
. net...
If I can get my sealed system up to at least 1.5bar by filling it from
the
mains filling loop, does this mean I have enough pressure to fit a combi
boiler?

Yes it does. 1.5 bar is easily enough for a combi boiler. However, it
doesn't tell you if the flow rate is good enough. Flow rate is more
important than the pressure. You mention 9 lpm elsewhere, which is not
enough flow rate. However, this poor flow rate might be for a fixable
reason, such as a broken/partially closed stopcock, or a modern styled tap
with very narrow waterways that is not designed to pass more than that
flow
rate. (I'm not suggesting that the tap would need replacing, just that it
might affect the feasibility test).

If you have a garden tap, try measuring the flow rate off that instead.

Christian.

ok, I've measured it at 15 litres/min outside at the garden tap. Better,
but not outstanding....

Not brilliant but likely workable.


--
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 Oct 2004 22:49:02 +0100, Andy Hall wrote:

On Wed, 20 Oct 2004 20:32:56 +0100, "JJJ" wrote:

"Christian McArdle" wrote in message


If you have a garden tap, try measuring the flow rate off that instead.

Christian.

ok, I've measured it at 15 litres/min outside at the garden tap. Better,
but not outstanding....

Jim




It suggests that by some improvement to internal plumbing, perhaps
stop tap, etc. you could get a pretty good result.


I agree that arttention to detail can make the difference here.
Using full bore 1/4 turn stop taps and getting the cold feed to the boiler
before other usags can make a difference.


--
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