Is there any regulatory or other obvious reason to locate CH sealed system
components physically close together as is achieved with a sealed system kit,
or is it acceptable to separate them?

e.g. expansion vessel located remotely from other components.

Obviously the pressure gauge ought to be visible from the filling loop valve
position.

In article ,
Andy Hall writes:
Is there any regulatory or other obvious reason to locate CH sealed system
components physically close together as is achieved with a sealed system kit,
or is it acceptable to separate them?

e.g. expansion vessel located remotely from other components.

Obviously the pressure gauge ought to be visible from the filling loop valve
position.

ISTR that when I was wading through lots of boiler installation
instructions when choosing a boiler, a number of them required
the expansion vessel in the return near the boiler. I doubt that's
a regulatory issue -- probably something more like ensuring there
was no momentary pressure drop in the boiler when pump started
that might otherwise trip a lockout due to low system pressure.

--
Andrew Gabriel

On Sat, 15 Jul 2006 01:59:01 +0100, Andrew Gabriel wrote
(in article ):

In article ,
Andy Hall writes:
Is there any regulatory or other obvious reason to locate CH sealed system
components physically close together as is achieved with a sealed system
kit,
or is it acceptable to separate them?

e.g. expansion vessel located remotely from other components.

Obviously the pressure gauge ought to be visible from the filling loop
valve
position.

ISTR that when I was wading through lots of boiler installation
instructions when choosing a boiler, a number of them required
the expansion vessel in the return near the boiler. I doubt that's
a regulatory issue -- probably something more like ensuring there
was no momentary pressure drop in the boiler when pump started
that might otherwise trip a lockout due to low system pressure.



I looked as well and couldn't find anything. The items to make a system
are available separately.

The relief valve needs to have a suitable exit but I couldn't see a reason
that it needs to be next to the expansion vessel. I also couldn't see a
reason why the filling loop has to be near either apart from the point about
seeing the gauge when filling. Obviously the filling loop has to be a
proper one with check valve etc.

"Andy Hall" wrote in message
...
On Sat, 15 Jul 2006 01:59:01 +0100, Andrew Gabriel wrote
(in article ):

In article ,
Andy Hall writes:
Is there any regulatory or other obvious reason to locate CH sealed
system
components physically close together as is achieved with a sealed system
kit,
or is it acceptable to separate them?

e.g. expansion vessel located remotely from other components.

Obviously the pressure gauge ought to be visible from the filling loop
valve
position.

ISTR that when I was wading through lots of boiler installation
instructions when choosing a boiler, a number of them required
the expansion vessel in the return near the boiler. I doubt that's
a regulatory issue -- probably something more like ensuring there
was no momentary pressure drop in the boiler when pump started
that might otherwise trip a lockout due to low system pressure.



I looked as well and couldn't find anything. The items to make a system
are available separately.

The relief valve needs to have a suitable exit but I couldn't see a reason
that it needs to be next to the expansion vessel. I also couldn't see a
reason why the filling loop has to be near either apart from the point
about
seeing the gauge when filling. Obviously the filling loop has to be a
proper one with check valve etc.

The source of expansion is the heat source, the boiler. The relief valve
has to be where the highest pressure point would be, the flow right on the
boiler. The expansion vessel has to be where the expansion would be
greatest, the boiler. Before system boilers came along, and all kit was
loose, the expansion was always on the flow. On the return, keeps it cooler
and Andrew hit on one the points it goes near the boiler. The expansion
vessel can add pressure when a negative pressure is around it. On the
suction side of the pump, when pressure drops compared to the pressure side,
it will expand back into the system equalising the pressure difference
around the pump somewhat. On an open vented system there may be sharp
differences in pressure from the highest to the lowest pressure around the
system as the expansion rise up the expansion pipe and nothing comes down to
compensate. The expansion vessel compensates to reduce negative pressure.

On an open vented system with a low head cavitation may occur in some pump
models. Having the charge pressure as high as possible in a sealed system
prevents pump cavitation (also this reduces as oxygen is eliminated from the
system), and also the higher pressure makes the boiler quieter as it raises
the boiling point. In some small capacity boilers there is local boiling of
the water in the heat exchanger giving the hiss sound. A higher pressure
prevents the boiler hissing.

Inhibitor can also cause system noise too. It may be wroth eliminating
inhibitor with a sealed system. The inhibitor swells joint seals and over
time causes leaks. In some Continental countries it is used infrequently.

Well, I wouldn't normally respond, but since you mention me,
I'd better make it clear where I stand...

In article ews.net,
"Doctor Drivel" writes:

The source of expansion is the heat source, the boiler. The relief valve
has to be where the highest pressure point would be, the flow right on the
boiler. The expansion vessel has to be where the expansion would be
greatest, the boiler.

Oh dear -- every single statement incorrect.

Before system boilers came along, and all kit was
loose, the expansion was always on the flow. On the return, keeps it cooler
and Andrew hit on one the points it goes near the boiler. The expansion
vessel can add pressure when a negative pressure is around it. On the
suction side of the pump, when pressure drops compared to the pressure side,
it will expand back into the system equalising the pressure difference
around the pump somewhat.

The point was that in the initial fraction of a second when the
pump starts and there's not yet any flow, you will get a significant
momentary pressure drop (which in turn is responsible for starting
the flow round the system). This is not of any consequence as it lasts
only a fraction of a second, except it could trip an under pressure
sensor, and cause a lockout. The pressure vessel will significantly
reduce this pressure drop if there's a short path between it and
the pressure sensor. For this purpose, it's probably more important
to have it near the under-pressure sensore than the pump. You might
get similar effects as zone valves open/close when the pump is running.

On an open vented system there may be sharp
differences in pressure from the highest to the lowest pressure around the
system as the expansion rise up the expansion pipe and nothing comes down to
compensate. The expansion vessel compensates to reduce negative pressure.

That paragraph is rubbish, and there is no expansion vessel in
open vented systems (the header tank performs that function).

On an open vented system with a low head cavitation may occur in some pump
models. Having the charge pressure as high as possible in a sealed system
prevents pump cavitation

Gosh, that's actually right (but largely irrelevant).

(also this reduces as oxygen is eliminated from the
system), and also the higher pressure makes the boiler quieter as it raises
the boiling point. In some small capacity boilers there is local boiling of
the water in the heat exchanger giving the hiss sound. A higher pressure
prevents the boiler hissing.

Inhibitor can also cause system noise too. It may be wroth eliminating
inhibitor with a sealed system. The inhibitor swells joint seals and over
time causes leaks. In some Continental countries it is used infrequently.

This voids pretty well all boiler guarantees.

--
Andrew Gabriel

In article ,
Andy Hall writes:

The relief valve needs to have a suitable exit but I couldn't see a reason
that it needs to be next to the expansion vessel. I also couldn't see a

I don't think I've seen any such claim, but I would put
it close to the boiler exit (about 3" away in the case
of the one I fitted).

Whilst sitting at some traffic lights, I was looking at
the row of terraced houses along the road. On one, there
was the classic pattern of gas pipe, flue, and pressure
relief exit pipe indicative of a sealed system boiler
on the inside. However, what caused me to do a double-
take was that the pressure relief exit pipe was pushfit
plastic with a pushfit elbow and an extra 6" of pushfit
pipe pointing it downwards (and with no bracket holding
it in place). The house wall only about a foot back from
the pavement edge.

Then I got to thinking. I suppose there's no point in a
metal pressure relief pipe if the system itself is all
pushfit indoors, although I don't think I've ever seen
a plastic pressure relief pipe before.

--
Andrew Gabriel

"Andrew Gabriel" wrote in message
...
In article ,
Andy Hall writes:

The relief valve needs to have a suitable exit but I couldn't see a
reason
that it needs to be next to the expansion vessel. I also couldn't see
a

I don't think I've seen any such claim, but I would put
it close to the boiler exit (about 3" away in the case
of the one I fitted).

Whilst sitting at some traffic lights, I was looking at
the row of terraced houses along the road. On one, there
was the classic pattern of gas pipe, flue, and pressure
relief exit pipe indicative of a sealed system boiler
on the inside. However, what caused me to do a double-
take was that the pressure relief exit pipe was pushfit
plastic with a pushfit elbow and an extra 6" of pushfit
pipe pointing it downwards (and with no bracket holding
it in place). The house wall only about a foot back from
the pavement edge.

Then I got to thinking. I suppose there's no point in a
metal pressure relief pipe if the system itself is all
pushfit indoors, although I don't think I've ever seen
a plastic pressure relief pipe before.

It has to be metal, no need for sleeving through a wall, and terminate at
floor level with the pipe turned towards the wall (an elbow). It can
terminate at high level like at the eves when a boiler is fitted in the
loft, but must turn in on itself. and it must not be over a used pathway.
It can be terminated onto a flat roof too without turning into the wall.

The HSE should be called in to this house. If it blows it could scald
people in the street below.

On Sat, 15 Jul 2006 13:27:20 +0100, Doctor Drivel wrote
(in article ews.net):


"Andrew Gabriel" wrote in message
...
In article ,
Andy Hall writes:

The relief valve needs to have a suitable exit but I couldn't see a
reason
that it needs to be next to the expansion vessel. I also couldn't see
a

I don't think I've seen any such claim, but I would put
it close to the boiler exit (about 3" away in the case
of the one I fitted).

Whilst sitting at some traffic lights, I was looking at
the row of terraced houses along the road. On one, there
was the classic pattern of gas pipe, flue, and pressure
relief exit pipe indicative of a sealed system boiler
on the inside. However, what caused me to do a double-
take was that the pressure relief exit pipe was pushfit
plastic with a pushfit elbow and an extra 6" of pushfit
pipe pointing it downwards (and with no bracket holding
it in place). The house wall only about a foot back from
the pavement edge.

Then I got to thinking. I suppose there's no point in a
metal pressure relief pipe if the system itself is all
pushfit indoors, although I don't think I've ever seen
a plastic pressure relief pipe before.

It has to be metal, no need for sleeving through a wall, and terminate at
floor level with the pipe turned towards the wall (an elbow). It can
terminate at high level like at the eves when a boiler is fitted in the
loft, but must turn in on itself. and it must not be over a used pathway.
It can be terminated onto a flat roof too without turning into the wall.

Do you have a reference?

Andy Hall wrote:
Is there any regulatory or other obvious reason to locate CH sealed system
components physically close together as is achieved with a sealed system kit,
or is it acceptable to separate them?

e.g. expansion vessel located remotely from other components.

When we had our Vaillant fitted a few years ago, I'm fairly sure the
installation instructions permitted/suggested the expansion vessel to be
sited near the boiler downstairs, as opposed to the tank upstairs (which
is where we wanted it, and where it went).

If you don't get a definitive answer here I'll have a root around and
see if I can dig them out.

David

On Sat, 15 Jul 2006 10:30:15 +0100, Lobster wrote
(in article ):

Andy Hall wrote:
Is there any regulatory or other obvious reason to locate CH sealed system
components physically close together as is achieved with a sealed system
kit,
or is it acceptable to separate them?

e.g. expansion vessel located remotely from other components.

When we had our Vaillant fitted a few years ago, I'm fairly sure the
installation instructions permitted/suggested the expansion vessel to be
sited near the boiler downstairs, as opposed to the tank upstairs (which
is where we wanted it, and where it went).

If you don't get a definitive answer here I'll have a root around and
see if I can dig them out.

David

Thanks David

I am pretty sure that that isn't' an issue, although note Andrew's point.

I was thinking about separation of the individual components such as the
expansion vessel, the filling point, the pressure gauge and the relief valve.
These often come as a kit, but I can't ind anything that says that they have
to be co-located. The components are available separately as well.

On Sat, 15 Jul 2006 11:08:48 +0100, Andy Hall wrote:

On Sat, 15 Jul 2006 10:30:15 +0100, Lobster wrote
(in article ):

Andy Hall wrote:
Is there any regulatory or other obvious reason to locate CH sealed system
components physically close together as is achieved with a sealed system
kit,
or is it acceptable to separate them?

e.g. expansion vessel located remotely from other components.

When we had our Vaillant fitted a few years ago, I'm fairly sure the
installation instructions permitted/suggested the expansion vessel to be
sited near the boiler downstairs, as opposed to the tank upstairs (which
is where we wanted it, and where it went).

If you don't get a definitive answer here I'll have a root around and
see if I can dig them out.

David

Thanks David

I am pretty sure that that isn't' an issue, although note Andrew's point.

I was thinking about separation of the individual components such as the
expansion vessel, the filling point, the pressure gauge and the relief valve.
These often come as a kit, but I can't ind anything that says that they have
to be co-located. The components are available separately as well.

It certainly is often convenient to put the expansion vessel in the
loft when "rolling you own" sealed system.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Fri, 14 Jul 2006 23:43:49 +0100, Andy Hall wrote:

Is there any regulatory or other obvious reason to locate CH sealed system
components physically close together as is achieved with a sealed system kit,
or is it acceptable to separate them?

e.g. expansion vessel located remotely from other components.

Obviously the pressure gauge ought to be visible from the filling loop valve
position.

There is I beleive a BS for this. I suppose it might be useful to obtain a
copy someday. However most boiler installation instructions are somewhat
schematic in this area, many favour putting the vessel on the return
(probably because the pump is on the return in the boiler.

The Potty Suprima wants the components on the flow before the external
pump.

My guess is that th expansion vessel before the pump makes sure that the
pump operation increases rather than decreases internal pressure in the
circuit.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Sun, 16 Jul 2006 00:08:35 +0100, Ed Sirett wrote
(in article .uk):

On Fri, 14 Jul 2006 23:43:49 +0100, Andy Hall wrote:

Is there any regulatory or other obvious reason to locate CH sealed system
components physically close together as is achieved with a sealed system
kit,
or is it acceptable to separate them?

e.g. expansion vessel located remotely from other components.

Obviously the pressure gauge ought to be visible from the filling loop
valve
position.

There is I beleive a BS for this. I suppose it might be useful to obtain a
copy someday. However most boiler installation instructions are somewhat
schematic in this area, many favour putting the vessel on the return
(probably because the pump is on the return in the boiler.

The Potty Suprima wants the components on the flow before the external
pump.

My guess is that th expansion vessel before the pump makes sure that the
pump operation increases rather than decreases internal pressure in the
circuit.



Thanks Ed.

This is somewhat akin to Andrew's point, I think.

I have to drain my system to exchange a radiator for a different type in a
different place, so while doing so decided that some moving of these
components would be useful too. I can easily position the vessel
appropriately, but wanted to make the tee in for filling in a different
place. I can't see a reason why the two can't be separated, but thought
I'd ask in case there was a specific regulatory reason.

On Sun, 16 Jul 2006 00:25:59 +0100, Andy Hall wrote:

On Sun, 16 Jul 2006 00:08:35 +0100, Ed Sirett wrote
(in article .uk):

On Fri, 14 Jul 2006 23:43:49 +0100, Andy Hall wrote:

Is there any regulatory or other obvious reason to locate CH sealed system
components physically close together as is achieved with a sealed system
kit,
or is it acceptable to separate them?

e.g. expansion vessel located remotely from other components.

Obviously the pressure gauge ought to be visible from the filling loop
valve
position.

There is I beleive a BS for this. I suppose it might be useful to obtain a
copy someday. However most boiler installation instructions are somewhat
schematic in this area, many favour putting the vessel on the return
(probably because the pump is on the return in the boiler.

The Potty Suprima wants the components on the flow before the external
pump.

My guess is that th expansion vessel before the pump makes sure that the
pump operation increases rather than decreases internal pressure in the
circuit.



Thanks Ed.

This is somewhat akin to Andrew's point, I think.

I have to drain my system to exchange a radiator for a different type in a
different place, so while doing so decided that some moving of these
components would be useful too. I can easily position the vessel
appropriately, but wanted to make the tee in for filling in a different
place. I can't see a reason why the two can't be separated, but thought
I'd ask in case there was a specific regulatory reason.

Looks like BS 6798 is not worried about the location of the filling loop.




--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Sun, 16 Jul 2006 08:17:52 +0100, Ed Sirett wrote
(in article .uk):

On Sun, 16 Jul 2006 00:25:59 +0100, Andy Hall wrote:

On Sun, 16 Jul 2006 00:08:35 +0100, Ed Sirett wrote
(in article .uk):

On Fri, 14 Jul 2006 23:43:49 +0100, Andy Hall wrote:

Is there any regulatory or other obvious reason to locate CH sealed
system
components physically close together as is achieved with a sealed system
kit,
or is it acceptable to separate them?

e.g. expansion vessel located remotely from other components.

Obviously the pressure gauge ought to be visible from the filling loop
valve
position.

There is I beleive a BS for this. I suppose it might be useful to obtain a
copy someday. However most boiler installation instructions are somewhat
schematic in this area, many favour putting the vessel on the return
(probably because the pump is on the return in the boiler.

The Potty Suprima wants the components on the flow before the external
pump.

My guess is that th expansion vessel before the pump makes sure that the
pump operation increases rather than decreases internal pressure in the
circuit.



Thanks Ed.

This is somewhat akin to Andrew's point, I think.

I have to drain my system to exchange a radiator for a different type in a
different place, so while doing so decided that some moving of these
components would be useful too. I can easily position the vessel
appropriately, but wanted to make the tee in for filling in a different
place. I can't see a reason why the two can't be separated, but thought
I'd ask in case there was a specific regulatory reason.

Looks like BS 6798 is not worried about the location of the filling loop.

Good. Thanks for that, Ed. I couldn't see a reason that it would matter.

I am now seriously concerned about the vessel location. I think I'd
better remove one of the kitchen cupboards so that I can fit it high on the
wall next to the boiler flow within a few cm of the boiler itself. Do you
know if Plumbcenter offer expansion vessels in Farrow and Ball colours? ;-)

In article ,
Andy Hall writes:

I am now seriously concerned about the vessel location. I think I'd
better remove one of the kitchen cupboards so that I can fit it high on the
wall next to the boiler flow within a few cm of the boiler itself. Do you

Is that shortly before the pump (external I presume)?

know if Plumbcenter offer expansion vessels in Farrow and Ball colours? ;-)

What about fitting it inside one of the cupboards?

Also, if my hypothsis is correct, then it would appear your
boiler has not been affected by low pressure lockout, in
which case moving it would not seem to be required in your
case. Another option would be to leave it where it is, and
add a small one in the pipework at the desired location
(which would use up even less cupboard space).

--
Andrew Gabriel

On Sun, 16 Jul 2006 08:32:17 +0100, Andy Hall wrote:

On Sun, 16 Jul 2006 08:17:52 +0100, Ed Sirett wrote
(in article .uk):

On Sun, 16 Jul 2006 00:25:59 +0100, Andy Hall wrote:

On Sun, 16 Jul 2006 00:08:35 +0100, Ed Sirett wrote
(in article .uk):

On Fri, 14 Jul 2006 23:43:49 +0100, Andy Hall wrote:

Is there any regulatory or other obvious reason to locate CH sealed
system
components physically close together as is achieved with a sealed system
kit,
or is it acceptable to separate them?

e.g. expansion vessel located remotely from other components.

Obviously the pressure gauge ought to be visible from the filling loop
valve
position.

There is I beleive a BS for this. I suppose it might be useful to obtain a
copy someday. However most boiler installation instructions are somewhat
schematic in this area, many favour putting the vessel on the return
(probably because the pump is on the return in the boiler.

The Potty Suprima wants the components on the flow before the external
pump.

My guess is that th expansion vessel before the pump makes sure that the
pump operation increases rather than decreases internal pressure in the
circuit.



Thanks Ed.

This is somewhat akin to Andrew's point, I think.

I have to drain my system to exchange a radiator for a different type in a
different place, so while doing so decided that some moving of these
components would be useful too. I can easily position the vessel
appropriately, but wanted to make the tee in for filling in a different
place. I can't see a reason why the two can't be separated, but thought
I'd ask in case there was a specific regulatory reason.

Looks like BS 6798 is not worried about the location of the filling loop.

Good. Thanks for that, Ed. I couldn't see a reason that it would matter.

I am now seriously concerned about the vessel location. I think I'd
better remove one of the kitchen cupboards so that I can fit it high on the
wall next to the boiler flow within a few cm of the boiler itself. Do you
know if Plumbcenter offer expansion vessels in Farrow and Ball colours? ;-)

Does the boiler instructions say anything about where the vessel should go?
If so they 'trump' any requirements of BS 6798.

If the system pressure is reasonable (1-1.5 bar) then even if the pump
came before the vessel then the reduction in circuit pressure would not be
that significant.




--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards