We converted a five bed house in London for students and the plumber
put in a gas Vaillant turbomax plus 828 to serve a shower and a bath.
All the old pipe work from the old conventional system is still insitu
just blanked off. Frankly the combi is just poor; baths are just not
worth having and the shower flow is disturbed so much by washing
machines, dishwashers etc.I thought I could get away with it because we
all know students dont wash but this lot do....

I have read what you all say about combis but think that they are
useless for more than one old lady in a flat, I am afraid.

We now want to put in a an en suite shower room on the second floor,
exactly where the old airing cupboard/immersion heater was. The boiler
is on the ground floor in the kitchen and the existing bathroom is on
first floor.

I want to put a megaflow or similar unvented storage with an upgraded
new boiler.

The vaillant is nearly new and I wonder if some clever internal
rearrangement will turn it into a sealed system boiler or should I just
bite the bullet and buy a new proper one.

What do you reckon?

richman wrote:

The vaillant is nearly new and I wonder if some clever internal
rearrangement will turn it into a sealed system boiler or should I just
bite the bullet and buy a new proper one.

What do you reckon?

There is nothing to stop you using the combi just like a coventional
boiler with water heating driven (via zone valves etc) from the CH side
of it.

You could then either not use its DHW capability at all, or more
probably use it either for one of the showers (where it should work well
with no other demands on it to upset things), or perhaps things like
just feeding the kitchen where the (probably) shorter distance to the
taps would save having to run off so much before getting hot water.

--
Cheers,

John.

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

On 4 Aug 2005 02:50:04 -0700, "richman"
wrote:

We converted a five bed house in London for students and the plumber
put in a gas Vaillant turbomax plus 828 to serve a shower and a bath.
All the old pipe work from the old conventional system is still insitu
just blanked off. Frankly the combi is just poor; baths are just not
worth having and the shower flow is disturbed so much by washing
machines, dishwashers etc.I thought I could get away with it because we
all know students dont wash but this lot do....

I have read what you all say about combis but think that they are
useless for more than one old lady in a flat, I am afraid.

We now want to put in a an en suite shower room on the second floor,
exactly where the old airing cupboard/immersion heater was. The boiler
is on the ground floor in the kitchen and the existing bathroom is on
first floor.

I want to put a megaflow or similar unvented storage with an upgraded
new boiler.

The vaillant is nearly new and I wonder if some clever internal
rearrangement will turn it into a sealed system boiler or should I just
bite the bullet and buy a new proper one.

What do you reckon?


You could pension off the combi into just feeding part of the
requirement such as washbasins or sinks perhaps - depending on the
plumbing arrangements.

You can then use the CH part of the combi in the same way as any other
boiler to provide heat for the cylinder's heating coil. This
requires a diverter valve, thermostat and possibly a timer/programmer.
No big deal and nothing lost.

Before you do this, however, do check the cold mains flow rate and
pressure and make sure that they are adequate. Typically a combi has
poor performance when its power rating is inadequate for the
requirement - simple physics of heat transfer. However, if the water
flow rate is also low, then a pressurised cylinder wouldn't help and
you would need to use a system with roof supply tank.






--

..andy

To email, substitute .nospam with .gl

Frankly the combi is just poor; baths are just not worth having
and the shower flow is disturbed so much by washing machines,
dishwashers etc.

You can (and probably should these days) run off cold fill only.

The vaillant is nearly new and I wonder if some clever internal
rearrangement will turn it into a sealed system boiler or should I just
bite the bullet and buy a new proper one.

No problem whatsoever. A combi boiler is just as capable as any other of
heating a water cylinder.

Christian.

"richman" wrote in message
oups.com...

We converted a five bed house in London for students and the plumber
put in a gas Vaillant turbomax plus 828 to serve a shower and a bath.
All the old pipe work from the old conventional system is still insitu
just blanked off. Frankly the combi is just poor; baths are just not
worth having and the shower flow is disturbed so much by washing
machines, dishwashers etc.I thought I could get away with it because we
all know students dont wash but this lot do....

I have read what you all say about combis but think that they are
useless for more than one old lady in a flat, I am afraid.

I'm afraid you and your "plumber", so not know much about combi's. :-)
High flow models are available; I doubt if he has seen one. This sounds a
typical cheapo landlords effort to me. Well firstly I would have properly
assessed the DHW demand. How many people are using this house? Why a bath,
when students only need a shower? A bath takes space and somthing else to
maintain and keep clean.

There are high flowrate combi's around and I would have gone for one of
those. Also I would have arranged the pipework properly. This sounds like
15mm cold water mains pipe snaking around the house and all appliances teed
off this, of which the combi is one. The combi, ideally should have it own
dedicated cold supply from the stop cock, with the cold supply to the shower
taken off this combi supply just before the combi inlet. This way when a
toilet is flushed it doesn't affect the combi DHW.

We now want to put in a an en suite
shower room on the second floor,
exactly where the old airing cupboard/immersion
heater was. The boiler is on the ground floor
in the kitchen and the existing bathroom is on
first floor.

I want to put a megaflow or similar
unvented storage with an upgraded
new boiler.

The same applies to an unvented cylinder regarding the pipework. A 22mm
supply pipe back to the stop cock. Go for a low pressure heat bank rather
than an unvented cylinder. No explosions, and students can do silly things
when drunk, like ****ing about with the cylinder controls.

The vaillant is nearly new and I wonder if some clever internal
rearrangement will turn it into a sealed system boiler or should I just
bite the bullet and buy a new proper one.

What do you reckon?

The Vaillant can be turned into a system boiler. That is easy as that is
what it is with a DHW section added.

CH demands? CH zoned? If not is it better to have separte timed zones? A
mains pressure system: combi, unvented, heat bank, is dependent on the flow
and pressure of the mains

Start at the beginning. Give me your DHW demands: number of people in the
house, Number of showers, sinks, size of cold water mains, idea of flowrate,
etc.

Christian McArdle wrote:

Frankly the combi is just poor; baths are just not worth having
and the shower flow is disturbed so much by washing machines,
dishwashers etc.


You can (and probably should these days) run off cold fill only.

Probably better for the clothes / dishes as well these days (modern
detergents and all that). Note though that even cold fill only can still
knacker a shower in some cases. If you mains flow is marginal, turning
on a cold tap will reduce the available flow to the combi causing a
temperature rise in its output.


--
Cheers,

John.

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

Note though that even cold fill only can still knacker a shower
in some cases. If you mains flow is marginal, turning on a cold
tap will reduce the available flow to the combi causing a
temperature rise in its output.

If it is that marginal, then a mains pressure cylinder/heat bank, would
suffer the same effect as a combi, too.

Christian.

"John Rumm" wrote in message
...
Christian McArdle wrote:

Frankly the combi is just poor; baths are just not worth having
and the shower flow is disturbed so much by washing machines,
dishwashers etc.


You can (and probably should these days) run off cold fill only.

Probably better for the clothes / dishes as well these days (modern
detergents and all that). Note though that even cold fill only can still
knacker a shower in some cases. If you mains flow is marginal, turning
on a cold tap will reduce the available flow to the combi causing a
temperature rise in its output.

Depends on how it is piped up. And if still a problem you get a proper
combi shower mixer with integral pressure balancer, or fit an external one
on the hot and cold to the shower.

The w/machine and dishwasher can be piped up to take cold only. In reality
the amount of hot water taken from the DHW system is negligible, as most of
the water taken is cold via the DHW dead-leg pipe. Bt the time hot comes
through the appliance is near full of water anyway.

If you have a secondary circulation loop then a hot fill can save money in
energy.

In this case, the OP would be better sorting out the pipework, getting the
combi supply dedicated back to the stop cock and piped up as I suggested,
get the appliances on cold fill, get rid of the bath, have a flow restrictor
on the sink tap (available from BES), and put in another combi for the new
ensuite. This is "probably" the most cost effective route for him. I await
his DHW demands.

In this case, the OP would be better sorting out the pipework, getting the
combi supply dedicated back to the stop cock and piped up as I suggested,
get the appliances on cold fill, get rid of the bath, have a flow restrictor
on the sink tap (available from BES), and put in another combi for the new
ensuite. This is "probably" the most cost effective route for him. I await
his DHW demands.

I was wondering when a second combi would come into the discussion

"Christian McArdle" wrote in message
. net...
Note though that even cold fill only can still knacker a shower
in some cases. If you mains flow is marginal, turning on a cold
tap will reduce the available flow to the combi causing a
temperature rise in its output.

If it is that marginal, then a mains pressure cylinder/heat bank, would
suffer the same effect as a combi, too.

Exactly. More thought is generally given to unvented cylinder and heat bank
installations. Far too many combi's are just slapped in teeing off the
nearest cold mains pipe for its supply, giving them a poor reputation.

On Thu, 4 Aug 2005 12:22:13 +0100, "Doctor Drivel"
wrote:


"John Rumm" wrote in message
...
Christian McArdle wrote:

Frankly the combi is just poor; baths are just not worth having
and the shower flow is disturbed so much by washing machines,
dishwashers etc.


You can (and probably should these days) run off cold fill only.

Probably better for the clothes / dishes as well these days (modern
detergents and all that). Note though that even cold fill only can still
knacker a shower in some cases. If you mains flow is marginal, turning
on a cold tap will reduce the available flow to the combi causing a
temperature rise in its output.

Depends on how it is piped up. And if still a problem you get a proper
combi shower mixer with integral pressure balancer, or fit an external one
on the hot and cold to the shower.

The w/machine and dishwasher can be piped up to take cold only. In reality
the amount of hot water taken from the DHW system is negligible, as most of
the water taken is cold via the DHW dead-leg pipe. Bt the time hot comes
through the appliance is near full of water anyway.

If you have a secondary circulation loop then a hot fill can save money in
energy.


Unnecessary expense and would take a very long time to recover the
cost considering that dishwashers and detergents used in them are
designed for cold fill and gradual heating, and washing machines,
detergents and clothes are also mainly warm wash only these days.


In this case, the OP would be better sorting out the pipework, getting the
combi supply dedicated back to the stop cock and piped up as I suggested,
get the appliances on cold fill, get rid of the bath, have a flow restrictor
on the sink tap (available from BES), and put in another combi for the new
ensuite. This is "probably" the most cost effective route for him. I await
his DHW demands.


In other words alter the requirements to meet the limitations of the
combi. This was not what was being requested.



--

..andy

To email, substitute .nospam with .gl

On Thu, 04 Aug 2005 12:33:05 +0100, Andy Hall
wrote:

Unnecessary expense and would take a very long time to recover the
cost considering that dishwashers and detergents used in them are
designed for cold fill and gradual heating, and washing machines,
detergents and clothes are also mainly warm wash only these days.


My dishwasher has only a cold inlet. Certain proteins harden when
"cooked", so you wouldn't want to bake them on. (egg for example).

Washing machines may be warm wash only these days, but unfortunately
food is much more colourful than it used to be. So if saturday night's
popadoms somehow managed to eject some lime pickle onto your pure
white shirt, you're going to have problems if you wash it at 40C! That
kind of stain needs a minimum of two washes (or some sort of
non-chlorine based bleaching agent) at modern temperatures.

Mr F

"Doctor Drivel" wrote in message
eenews.net...

"richman" wrote in message
oups.com...

We converted a five bed house in London for students and the plumber
put in a gas Vaillant turbomax plus 828 to serve a shower and a bath.
All the old pipe work from the old conventional system is still insitu
just blanked off. Frankly the combi is just poor; baths are just not
worth having and the shower flow is disturbed so much by washing
machines, dishwashers etc.I thought I could get away with it because we
all know students dont wash but this lot do....

I have read what you all say about combis but think that they are
useless for more than one old lady in a flat, I am afraid.

I'm afraid you and your "plumber", so not know much about combi's. :-)
High flow models are available; I doubt if he has seen one. This sounds a
typical cheapo landlords effort to me. Well firstly I would have properly
assessed the DHW demand. How many people are using this house? Why a
bath,
when students only need a shower? A bath takes space and somthing else to
maintain and keep clean.

There are high flowrate combi's around and I would have gone for one of
those. Also I would have arranged the pipework properly. This sounds
like
15mm cold water mains pipe snaking around the house and all appliances
teed
off this, of which the combi is one. The combi, ideally should have it
own
dedicated cold supply from the stop cock, with the cold supply to the
shower
taken off this combi supply just before the combi inlet. This way when a
toilet is flushed it doesn't affect the combi DHW.

We now want to put in a an en suite
shower room on the second floor,
exactly where the old airing cupboard/immersion
heater was. The boiler is on the ground floor
in the kitchen and the existing bathroom is on
first floor.

I want to put a megaflow or similar
unvented storage with an upgraded
new boiler.

The same applies to an unvented cylinder regarding the pipework. A 22mm
supply pipe back to the stop cock. Go for a low pressure heat bank rather
than an unvented cylinder. No explosions, and students can do silly
things
when drunk, like ****ing about with the cylinder controls.

The vaillant is nearly new and I wonder if some clever internal
rearrangement will turn it into a sealed system boiler or should I just
bite the bullet and buy a new proper one.

What do you reckon?

The Vaillant can be turned into a system boiler. That is easy as that is
what it is with a DHW section added.

CH demands? CH zoned? If not is it better to have separte timed zones? A
mains pressure system: combi, unvented, heat bank, is dependent on the
flow
and pressure of the mains

Start at the beginning. Give me your DHW demands: number of people in the
house, Number of showers, sinks, size of cold water mains, idea of
flowrate,
etc.



The Vaillant Turbomax 828 can deliver 11ltrs/min wth a temperature rise of
30C.
It'll run a shower easily, and a bath in less than 10minutes.

As others have stated, perhaps your pipework is not very good. Test it by
seeing what
the cold bath tap will deliver at full whack, or even the kitchen cold tap.
It should be
considerably more than 11litres/min to give you some margin. My cold water
taps
can deliver 19litres/min. Even so, a pressure equalisation valve will help
stop slugs
of cold water coming through a shower in a house wih so many people in it.

Andy.

"Richard Conway" wrote in message
...

In this case, the OP would be better sorting out the pipework, getting
the
combi supply dedicated back to the stop cock and piped up as I
suggested,
get the appliances on cold fill, get rid of the bath, have a flow
restrictor
on the sink tap (available from BES), and put in another combi for the
new
ensuite. This is "probably" the most cost effective route for him. I
await
his DHW demands.

I was wondering when a second combi would come into the discussion

It may be the best solution for him, as it is for many homes. Have you
anything constructive to add?

"Andy Hall" wrote in message
...
On Thu, 4 Aug 2005 12:22:13 +0100, "Doctor Drivel"
wrote:


"John Rumm" wrote in message
...
Christian McArdle wrote:

Frankly the combi is just poor; baths are just not worth having
and the shower flow is disturbed so much by washing machines,
dishwashers etc.


You can (and probably should these days) run off cold fill only.

Probably better for the clothes / dishes as well these days (modern
detergents and all that). Note though that even cold fill only can
still
knacker a shower in some cases. If you mains flow is marginal, turning
on a cold tap will reduce the available flow to the combi causing a
temperature rise in its output.

Depends on how it is piped up. And if still a problem you get a proper
combi shower mixer with integral pressure balancer, or fit an external
one
on the hot and cold to the shower.

The w/machine and dishwasher can be piped up to take cold only. In
reality
the amount of hot water taken from the DHW system is negligible, as most
of
the water taken is cold via the DHW dead-leg pipe. Bt the time hot comes
through the appliance is near full of water anyway.

If you have a secondary circulation loop then a hot fill can save money
in
energy.

Unnecessary expense

A secondary circulation pump can also save much money in reduced water
waste. Also it is a great convenience to have hot water immediately at the
taps in any water system.

In this case, the OP would be better sorting out the pipework, getting
the
combi supply dedicated back to the stop cock and piped up as I suggested,
get the appliances on cold fill, get rid of the bath, have a flow
restrictor
on the sink tap (available from BES), and put in another combi for the
new
ensuite. This is "probably" the most cost effective route for him. I
await
his DHW demands.

In other words alter the requirements to meet the limitations of the
combi. This was not what was being requested.

Nope. Fit the combi properly. The same will apply to any water system; fit
it properly. It is clear this combi was just slapped in. Boy do you have a
strange logic. Must be Little Middle England logic.

Doctor Drivel wrote:
"Richard Conway" wrote in message
...


In this case, the OP would be better sorting out the pipework, getting

the

combi supply dedicated back to the stop cock and piped up as I

suggested,

get the appliances on cold fill, get rid of the bath, have a flow

restrictor

on the sink tap (available from BES), and put in another combi for the

new

ensuite. This is "probably" the most cost effective route for him. I

await

his DHW demands.

I was wondering when a second combi would come into the discussion


It may be the best solution for him, as it is for many homes. Have you
anything constructive to add?


Not really, no

"Richard Conway" wrote in message
...
Doctor Drivel wrote:
"Richard Conway" wrote in message
...


In this case, the OP would be better sorting out the pipework, getting

the

combi supply dedicated back to the stop cock and piped up as I

suggested,

get the appliances on cold fill, get rid of the bath, have a flow

restrictor

on the sink tap (available from BES), and put in another combi for the

new

ensuite. This is "probably" the most cost effective route for him. I

await

his DHW demands.

I was wondering when a second combi would come into the discussion


It may be the best solution for him, as it is for many homes. Have you
anything constructive to add?

Not really, no

Then no need to clutter the thread.

On Thu, 4 Aug 2005 13:15:07 +0100, "Doctor Drivel"
wrote:


If you have a secondary circulation loop then a hot fill can save money
in
energy.

Unnecessary expense

A secondary circulation pump can also save much money in reduced water
waste. Also it is a great convenience to have hot water immediately at the
taps in any water system.

A couple of litres? Are you serious?



In this case, the OP would be better sorting out the pipework, getting
the
combi supply dedicated back to the stop cock and piped up as I suggested,
get the appliances on cold fill, get rid of the bath, have a flow
restrictor
on the sink tap (available from BES), and put in another combi for the
new
ensuite. This is "probably" the most cost effective route for him. I
await
his DHW demands.

In other words alter the requirements to meet the limitations of the
combi. This was not what was being requested.

Nope. Fit the combi properly. The same will apply to any water system; fit
it properly. It is clear this combi was just slapped in.

Even if it were running perfectly with unlimited supply of water it
would still be inadequate since this is an 11 litre/min boiler.




--

..andy

To email, substitute .nospam with .gl

On Thu, 4 Aug 2005 12:55:26 +0100, "andrewpreece"
wrote:





The Vaillant Turbomax 828 can deliver 11ltrs/min wth a temperature rise of
30C.
It'll run a shower easily, and a bath in less than 10minutes.

In the winter, 11lpm would take at least 15 mins to fill a bath and
would provide a marginal shower.



--

..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Thu, 4 Aug 2005 13:15:07 +0100, "Doctor Drivel"
wrote:


If you have a secondary circulation loop then a hot fill can save
money
in
energy.

Unnecessary expense

A secondary circulation pump can also save much money in reduced water
waste. Also it is a great convenience to have hot water immediately at
the
taps in any water system.

A couple of litres? Are you serious?

??

In this case, the OP would be better sorting out the pipework, getting
the
combi supply dedicated back to the stop cock and piped up as I
suggested,
get the appliances on cold fill, get rid of the bath, have a flow
restrictor
on the sink tap (available from BES), and put in another combi for the
new
ensuite. This is "probably" the most cost effective route for him. I
await
his DHW demands.

In other words alter the requirements to meet the limitations of the
combi. This was not what was being requested.

Nope. Fit the combi properly. The same will apply to any water system;
fit
it properly. It is clear this combi was just slapped in.

Even if it were running perfectly with unlimited supply of water it
would still be inadequate since this is an 11 litre/min boiler.

That is one issue, the main one in this case. Another is priority of water.
The system should be piped to ensure the shower has little, to no,
interference from other draw-offs.

"Andy Hall" wrote in message
...
On Thu, 4 Aug 2005 12:55:26 +0100, "andrewpreece"
wrote:

The Vaillant Turbomax 828 can deliver 11ltrs/min wth a temperature rise
of
30C.
It'll run a shower easily, and a bath in less than 10minutes.

In the winter, 11lpm would take at least 15 mins to fill a bath and
would provide a marginal shower.

Total tripe. 11 l/min @35C temp rise. At 5C mains temp, it will deliver
about 9 to 9.5 litres/min at 45C (shower temp), that is just the hot water
flow. 9 litres/min is more than fine, and "nowhere" near marginal, and
about 2 l/min over recommendations.

Phew....

I left my message, went down the pub, watched a bit of cricket, came
back to the computer and find all your replies. Thanks a lot certainly
a quicker response than the Vaillant helpline.

Anyway, firstly I admit that I'm not a plumber (nor a "cheapo
landlord")but am a reasonably seasoned diy-er. I used to do bits of
plumbing until I had to get a corgi to do everything and I used to do
electrics before I had to ask the building inspector how to wire a
plug.

Anyway, I left this system to a qualified corgi plumber(he said) who
fully assessed the relevant dhw and ch requirements (I even have a bit
of paper to prove it) to allow for a family of four or five, requiring
hw for shower, bath and basin, sink, dw and wm. He concluded the
turbomax 828 was ok with over 100000 btu and need for showers made
combi best. The fact that he had a cheap one left over from the last
job would not have been on his mind.

The cold water incoming flow is ok/very good although it does have
appliances etc teed off it so we could work on rearranging and upgrade
pipe to 22mm. Dedicated feed for boiler back to the stop cock would be
easy.

Despite what Dr Drivel says I cannot be convinced that a combi is
right. Even a high flow rate one (whatever that is?)

I didn't ask to have the bath removed nor do I want all the hassle of
taking a new gas supply three floors up the house together with flue
etc (not outside wall). If I'm not keen on one combi I'm hardly
likely to want two am I?

No surely the best bet is new system boiler wall hung where the
existing is (with improved pipework) and some sort of storage as much
as possible (200l) (megaflow/vantage etc)to give equal pressure all
round the house utilising existing pipework already there. In other
words admit we got it wrong on the spec first time!

Anyone want a nearly new Vaillant 828 combi (Highbury north London)
otherwise its ebay

On Thu, 4 Aug 2005 15:13:16 +0100, "Doctor Drivel"
wrote:


"Andy Hall" wrote in message
.. .
On Thu, 4 Aug 2005 12:55:26 +0100, "andrewpreece"
wrote:

The Vaillant Turbomax 828 can deliver 11ltrs/min wth a temperature rise
of
30C.
It'll run a shower easily, and a bath in less than 10minutes.

In the winter, 11lpm would take at least 15 mins to fill a bath and
would provide a marginal shower.

Total tripe. 11 l/min @35C temp rise. At 5C mains temp, it will deliver
about 9 to 9.5 litres/min at 45C (shower temp), that is just the hot water
flow. 9 litres/min is more than fine, and "nowhere" near marginal, and
about 2 l/min over recommendations.

If you read what you just wrote, you will realise that you have
written tripe.

If 45 degrees is shower temp, then it would be the *only* flow - you
wouldn't be adding cold to it if that is the usage temperature.

9 litres/min is **** poor and not a great deal more than an electric
shower.

To top it all, you are advocating that the poor students make do with
this rather than being able to have a bath.

That's where we came in. It's inadequate and you are trying to make a
case that it is adequate. Nonsense.

The film has been running for a couple of hours and it's almost time
for the ice cream lady to come round.




--

..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Thu, 4 Aug 2005 15:13:16 +0100, "Doctor Drivel"
wrote:


"Andy Hall" wrote in message
.. .
On Thu, 4 Aug 2005 12:55:26 +0100, "andrewpreece"
wrote:

The Vaillant Turbomax 828 can deliver 11ltrs/min wth a temperature
rise
of
30C.
It'll run a shower easily, and a bath in less than 10minutes.

In the winter, 11lpm would take at least 15 mins to fill a bath and
would provide a marginal shower.

Total tripe. 11 l/min @35C temp rise. At 5C mains temp, it will deliver
about 9 to 9.5 litres/min at 45C (shower temp), that is just the hot
water
flow. 9 litres/min is more than fine, and "nowhere" near marginal, and
about 2 l/min over recommendations.

If you read what you just wrote, you will realise that you have
written tripe.

...let's see what his conclusions are.....

If 45 degrees is shower temp, then
it would be the *only* flow - you
wouldn't be adding cold to it if that is
the usage temperature.

9 litres/min is **** poor

Nonsense. The recommended is 7 to 7.5 litres. 9 to 10 is more than
adequate. It is the strong pressure on the skin that people want, not
masses of needless wasteful flow. That is the worst case example, while
right now at about 18C mains water temp it will deliver far more.

and not a great deal more than an electric
shower.

Tripe. Electric are **** poor; 9 l/min is about the best you will get and
they cost.

To top it all, you are advocating
that the poor students make do with
this rather than being able to have a bath.

A normal 11 l/min combi delivers an excellent shower all year around.

snip babble

In article , Andy Hall
wrote:
9 litres/min is **** poor and not a great deal more than an electric
shower.

Sorry Andy but unless there's a bit of physics missing me, for the same
temperature a 28kW combi is going to deliver 3 times the flow of a
9.5kW electric shower. Three times is a lot more than "not a great deal
more". My 24kW combi delivers a vastly better shower than the gravity
fed Mira 8 that preceded it.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm
[Latest version QSEDBUK 1.10 released 4 April 2005]

Doctor Drivel wrote:

Exactly. More thought is generally given to unvented cylinder and heat bank
installations. Far too many combi's are just slapped in teeing off the
nearest cold mains pipe for its supply, giving them a poor reputation.

That, and many people fit tiddly little 24kW toy ones.

--
Cheers,

John.

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

richman wrote:

Anyway, I left this system to a qualified corgi plumber(he said) who
fully assessed the relevant dhw and ch requirements (I even have a bit
of paper to prove it) to allow for a family of four or five, requiring
hw for shower, bath and basin, sink, dw and wm.

I'd say there's a big difference between the requirements of a family of
5 and a housefull of 5 students. In a family, there are likely to be
kids needing a tub at 7pm, or older ones who can be told (with luck) to
have their shower or bath in the evening to avoid clogging up the
bathroom for mum and dad in the morning. With the students, you have 5
adults, all doing the same thing and without the 'pecking order' of the
family, and they are all likely will want a shower or bath at exactly
the same time of day.

David

On Thu, 4 Aug 2005 17:51:51 +0100, "Doctor Drivel"
wrote:


"Andy Hall" wrote in message

If 45 degrees is shower temp, then
it would be the *only* flow - you
wouldn't be adding cold to it if that is
the usage temperature.

9 litres/min is **** poor

Nonsense. The recommended is 7 to 7.5 litres.

Recommended by whom?

9 to 10 is more than
adequate.

Says who?

It is the strong pressure on the skin that people want, not
masses of needless wasteful flow.

Says who?

That is the worst case example, while
right now at about 18C mains water temp it will deliver far more.

Irrelevant. A system should always be designed for the worst case or
close to it.



and not a great deal more than an electric
shower.

Tripe. Electric are **** poor; 9 l/min is about the best you will get and
they cost.


So if 9lpm is **** poor, why are you saying that it's OK of delivered
by a combi rather than an electric shower? Do they have an
attachment to dispense Holy Water or something?



To top it all, you are advocating
that the poor students make do with
this rather than being able to have a bath.

A normal 11 l/min combi delivers an excellent shower all year around.


If you have low enough expectations of the word "excellent"


--

..andy

To email, substitute .nospam with .gl

On Thu, 04 Aug 2005 18:09:09 +0100, Tony Bryer
wrote:

In article , Andy Hall
wrote:
9 litres/min is **** poor and not a great deal more than an electric
shower.

Sorry Andy but unless there's a bit of physics missing me, for the same
temperature a 28kW combi is going to deliver 3 times the flow of a
9.5kW electric shower. Three times is a lot more than "not a great deal
more". My 24kW combi delivers a vastly better shower than the gravity
fed Mira 8 that preceded it.


Yes of course, but in comparison with 15-20lpm from a storage system
both are limited.



--

..andy

To email, substitute .nospam with .gl

richman wrote:
Despite what Dr Drivel says I cannot be convinced that a combi is
right. Even a high flow rate one (whatever that is?) ...
No surely the best bet is new system boiler wall hung where the
existing is (with improved pipework) and some sort of storage as much
as possible (200l) (megaflow/vantage etc)to give equal pressure all
round the house utilising existing pipework already there. In other
words admit we got it wrong on the spec first time!
Anyone want a nearly new Vaillant 828 combi (Highbury north London)
otherwise its ebay

Why not keep the existing combi and add a cylinder to the central
heating side, as has been suggested.

That way you have the best of both worlds - unlimited trickle of instant
tepid water from the combi side, and stored hot water after a little
wait on the cylinder side.

A win win situation without using two combis and, if you use a heatbank
rather than a mains pressure cylinder, you can DIY it and won't need an
annual safety certificate on a pressurised cylinder.

Owain

"Andy Hall" wrote in message
...
On Thu, 4 Aug 2005 17:51:51 +0100, "Doctor Drivel"
wrote:


"Andy Hall" wrote in message

If 45 degrees is shower temp, then
it would be the *only* flow - you
wouldn't be adding cold to it if that is
the usage temperature.

9 litres/min is **** poor

Nonsense. The recommended is 7 to 7.5 litres.

Recommended by whom?

9 to 10 is more than
adequate.

Says who?

Many millions throughout the world.

It is the strong pressure on the skin that people want, not
masses of needless wasteful flow.

Says who?

That is the worst case example, while
right now at about 18C mains water temp it will deliver far more.

Irrelevant. A system should always
be designed for the worst case or
close to it.

They are, and cope well then.

and not a great deal more than an electric
shower.

Tripe. Electric are **** poor; 9 l/min is about the best you will get
and
they cost.

So if 9lpm is **** poor,

That is the best they can do at the best case scenario. In the worst case 7
at most.

To top it all, you are advocating
that the poor students make do with
this rather than being able to have a bath.

A normal 11 l/min combi delivers an excellent shower all year around.

If you have low enough expectations of the word "excellent"

That is a silly comment expected from someone who drives around a filthy
diesel 4x4 with the aerodynamics of a brick. You are a mobile global
warming enhancing pollution machine. Waste for the sake of waste.

"Andy Hall" wrote in message
...
On Thu, 04 Aug 2005 18:09:09 +0100, Tony Bryer
wrote:

In article , Andy Hall
wrote:
9 litres/min is **** poor and not a great deal more than an electric
shower.

Sorry Andy but unless there's a bit of physics missing me, for the same
temperature a 28kW combi is going to deliver 3 times the flow of a
9.5kW electric shower. Three times is a lot more than "not a great deal
more". My 24kW combi delivers a vastly better shower than the gravity
fed Mira 8 that preceded it.

Yes of course, but in comparison with 15-20lpm from a storage system
both are limited.

That is not the point in question here. It is your "not a great deal more"
electric /combi misparrison.

20 litres/min is irresponsible. People want the high pressure against the
skin not volume.

"John Rumm" wrote in message
...
Doctor Drivel wrote:

Exactly. More thought is generally given to unvented cylinder and heat
bank
installations. Far too many combi's are just slapped in teeing off the
nearest cold mains pipe for its supply, giving them a poor reputation.

That, and many people fit tiddly little 24kW toy ones.

What you wrote was very sensible.

"richman" wrote in message
oups.com...

Phew....

I left my message, went down the pub, watched a bit of cricket, came
back to the computer and find all your replies. Thanks a lot certainly
a quicker response than the Vaillant helpline.

Anyway, firstly I admit that I'm not a plumber (nor a "cheapo
landlord")but am a reasonably seasoned diy-er. I used to do bits of
plumbing until I had to get a corgi to do everything and I used to do
electrics before I had to ask the building inspector how to wire a
plug.

Anyway, I left this system to a qualified corgi plumber(he said) who
fully assessed the relevant dhw and ch requirements (I even have a bit
of paper to prove it) to allow for a family of four or five, requiring
hw for shower, bath and basin, sink, dw and wm. He concluded the
turbomax 828 was ok with over 100000 btu and need for showers made
combi best. The fact that he had a cheap one left over from the last
job would not have been on his mind.

The combi flowrate is clearly unsuitable for the demands.

The cold water incoming flow is ok/very good although it does have
appliances etc teed off it so we could work on rearranging and upgrade
pipe to 22mm. Dedicated feed for boiler back to the stop cock would be
easy.

Despite what Dr Drivel says I cannot be convinced that a combi is
right. Even a high flow rate one (whatever that is?)

High flowrate is what is says. Yours is 11/litres min flowrate. A high one
will be 20 litres/min and above. In short about twice what you have, and
will fill bath in no time, and do 2 to 3 showers simultaneously..

I didn't ask to have the bath
removed

You didn't, but why have one with a bunch of young students - who will not
clean it anyway. It only puts pressure on the DHW system.

nor do I want all the hassle of
taking a new gas supply three floors up the house together with flue
etc (not outside wall). If I'm not keen on one combi I'm hardly
likely to want two am I?

You don't like this combi, which is a very good one, because it was
misapplied.

No surely the best bet is new system boiler wall hung where the
existing is (with improved pipework) and some sort of storage as much
as possible (200l) (megaflow/vantage etc)to give equal pressure all
round the house utilising existing pipework already there. In other
words admit we got it wrong on the spec first time!

Anyone want a nearly new Vaillant 828 combi (Highbury north London)
otherwise its ebay

The 828 "is" a system boiler. All you need do is not connect up the water
section.

Keep an open mind, Two approaches for you. Take heed.

1. Keep the 828. Have the DHW of this, supply, the kitchen tap, the dw and
w/m. Then fit a high flowrate Rinnai multi-point water heater than can fill
a bath pronto and do two showers. A multi-point only heats hot water - no
CH from this. Have the Rinnai supply the showers, bath and bathroom basins.
You have now divided rule.

Rinnai have a model that can be fitted "outside", so no fluing problems. It
has built-in frost protection.
http://www.discountedheating.co.uk/s...r_Heaters.html
You need continuous DHW with 4 people around. That is you never run out of
DHW. This is a simple and cost effective approach, and no space taken up
by a cylinder or 3-way valves, etc.

Just find a suitable location, run a gas pipe, supply pipe and DHW draw-off
pipe. This way if one of the DHW heating appliances is down the other still
works, so less pressure on you in case of breakdowns, as always DHW
somewhere in the house.

Have dedicated 22mm supplies to the combi and multi-point. The Rinnai is
made in Japan and is very reliable. One of the biggest selling instant
heaters in the world. Rinnai are the world's largest gas appliance maker.

2. Use the 828 as system boiler, "but" have it supply only the one shower
on the DHW side. Fit a heat bank, or Megaflow, preferably a heat bank, and
have this do all the rest of the DHW. Once again it has its own dedicated
supply pipe. The heat bank or megaflow will need a 3-way valve, etc as per
a normal heating system, so more complexity.

What other gas appliances are there?

I would go for the Rinnai solution, as you have backup, never run out of hot
water, flexible in location (even outside), no space taken up by a cylinder,
cheaper, etc.

"Owain" wrote in message
...
richman wrote:
Despite what Dr Drivel says I cannot be convinced that a combi is
right. Even a high flow rate one (whatever that is?) ...
No surely the best bet is new system boiler wall hung where the
existing is (with improved pipework) and some sort of storage as much
as possible (200l) (megaflow/vantage etc)to give equal pressure all
round the house utilising existing pipework already there. In other
words admit we got it wrong on the spec first time!
Anyone want a nearly new Vaillant 828 combi (Highbury north London)
otherwise its ebay

Why not keep the existing combi and add a cylinder to the central
heating side, as has been suggested.

That way you have the best of both worlds - unlimited trickle of instant
tepid water from the combi side,

Don't be so pathetic!!! The mans is after constructive advise, not Jocko
stupidity.

On Thu, 4 Aug 2005 20:07:09 +0100, "Doctor Drivel"
wrote:

.

20 litres/min is irresponsible. People want the high pressure against the
skin not volume.


Which people?



--

..andy

To email, substitute .nospam with .gl

richman wrote:

The cold water incoming flow is ok/very good although it does have
appliances etc teed off it so we could work on rearranging and upgrade
pipe to 22mm. Dedicated feed for boiler back to the stop cock would be
easy.

Assuming that your flow rate is ok (i.e. = 20l/m) then you have plenty
of options. Although it might be worth estimating what your worst case
water demand is going to be. If it exceeds the mains capacity then you
are either going to need to make use of stored water (i.e. loft cistern,
or mains pressure accumulator), or go for a mains upgrade.

Despite what Dr Drivel says I cannot be convinced that a combi is
right. Even a high flow rate one (whatever that is?)

Using the model you have to supply all hot water on an "instantaneous"
basis is obviously not a good solution - it is way short of power to do
that.

No surely the best bet is new system boiler wall hung where the
existing is (with improved pipework) and some sort of storage as much
as possible (200l) (megaflow/vantage etc)to give equal pressure all
round the house utilising existing pipework already there. In other
words admit we got it wrong on the spec first time!

I would suggest that you keep the existing boiler (since it is a good
one), and re-plumb things to use it mostly as a system boiler. I would
probably take the DHW output from it to feed one shower or perhaps the
kitchen, and then plumb everything else to be fed from the stored hot
water system. (unvented / heatbank or whatever you want)


--
Cheers,

John.

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

"Andy Hall" wrote in message
...
On Thu, 4 Aug 2005 20:07:09 +0100, "Doctor Drivel"
wrote:

20 litres/min is irresponsible. People want the high pressure against
the
skin not volume.

Which people?

Normal people.

In message ws.net,
Doctor Drivel writes

I was wondering when a second combi would come into the discussion


It may be the best solution for him, as it is for many homes. Have you
anything constructive to add?

Not really, no

Then no need to clutter the thread.


Ha ha

--
geoff

On Thu, 4 Aug 2005 22:33:54 +0100, "Doctor Drivel"
wrote:


"Andy Hall" wrote in message
.. .
On Thu, 4 Aug 2005 20:07:09 +0100, "Doctor Drivel"
wrote:

20 litres/min is irresponsible. People want the high pressure against
the
skin not volume.

Which people?

Normal people.


Ah... How would you know then?




--

..andy

To email, substitute .nospam with .gl