Boiler options
 

Hey all,

Time to access your boundless wisdom again!

We're considering options for replacing our current ch/dhw system. We
currently have a gas-fired boiler and tank with a pathetic (7.5kW)
electric shower. The tank is shoe-horned into a small cupboard at
floor level in the loft-conversion, at pretty much the same height as
the bathroom, with the header tank in what's left of the loft - maybe
2m higher. We seem to have the worst of all worlds: a *truly* pathetic
shower, a bath that takes 15 minutes to fill, a
not-desperately-efficient boiler and wasted energy from the hot-water
tank (which isn't well insulated).

I've had a bit of a look, using this site and the FAQs, at the
alternatives, and it seems to me that what we want is a combi. I need
to test the mains flow rate (seems pretty good, though), but as we
only have a single bathroom and there is not going to be any need to
run baths concurrently with showering (plus, we aren't that fussed
about slow bath-running) it seems a heatbank arrangement is overkill.
There are only two of us with no plans for expansion at the moment.
What are your thoughts?

One of our greatest concerns is the efficiency of the new arrangement
- ignoring, for the moment, the environmental impact of chucking out
all the old stuff and replacing it. With the inefficiency of our
current system, I guess we'll start saving pretty quickly...

I've checked the SEBDUK database and got the list of 50 most efficient
boilers - we'll probably select the most suitable from that list. Can
anyone give any extra insight into particularly suitable models?

Thanks again in advance for you help!

Adam...

I've checked the SEBDUK database and got the list of 50 most efficient
boilers - we'll probably select the most suitable from that list. Can
anyone give any extra insight into particularly suitable models?

You don't give a budget. Assuming you want a well regarded midrange model
rather than a cheapie, the Worcester-Bosch Greenstar Highflow 440, recently
discussed might be appropriate. It will provide a good shower and still
manage to fill a bath before Christmas, if not at the rate of a heat bank,
unvented cylinder or pumped gravity system.

It uses a small internal heat store to give enough reasonable flow to mostly
fill your bath (depending on size) before cutting back to 11 litres a
minute, which it can maintain indefinately. 11 lpm at mains pressure is
enough for a decent power shower, but not a wide bore low pressure drencher
type, or a panel type with body jets.

If you prefer a high flow instantaneous combi (probably more appropriate for
a drencher shower), then there Bosch-Worcester have Greenstar versions up to
40kW.

Christian.

If you prefer a high flow instantaneous combi (probably more appropriate
for
a drencher shower), then there Bosch-Worcester have Greenstar versions up
to
40kW.

P.S. to compare with your electric shower, it is perfectly reasonable to
suppose that the increased potential flow rate will be proportional to the
rating in kW.

A 40kW combi will produce over 5 times the shower flow of your electric
shower. A really basic 24kW combi will produce over 3 times as much, which
will be enough to make the shower really quite pleasant, if the shower head
is chosen wisely.

Christian.

"Christian McArdle" wrote in message
. net...

I've checked the SEBDUK database
and got the list of 50 most efficient
boilers - we'll probably select the most
suitable from that list. Can
anyone give any extra insight into particularly
suitable models?

You don't give a budget. Assuming you want
a well regarded midrange model
rather than a cheapie, the Worcester-Bosch
Greenstar Highflow 440, recently
discussed might be appropriate. It will provide
a good shower and still manage to fill a bath
before Christmas, if not at the rate of a heat bank,
unvented cylinder or pumped gravity system.

Please behave. It will deliver 20 litres per minute filing a an average bath
in less than 5 minutes. Most people don't care of a bath fill at 5 or 2
minutes. They really couldn't care.

It uses a small internal heat store to give enough reasonable flow to
mostly
fill your bath (depending on size) before cutting back to 11 litres a
minute, which it can maintain indefinately. 11 lpm at mains pressure is
enough for a decent power shower, but not a wide bore low pressure
drencher
type, or a panel type with body jets.

If you prefer a high flow instantaneous combi
(probably more appropriate for
a drencher shower), then there Bosch-Worcester
have Greenstar versions up to 40kW.

Giving 16 litres.min. With cold added probably about 20 litres min, but for
ever.

Giving 16 litres.min. With cold added probably about 20 litres min, but
for
ever.

Given that the flowrate is calculated at 40C, why would you be adding cold?

Christian.

"Christian McArdle" wrote in message
et...
Giving 16 litres.min. With cold added probably about 20 litres min, but
for
ever.

Given that the flowrate is calculated at 40C, why would you be adding
cold?

Do they say 40C temp rise? Well 16 litres hot only, which is a very good
shower indeed, and too much for most people.

Given that the flowrate is calculated at 40C, why would you be adding
cold?

Do they say 40C temp rise? Well 16 litres hot only, which is a very good
shower indeed, and too much for most people.

No, I mean at a 40C output temperature. It is standard nowadays to calculate
using 35C delta T, equating to a incoming temperature of 5C. Summer flow
rates will be higher.

Christian.

On Fri, 15 Oct 2004 14:10:03 +0100, "IMM" wrote:



Giving 16 litres.min. With cold added probably about 20 litres min, but for
ever.

That would be impossible in the winter with a cold mains temperature
of typically 5-8 degrees.

WB may make reasonable products but can't override the laws of
thermodynamics any more than you can.


..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Fri, 15 Oct 2004 14:10:03 +0100, "IMM" wrote:

Giving 16 litres.min. With cold added probably about 20 litres min, but
for
ever.

That would be impossible in the winter with a cold mains temperature
of typically 5-8 degrees.

WB may make reasonable products but can't override the laws of
thermodynamics any more than you can.

Do you think they telling porkies?

WB may make reasonable products but can't override the laws of
thermodynamics any more than you can.

Do you think they telling porkies?

No, you are by suggesting that you can add cold water to the hot. The flow
rates specified are at usable temperature (in winter) and can't be further
diluted with cold.

Christian.

"Christian McArdle" wrote in message .net...
You don't give a budget. Assuming you want a well regarded midrange model
rather than a cheapie, the Worcester-Bosch Greenstar Highflow 440, recently
discussed might be appropriate. It will provide a good shower and still
manage to fill a bath before Christmas, if not at the rate of a heat bank,
unvented cylinder or pumped gravity system.

Sorry, remiss of me. Yes, mid-range should be good - ultimately, I'd
rather stretch the budget for a boiler and not have to worry about it
again for a good long time...

It uses a small internal heat store to give enough reasonable flow to mostly
fill your bath (depending on size) before cutting back to 11 litres a
minute, which it can maintain indefinately. 11 lpm at mains pressure is
enough for a decent power shower, but not a wide bore low pressure drencher
type, or a panel type with body jets.

We're probably not going to be bothered by bath-fill times, so an
internal heat store may be unnecessary. Not bothered by fancy showers
(body jets, etc.) but would like a decent reasonably powerful shower.

If you prefer a high flow instantaneous combi (probably more appropriate for
a drencher shower), then there Bosch-Worcester have Greenstar versions up to
40kW.

OK, I'll check them out.

Thanks Christian (and everyone else who's contributed).

Can I assume that this is a tacit agreement that a combi is the best
bet for our arrangement?

Cheers - Adam...

"Adam" wrote in message
om...
"Christian McArdle" wrote in message
.net...
You don't give a budget. Assuming you want a well regarded midrange
model
rather than a cheapie, the Worcester-Bosch Greenstar Highflow 440,
recently
discussed might be appropriate. It will provide a good shower and still
manage to fill a bath before Christmas, if not at the rate of a heat
bank,
unvented cylinder or pumped gravity system.

Sorry, remiss of me. Yes, mid-range
should be good - ultimately, I'd
rather stretch the budget for a boiler
and not have to worry about it
again for a good long time...

I think he means mid-range as mid in flowrate performance. The W-B
Greenstar HighFlow is a Greenstar boiler with a heat bank all in one
washing machine sized case.

It uses a small internal heat store to give enough reasonable flow to
mostly
fill your bath (depending on size) before cutting back to 11 litres a
minute, which it can maintain indefinately. 11 lpm at mains pressure is
enough for a decent power shower, but not a wide bore low pressure
drencher
type, or a panel type with body jets.

We're probably not going to be bothered by bath-fill times, so an
internal heat store may be unnecessary. Not bothered by fancy showers
(body jets, etc.) but would like a decent reasonably powerful shower.

It will give one. If you want a wall mounted job the Greenstar combi's will
one. They have models of various flowrates.

If you prefer a high flow instantaneous combi (probably more appropriate
for
a drencher shower), then there Bosch-Worcester have Greenstar versions
up to
40kW.

OK, I'll check them out.

Thanks Christian (and everyone else who's contributed).

Can I assume that this is a tacit agreement that a combi is the best
bet for our arrangement?

Yep.

"Christian McArdle" wrote in message . net...
If you prefer a high flow instantaneous combi (probably more appropriate
for
a drencher shower), then there Bosch-Worcester have Greenstar versions up
to
40kW.

P.S. to compare with your electric shower, it is perfectly reasonable to
suppose that the increased potential flow rate will be proportional to the
rating in kW.

A 40kW combi will produce over 5 times the shower flow of your electric
shower. A really basic 24kW combi will produce over 3 times as much, which
will be enough to make the shower really quite pleasant, if the shower head
is chosen wisely.

Sorry, a question I forgot to ask: do you know how much? Can't find
much info on their site...

Cheers - Adam...

On Fri, 15 Oct 2004 15:30:09 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Fri, 15 Oct 2004 14:10:03 +0100, "IMM" wrote:

Giving 16 litres.min. With cold added probably about 20 litres min, but
for
ever.

That would be impossible in the winter with a cold mains temperature
of typically 5-8 degrees.

WB may make reasonable products but can't override the laws of
thermodynamics any more than you can.

Do you think they telling porkies?

Not as far as they go, but they are not being complete in their
specification and are presenting the product in a better light than
its ability to perform.

Even that Alpha thing that was your special offer last month had a
more complete spec.


..andy

To email, substitute .nospam with .gl

In message , IMM writes

"Christian McArdle" wrote in message
.net...

I've checked the SEBDUK database
and got the list of 50 most efficient
boilers - we'll probably select the most
suitable from that list. Can
anyone give any extra insight into particularly
suitable models?

You don't give a budget. Assuming you want
a well regarded midrange model
rather than a cheapie, the Worcester-Bosch
Greenstar Highflow 440, recently
discussed might be appropriate. It will provide
a good shower and still manage to fill a bath
before Christmas, if not at the rate of a heat bank,
unvented cylinder or pumped gravity system.

Please behave.

**** off

--
geoff

Sorry, a question I forgot to ask: do you know how much? Can't find
much info on their site...

Ouch. The price isn't small for the Highflow.

From www.discountedheating.co.uk, who are usually somewhere near the pace.

Greenstar Highflow - 1939 inc VAT
Greenstar 40HE - 1297 inc VAT

Christian.

We're probably not going to be bothered by bath-fill times, so an
internal heat store may be unnecessary. Not bothered by fancy showers
(body jets, etc.) but would like a decent reasonably powerful shower.

And given the price differential, an instantaneous type may suit you better.

You'll get good shower performance from a 28kW combi. 40kW will do two
reasonable showers simultaneously.

Christian.

"Christian McArdle" wrote in message
. net...
Sorry, a question I forgot to ask: do you know how much? Can't find
much info on their site...

Ouch. The price isn't small for the Highflow.

From www.discountedheating.co.uk, who are usually somewhere near the pace.

Greenstar Highflow - 1939 inc VAT

They do claim a two bathrooms, although I would say 1.5. That price is vs.
good for a condensing boiler and an all inn one mains pressure simple
installation. If you install it in an awkward location then it is the
business. The internal condensate pump and long flue lengths then come into
focus.

Greenstar 40HE - 1297 inc VAT

Christian.

On Mon, 18 Oct 2004 09:20:24 +0100, "Christian McArdle"
wrote:

Sorry, a question I forgot to ask: do you know how much? Can't find
much info on their site...

Ouch. The price isn't small for the Highflow.

From www.discountedheating.co.uk, who are usually somewhere near the pace.

Greenstar Highflow - 1939 inc VAT
Greenstar 40HE - 1297 inc VAT

Christian.


In that case I don't see the point.

This device needs a washing machine space plus another 200mm access,
so probably suited to a garage.

For that money, you could get a decent combi or system boiler and a
pressurised cylinder or basic heatbank. The cylinder would take
approximately the space of the Lowflow and then the boiler can be
located easily separately.



..andy

To email, substitute .nospam with .gl

© Copyright 2004.

All parts of this Usenet posting are Copyright by the author. It may not
be sold in any medium, including electronic, CD-ROM, or database,
packaged with any commercial product, or published in print or
electronic form without the explicit written permission of the author.
The copyright of included material belongs to the original author.

For that money, you could get a decent combi or system boiler and a
pressurised cylinder or basic heatbank.

Indeed. The combination was considerably cheaper when I installed my heat
bank and system boiler. Also, the flow rate provided is not that much
greater than the 40kW instantaneous. I fear that they may have priced this
boiler out of the market.

Christian.

On Mon, 18 Oct 2004 11:39:02 +0100, "Christian McArdle"
wrote:

For that money, you could get a decent combi or system boiler and a
pressurised cylinder or basic heatbank.

Indeed. The combination was considerably cheaper when I installed my heat
bank and system boiler. Also, the flow rate provided is not that much
greater than the 40kW instantaneous. I fear that they may have priced this
boiler out of the market.

Christian.

Either that or the classic situation of pricing high for now knowing
that people don't yet *have* to buy condensing models and then waiting
to see what the competition does in the coming months.


..andy

To email, substitute .nospam with .gl

© Copyright 2004.

All parts of this Usenet posting are Copyright by the author. It may not
be sold in any medium, including electronic, CD-ROM, or database,
packaged with any commercial product, or published in print or
electronic form without the explicit written permission of the author.
The copyright of included material belongs to the original author.

"Andy Hall" wrote in message
...
On Mon, 18 Oct 2004 09:20:24 +0100, "Christian McArdle"
wrote:

Sorry, a question I forgot to ask: do you know how much? Can't find
much info on their site...

Ouch. The price isn't small for the Highflow.

From www.discountedheating.co.uk, who are usually somewhere near the
pace.

Greenstar Highflow - 1939 inc VAT
Greenstar 40HE - 1297 inc VAT

Christian.


In that case I don't see the point.

This device needs a washing machine space plus another 200mm access,
so probably suited to a garage.

For that money, you could get a decent combi or system boiler and a
pressurised cylinder or basic heatbank. The cylinder would take
approximately the space of the Lowflow and then the boiler can be
located easily separately.

You really have got it. A combi saves space with no tanks, cylinders, etc,
No waiting for hot water, cheaper installation etc,

On Mon, 18 Oct 2004 13:26:19 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Mon, 18 Oct 2004 09:20:24 +0100, "Christian McArdle"
wrote:

Sorry, a question I forgot to ask: do you know how much? Can't find
much info on their site...

Ouch. The price isn't small for the Highflow.

From www.discountedheating.co.uk, who are usually somewhere near the
pace.

Greenstar Highflow - 1939 inc VAT
Greenstar 40HE - 1297 inc VAT

Christian.


In that case I don't see the point.

This device needs a washing machine space plus another 200mm access,
so probably suited to a garage.

For that money, you could get a decent combi or system boiler and a
pressurised cylinder or basic heatbank. The cylinder would take
approximately the space of the Lowflow and then the boiler can be
located easily separately.

You really have got it. A combi saves space with no tanks, cylinders, etc,
No waiting for hot water, cheaper installation etc,

I did say decent.......


..andy

To email, substitute .nospam with .gl

© Copyright 2004.

All parts of this Usenet posting are Copyright by the author. It may not
be sold in any medium, including electronic, CD-ROM, or database,
packaged with any commercial product, or published in print or
electronic form without the explicit written permission of the author.
The copyright of included material belongs to the original author.

"Andy Hall" wrote in message
...
On Mon, 18 Oct 2004 13:26:19 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Mon, 18 Oct 2004 09:20:24 +0100, "Christian McArdle"
wrote:

Sorry, a question I forgot to ask: do you know how much? Can't find
much info on their site...

Ouch. The price isn't small for the Highflow.

From www.discountedheating.co.uk, who are usually somewhere near the
pace.

Greenstar Highflow - 1939 inc VAT
Greenstar 40HE - 1297 inc VAT

Christian.


In that case I don't see the point.

This device needs a washing machine space plus another 200mm access,
so probably suited to a garage.

For that money, you could get a decent combi or system boiler and a
pressurised cylinder or basic heatbank. The cylinder would take
approximately the space of the Lowflow and then the boiler can be
located easily separately.

You really have got it. A combi saves space with no tanks, cylinders,
etc,
No waiting for hot water, cheaper installation etc,

I did say decent.......

And that you did. Full marks!!