"Ed Sirett" wrote in message
news
On Wed, 12 Jul 2006 20:41:01 +0100, Doctor Drivel wrote:


"Ed Sirett" wrote in message
news
On Tue, 11 Jul 2006 18:37:29 +0100, Doctor Drivel wrote:


"Ed Sirett" wrote in message
news On Mon, 10 Jul 2006 21:20:13 +0100, Willi wrote:



I will be looking for wall hung, condensing, good efficiency. Not
Combi,
for a 4 bedroom house. vented fully pumped system.

.....are you a member of the flat earth society as well?

Dr Drivel
Can i ask what makes you say that? Are you saying you would rather
have
a
Combi?
I will consider all options. (but not warm air, however good they are
now).
What are the advantages of a Combi? I guess space as a hot water tank
is
not
required, but what are the others?
Regards, Will

It's probably time you had a look at the boiler choice FAQ and the
heating
section of the main FAQ.

I would say give it a miss as it's 20 years out of date. Get it
updated.

You have made this comment several times of late.
I would be happy to update the FAQ if you could be more specific.

Here is the post. The FAQ parts in quotes.

Have a read of the BoilerChoice FAQ it may help.

Or may not:

"Vented HW cylinder.
This is still the norm for most houses. With a modern cylinder and
correct
controls there should be no problem with running a bath every 15-20
minutes.
Cylinders are now required to have a good level of insulation (not the
old
jacket insulation). New replacement cylinders will be able to heat the
whole
cylinder from cold in around 20-25minute,"

20 to 25 minutes? Only a quick recovery cylinder can do this. The
normal
Part L is rated at 30 minutes warm up if all criteria is met in boiler
temperatures, flow, etc. A quick recovery with a condensing boiler can
reheat in 10 to 15 minutes depending on boiler size. They also enhance
condesning efficiency. There is no mention of quick recovery cylinders in
this FAQ.

The relevant standard mentions times around 20 minutes - for Part L
compliant cylinders. Suggestion not upheld.

NO. Maximum 30 minutes, most go slightly better to keep with Part L.
Gledhill say:
"British standard
A cylinder/tank to this standard will have an approximate re-heat time of 25
minutes with a suitable boiler and a pumped primary circuit."

Quick recovery cylinders are a reality and popular and "enhance condensing
efficiency" at the same time "downsizing an existing cylinder". In most
cases the owner never runs out of hot water as the boiler is replenishing as
fast as it can be drawn off.

These need mentioning as they are there and relevant. The two relevant
points are in quotes.

"Unvented HW cylinder:
Offers HW at mains pressure together with excellent flow. These are
expensive and can only be installed by qualified people. To justify the
expense you really need to have an excellent water main at least 25mm
diameter plastic pipe. Results will be adequate but probably not worth
the
cost if used with an ordinary lead or 20mm plastic incomers. "

The all important annual service is omitted. It will cost £60-100 a year
to
have serviced. That is over £2,000 over 20 years. They also have the
potential to explode:

The potential to explode is eliminated by
having the only possible method
of heating which could cause a problem
(electricity) to have two thermostats
(one of which locks out) also there are
two pressure relief valves, and one temperature
relief valves.

The potential to explode is NOT "eliminated" It CAN explode. The potential
is "reduced" by safety features. People need to be aware of the dangers and
that unexploding versions are avialable giving identical performance, such
as vented thermal stores and heat banks.

There is no manadatory requirement to have
the unit serviced

"Every" makers have them annually serviced. If not the insurance will not
pay up in a claim. Gledhill say:
"Unlike unvented cylinders BoilerMate A-Class does not require an annual
service"

The regs recommend a service and the makers insist on one.

Also look at this:
http://www.heatweb.com/products/cyli...k/pandora.html

People must be made aware of the extra annual cost to maintain this
potential bomb. "There is an extra cost".

It is possible to create a hazard by
incorrect installation as indeed it
is with a vented cylinder (I've seen
one this year with a valve on the
outlet vent pipe).

NO change.

The FAQ is not about incorrect installations at all. Focus on what it isn
about. You are irresponsible and need to learn more about unvented
cylinders. Your word "eliminated" is indicative.

"Thermal sto
Offers most of the advantages of the Unvented cylinders, costs are
similar
but may be diy installed. The flowrate is still pretty good (around 20
litres/min). Can be used to integrate other sources of heat (solid fuel,
solar) or facilitate underfloor heating."

No mention of the heat bank variant of the thermal store (Heat banks use
plate heat exchangers, stores use coils), which can give flowrates of 40
litres/min or more.

Too much detail. Splitting semantic and linguistic hairs is not my style.
I might add "at least 20 litres/minute or more".

That is irresponsible as the average heat bank can deliver 40 litres/min.
TWICE what you say. A minimum of 20 litres is misleading. Thermal stores
and heat banks are different, even if you think they are not. The DHW take
offs is very different indeed. The only thing they have in common on the
DHW front is stored hot water to transfer heat.

"Normal combi boiler:
Heats water only when it is needed. Instant availability (after the HW
has
drawn through and the boiler settled down - about 10-40 seconds).
Never runs out. Simplified installation. Rather limited flow rate. "

Know as an "infinitely continuous" combi, not a normal combi. Some
models
have very high flowrates that fill baths very fast indeed, and can do 2
bathrooms (MAN made in Germany), although these are not available in the
local plumbers shop being special order.

"Small storage combi:
As above but holds a store of HW to
give a prompter response and improved
flow rates for a while until the stored HW
has run out. "

The above are to eliminate the combi lag
at the taps, giving faster hot
water. This was not explained.

I think the explanation says 'prompter
response' - how is that a failure
to explain.

Too vague. Combi lag at the taps is more in keeping with what people
understand. Know your audience and those reading will be novices.

Much of the lag is the pipework and such a boiler will not
make any difference to that aspect.

You don't even mention that either.

"Large storage combi:
Washing machine sized floor standing combi
boiler. Contains pretty much all
of the benefits of a HW cylinder whilst still having a simplified
installation. Saves the space that a HW cylinder would take.
There are multiple decisions to be made based on trades-off between size,
cost, flow rate, warm up times etc."

Some are larger than washing machines
sizes. Some can supply three baths
(Gledhill Gulfstream), ACV Heatmaster.
All have no cold water tanks.

Covered by the term 'simplified installation'.

Not covered at all. 'simplified installation' is too vague. You say
washing machined sized, only two are, with most being larger, and many can
deliver 3 baths and over, whch is very different to a single bathroom job.
People need to know the range of flows which these combis can deliver. Yes
one can do 3 baths, which is highly significant - you have no mention of
such power, just open vague comments. It is a FAQ!!!!! Highlighting the
types and sizes and what they can deliver is not that difficult.

No mention of high flowrate wall mounted
combis like the Alpha CD50, which
is a mix of the infinitely continuous
combi and a stored water combi. It is
a two stage flowrate (high and low) and
never runs out of hot water.

Covered by the comment about a
'spectrum of models'.

Now that says a lot!!! Are you serious, or taking the ****? An FAQ is to
explain.

The point is that some wall mounted models can give cylinder performance.
Floor mounted models may give higher performance. The stored water models
don't always run out of hot water with a few having two stage flowrates, so
NEVER running out of hot water - all applicable to when choosing a model.
No mention of it all, just some cover all vague term.

I might add ...typically a large floor
mounted unit although some are
wall mounted ...

Best add what I suggested.

No mention of high flowrate multi-point water heaters like the Rinnai and
Andrews (relatively new innovations in the UK), which can also be fitted
outside saving much space inside a house, and do two bathrooms. A small
CH
boiler and an outside high flowrate Rinnai will be about the same price
as a
boiler and an unvented cylinder, probably less, and takes up no space in
the
house and never runs out of hot water. And if the boiler is down the DHW
still runs. Also no troublesome CH zone valves on the CH system making a
simpler and more reliable installation. Rinnais have interior models
too.
Rinnais are ideal for multi-jet showers (a newish innovation). An
unvented
cylinder would have to be "very" large,
and expensive, to compete with the
output of a Rinnai.

This FAQ is misleading and omitting information of modern equipment and
ways
gives a distorted ill-informed view. I would not recommend people take
this
FAQ seriously as it is only applicable to 1986.

The FAQ is written to help a
variety of people including those who might
not even know about a combi or a
condensing boiler (or might
even believe those terms were opposites).

Yep.

The FAQ does not contain the very
precise and detailed descriptions of
the slightly different shades of combi
boiler (some of which are much more
functional than many people may
have experienced).

It is so lacking and out of date it is misleading

If in a thread it turns out the the
discussion can usefully delve into
these matters that's fine. The purpose
of the FAQ is save time and effort
by answering the _bulk_ of the
questions

The questions which you think is relevant, but your mind is in 1986.

You have totally dismissed the Rinnais. For Gods sake!!! They are superb
for full body jet showers, which are catching on like widfire, replacing
expensive large cylinders...and can be fitted "outside" too. Two recent
innovations to the UK that can add value, and not mentioned and you don't
think it relevant either. My God!

so that the effort can be
focused on specifics in a thread.

You are welcome to write

You asked me for input. I am giving it. Now develop an attitude resenting
the significant and relevant suggestions.

If you do not incorporate my relevant suggestions. PLEASE DROP THE FAQ. It
is misleading. It comes across a very amateurish.

If it is not changed I will continue to tell people to ignore it, as it is
vague and lacks information of modern innovations. No one can make a
reasoned choice from it only the choice you think is applicable, which
revolves around 1986..