I am not sure where waists come into this. A number of contributors
to this NG have bought this and found it useful, even if it has been
for a one off installation. So far, you appear to be the only
dissenting voice, but why would I find that surprising?
Spending £20 in the context of a cost of materials of typically
between £1000 and £2000 is nothing and the information is from the
recognised industry association, derived from the relevant official
and informed sources.
That's a matter of opinion and expectation of performance.
The book has arrived and its not a waist of time even for a one off.
i'll have a look at the heatbanks - but IMM you need to take note that
most of us on here don't need "idiot proof" installations and as for
"cheaper than getting a professional in".
We are damn good and confident in doing a professional job ourselves (doing
doesn't mean that you don't want to understand how the system works or
how to install it properly.
This news group is supposed to be about obtaining information to allow
people to go about it themselves.
there I've said it. lol
That is so. And doing it the easiest and most effective way too. If you
think you can do a professional job then fine. I have found no DIYer that
has ever done what I would call a professional installation. Not one. And I
seen quite a number of them. The one box solution cuts out a hell of a lot
of work and design and is still cheaper than getting a pro in. Think
very hard, you may be overconfident.
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com ).
Duncan's trade, but I myself have served a 4 year Mechanica
Engineering Apprenticeship and am probably far more capable of making
decent joint for a water/gas system than many so called "Professionals
out there! When you are working on High Pressure and Cryogenic system
for years there are far more skills involved and necessary precaution
to worry about.
Like Duncan, the reason I post on this kind of forum is to get som
understanding of the things that I am not sure about, boiler choice
system design, etc and not actually doing the job.
I know by experience that if I was to employ a so called "Professional
to install a system, then it is likely that he will do a shabby job an
I will regret.
As I say this is "my experience" of employing people to do jobs aroun
the house, whether it is fencing, double glazing or I am sure plumbing
I am not for one minute suggesting that either you or anybody else fo
that matter who give extremly useful information here, fall in thi
I do agree with the "One Box" solution approach, assuming as other
have said that it meets the requirements and that is my dilema a
While a one box solution makes installing simpler for unskilled or
cackhanded people like IMM - and will appeal to some pro installers by way
of increased profits - it ties you down to the maker for the inevitable
External components such as pumps, divertor valves and of course a
storage cylinder allow you to buy the finest available - and a choice of
makes at replacement time. And probably makes such replacement easier due
to better accessibility.
All to often a maker will withdraw support on a product in an attempt to
force new sales, before that product is truly worn out. So I'd prefer to
keep this possibility to a minimum.
Installing a new system on a DIY basis is really something it is worth
taking time and trouble getting absolutely right, as it should then have a
long, long life.
Of course if you are tight for space, a one box solution may be the
answer, but it is far from the 'one size fits all' ideal solution that our
resident clown is so keen to promote for reasons best known to himself.
*Atheism is a non-prophet organization.
Dave Plowman email@example.com London SW
On Fri, 18 Jul 2003 18:41:23 +0000 (UTC), "duncan"
It will give you a good appreciation of the steps in radiator and pipe
sizing, radiator derating and so on plus the issues with pump
selection and setting, organisation of pipes to avoid pumping over
You can then get a lot of information from manufacturer's web sites.
It does mean that care needs to go into the sizing and branching off
of pipes so that there is reasonably good balance of flow naturally.
Then there are techniques with flow restrictors, blending valves etc.
if you need to go further.
This is the big advantage of a cylinder. You can make it adequately
sized to be sure that you will always have a plentiful supply,
regardless of the draw rate.
For example, I have a cylinder with multiple tappings on the top which
will take 22mm pipework. It is fed from the roof tank in 28mm pipe.
The effect is that I can run two baths at full tilt or a bath and a
shower or two showers at 25 litres/minute each.
You can go for very large combi boilers and get a flow rate of up to
about 20 litres per minute with a 35 degree temperature rise.
For a lot of the year when the mains water is warmish - say 15 degrees
and above, you will be able to mix the heated water with quite a lot
of cold - e.g. in a shower mixer.
However, if you are concerned about the worst case, that would be in
the winter when the water supply can be well below 10. If you
consider that the user temperature in a shower is around 40 degrees,
you can see that almost all of the boiler hot water will be needed and
little opportunity to add cold. Therefore you end up with 20 litres
per minute between two showers - i.e. 10 each. Then it becomes a
matter of opinion as to what you find acceptable. Personally I feel
that 15 litres/min in a power shower with adjustment between hard jets
and drench mode is about the minimum - others say less or more.
If you already have a shower in place, try measuring the flow rate
with a bucket and stop watch to get a feel of what you are getting.
The well known site on these is DPS. www.heatweb.com although the
cylinder manufacturers are making them as well.
The main advantages that you can get out of one of these are that
- the primary circuit can remain vented so that the bulk water in the
cylinder is not pressurised. Sealed cylinder pressurised systems
require a BBA or IoP approved installer to fit them
- The cylinder can store water at higher temperatures than if it is
used for hot water. It can be at 80 degrees rather than 60, so a
third more energy is stored in the same space. The mains cold water
is fed through a plate heat exchanger external to the unit and then
the primary water from the tank is pumped through the exchanger when
there is demand to heat the water. This type of exchanger is highly
effective on heat transfer and so if the water supply is up to it,
much greater flow rates than with a combi can be achieved.
As the store is being used, the boiler will be adding heat back in,
although typically at a lower rate than you are using it.
To give a simple example, you might be drawing hot water at a rate
such that 60kW is required to heat it to the extent required. If the
boiler is able to deliver 30kW into the cylinder, then the net rate of
use is 30kW. Therefore the amount of hot water that you can get at
the 60kW rate is twice as much if the boiler is adding heat in, using
this example. Once the stored energy runs out, the flow rate would
have to be halved to maintain the same temperature rise. Make sense?
The same additive effect occurs in a conventional cylinder of course -
the difference being that the amount of energy stored is 25% less.
If you are going the condensing boiler route, it won't be as efficient
with a thermal store as it can be with a conventional cylinder because
the operating temperature is higher. It's also better to run the
radiators separately from the primary circuit than from the store.
A fast recovery type. Vendors of these include Albion and Telford
among others. These have various arrangements to increase the
surface area of the coil - e.g. more turns, multiple pipes, etc. The
point is to increase the transfer rate of heat so that the water is
heated more rapidly, and if you have hot water priority arrangement
that the boiler is not taken from heating the house for too long.
There should be plenty of those. Thrills and spills for all the
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