On Thu, 17 Jul 2003 21:13:08 +0100, "IMM" wrote:

"Andy Hall" wrote in message
.. .
Any recommendations for sources of information on
designing a central heating/ho****er system for please.

have found sites that provide info on rating the boiler/rads
but nothing on the actual design. type of heat storage etc.

duncan

What do you intend to do? As you are a
DIYer go the combi route.

Why? That's a bit of a put down isn't it.

How is recommending the best rote for a DIYer a put down. This is uk.d-i-y.

Because you are suggesting that a single box combi solution is the
most appropriate for a DIYer on the basis that it is apparently
simple.

The reality, of course is that there are a whole load of issues such
as incoming water mains pressure and flow, appropriate sizing of
pipework, flow restrictors and a whole raft of other issues to deal
with to make it work properly.

You don't know what the usage requirements are so how can you be so
sure that this is the right solution. Why not a thermal store, or
have you gone off those this week?


Buy a high flowrate combi. Not all combi's
give a trickle for hot water. They
are easy to install with minium design in
CH pipework and rad sizing.

You connect up 5 pipes, run a power supply
and a wire for a thermostat or thermostat/clock
from the combi. Superb for high pressure showers.
A doddle.

The radiator sizes and pipework still need
to be calculated properly Use of a combi
doesn't make a fundamental difference to this part of
the design.

Don't go for complicated cylinders, tanks, motorised valves, control
systems, etc when there is no need to.

Come on. It's not that difficult.

A one box solution that professional experts have incorporated all the
design and components is by far the best option.

You know full well that there is more to it than that.


We don't know whether Duncan has a
requirement that doesn't match a
combi.

That's why I said get back to me.

The rad sizing can be done by using
one of the many on-line rad calulators.

These are useful, but are not bug free.
I have seen mistakes in the
U value numbers in one program and
another doesn't calculate heat
gains properly.

They give a good ballpark figure.


I have seen U values in at least one that are out by a factor of 3:1
on a material that mattered. This led to a 2:1 discrepancy with
calculating by hand using the Building Regs numbers. The latter was
correct.

That is not to say that the programs arenot useful, but just using
them blindly without understanding the maths that they are doing is a
recipe for problems.

On an investment of this size in money and time, it makes more sense
to sit down for a couple of hours with a piece of paper and a
calculator and to check properly.






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..andy

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