On Fri, 22 Jul 2005 00:20:26 +0100, "Doctor Drivel"
wrote:
No by-pass, which could go wrong and wreck your boioer, with thermal store.
Now you really are scratching around.
Do you have a dud batch that you are trying to return to the
manufacturer or something?
Few components. It is simple and highly effective, reliable and efficient.
and a bunch of compromises
No compromises whatsoever. All aspects: CH, DHW and Boiler are optimised.
Not with your arrangement.
that make no sense when a modulating condensing
boiler is used.
No need for such complexity when thermal store is used. Modulating boilers
in themselves are compromises.
Everything's a compromise. Defeating control systems unnecessarily is
pointless.
A pump is a pump whether it is
fitted inside a boiler or outside.
Some modulates to system pressure - Alpha.
Sigh......
The extra thermostats, relays, switches,
pumps and other paraphernalia are
superfluous if the system is designed
as the boiler manufacturers
intended and not as a Heath Robinson
project like you are suggesting.
This is utterly pathetic, bending your system to suit the whims of a boiler
manufacturer.
Who knows how to correctly match his heat source and control system to
a standard load.
A designer has control of a system using a thermal store.
You are attempting to gild a lily and painting it with ****e instead.
The store a neutral point at the centre of the system. The boiler is heat
source, that is all.
That depends on the boiler. If it's one of the budget range that you
sell because you get free trips to Eyebyeza then quite possibly.
If it's a decent quality one with integral controlled pump, conrolled
modulating burner and weather compensation then it is a great deal
more.
I am surprised that you even tried that one. Actually, no I'm not.
The one aspect of the system can be optimised fro the
rads which also optimises the boiler performance - by using a weather
compensator.
Waffle.
It is designed to be standalone
and for certain applications is
useful.
In this is it brilliant and ideal and no need for a boiler to be involved.
However, having flow rate controlled
by the same controller as the boiler
firing rate and temperatures will
by definition be a superior solution
simply because the control systems are closed loop
and not disassociated as you are suggesting.
Not a superior solution. The weather compensator decides the rads flow
temperature and then ensures a store of water is at that temperature. A
simple boiler is used to heat the stored water to the desired temperature,
maintain the boiler at optimum operating condition for efficiency, which
also eliminates boiler cycling. The mass of water ensures this. The boilers
is on full flow all the time as no rads with thermo valves to close down the
flow. Always at the right optimised temp for the system.
Complete waffle. What desired temperature? You still haven't
explained how you propose to optimise for the maximum efficiency of
the boiler (low temperatures), the requirement for the store to be at
high temperature for DHW production and the needs of space heating
(variable to match the weather conditions.
You can't achieve all of these objectives with a single store. Two
would be required and then the boiler would still be run non optimally
for space heating.
Optimisation of temperature is best done
via a weather compensator, not the
boiler.
Optimisation of temperature is best
done with an outside temperature
sensor connected directly to the
boiler electronics and taken into
account by them when directly
controlling the pump and burn rate.
This also optimises efficiency.
Not so. Best is have a mass of water at the correct temperature for the
rads dictated by the outside weather compensator. This eliminates:
- boiler cycling totally.
No it doesn't.
- boiler interlocks
No it doesn't
- by-passes
Irrelevant.
- room stats that control a system or heating zone
Big deal.
Promotes:
- efficient optimum boiler operation, always operating at the lowest
temperature set by the weather compensator
No it doesn't unless two stores are used and even then the boiler does
not have the opportunity to modulate down to most optimum rate during
space heating because the control is defeated.
- independent room temperature control, not overriden by overall system
temperature control
Achievable whatever.
- quiet CH zone operation
Achievable whatever
- instant heat at rads
Second order effect on rate of rise in room temperature
- Instant DHW
Achievable in many other ways as well and a store is a good way for
this part, just not for space heating with this type of boiler.
- few overall part
highly debatable
- no complex parts, apart from weather compensator, which is not complex by
todays stadards.
No complex parts either way.
- simple parts: simple boiler, simple thermo rad valves simple pumps
the discussion is about a modulating boiler not a conventional non
condensing one.
Unless you split the store into
discrete and separate sections or have
two stores, you can't achieve any
accuracy of control, especially as
you only have one source of heat
into the store.
The store can be split into two temperature zone with the same cylidner,
both temp zones heated via the same heat souces.
There is very little splitting possible
because the water will naturally convect
and form a single temperature gradient.
Nonsense. Distinct tem,temperature zone scan be maintained.
Even you (actually especially you) can't defy physics.
You cannot control a temperature gradient in a single body of water in
two separate and discrete entities which is what you are suggesting
here. It will naturally convect to form a single one.
If you wanted to tap off at a certain point on a cylinder to get a
lower temperature or deliver a lower temperature in a fixed way, that
is reasonable.
However, you have been suggesting that the needs of DHW production
(80 degree storage) and spae heating with weather compensated
temperature control of the stored water is possible in a single
vessel. It very obviously isn't
--
..andy
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