"Andy Hall" wrote in message
...
On Wed, 16 Feb 2005 16:57:20 -0000, "Doctor Evil"
wrote:


A heat bank/thermal store, presents you with a wonderful neutral zone.
Pumps are not expensive and are far more reliable than 2-port zone
valves. You put a check valve on each CH zone to prevent back
circulation. Each pump can have its speed set to the needs of the
zone. There will be no parasitic circulation if each zone has its own
flow and return tapping off the store.


This is only true if a conventional
boiler is used or if there is a
need to introduce heat from another
source such as solar or possibly
some form of stove.

Not so.

My point was very specific and is correct.

Not so.

It is not an appropriate technique to use if a modulating, condensing
boiler is the primary or sole heat source since the boiler will not be
allowed to ever operate in its most efficient temperature range.

Not so. Any boiler will operate efficiently on a thermal store. It must
be
able to maintain a constant flow temperature.

The point was clear and correct for a modulating condensing boiler.

Nor so.

I didn't say that it wouldn't work with a store and indeed with
respect to hot water production makes good sense.

My point was purely about putting a
store between boiler and heating
load when the boiler is a modulating
and condensing type.

A store of water between (a buffer) is the best thing as it eliminates
boiler cycling.

THe effect of the store would be to
cause cycling,

Not so, cycling eliminated

- THe boiler won't have the possibility of operating at the lowest end
of its temperature range

It will if an outside weather compensator dictates the temperature of the
bottom of the store.

- It will be cycling (albeit occasionally) which is not as efficient
as a continuous low power burn.

Not so. Boiler cycling eliminated as the thermal store (buffer) prevents
boiler cycling. Boiler directly connected to the rads cycle once the heat
demand is below the lowest boiler output.



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