On Wed, 17 May 2006 03:25:21 +0100, John Rumm wrote:

John Stumbles wrote:

Mains pressure
hot/warm water ---------
from thermal store | combi |
------------------+---| DHW |------
| --------- |
| -----
| | H |
| | TMV |-------
| | C |
| -----
| |
---------------------

To save potential complications from feeding the combi with prewarmed
water (which could in some cases be *hot*), ...
---8---

Although the temperature at the inlet to the combi may be hot, there
should be no flow, therefore no demand, until the temperature falls
below the TMV set point. Therefore the combi should only be heating warm,
never hot, water.

Of course if the combi has problems with this then your plan B will be
called for.

---------
mains cold | combi |
-----------------------| DHW |-------
--------- |
-----
| H |
| TMV |-------
| C |
-----
preheated water from store |
------------------------------------------