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Andrew Gabriel
 
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In article ,
"Doctor Evil" writes:

"Andrew Gabriel" wrote in message
...
In article ,
John Stumbles writes:
pauliepie wrote:
Is it possible to have the heating circuit off a combi split into 2
zones, one for a ground floor the other for upstairs.
If so, what controls are required, etc,etc?

2 * 2-port valves etc, but you'll also need a bypass (e.g. pressure
relief bypass) so when the last valve turns off and tells the boiler to
stop theres somewhere for water to go while the boiler keeps the pump
running as it cools down


I did it using a mid-position valve, so there is no mode in which
there's no flow path, without needing a bypass. I did however
design a circuit to drive the mid-position valve and boiler demand,
using two stats as input controls.


Good idea if the boioer has an auto heat disipation function. But two 2-port


Also, for pump run-on, and boiler auto-start for frost protection,
and daily pump exercising.

valve are a lot simpler and more reliable than one mid-position 3-way valve.

If you have TVRs on all rads and close the pump will be pumping nothing. So,
it is wise to have the rads where the stat or programmers stats are with no
TRVs fitted.


Indeed, the radiators in the rooms with the stats have lock shield
valves at both ends, i.e. no TRV and no hand operated valves.

--
Andrew Gabriel