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Harry Bloomfield[_3_] Harry Bloomfield[_3_] is offline
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Default how hot do you run you CH boiler

on 12/01/2019, John Rumm supposed :
So you would need a bit of rejigging to move to split temperature operation.
The VR weather comp replaces the timer and stat. You probably want a pair of
two port valves in place of the mid position valve - although with a bit of
thought you may be able to achieve the logic required with what you have.
Swap the cylinder stat for a NTC thermistor, and add a suitable wiring
centre. You would need an extra cable from the cylinder to the boiler (that
threw me, I was expecting the cylinder NTC to connect to the wiring centre!),
and to install an external NTC somewhere.

Doable enough, but whether its worth the hassle at this stage only you can
decide. It might knock a few percent off the gas bill, and will make the
place a bit more comfortable year round.


It sounds like a lot of work, just to get around a limitation of the
boiler design. I have though, my eye on a 470 complete with the outdoor
sensor.

So to check my understanding - The 470 is a complete time-clock and
system monitor and room temperature sensor built into it? With the
outdoor sensor, it becomes clever system able to adapt to set the
boiler temperature as needed. It has the built in function to monitor
an NTC on the HW cylinder and that temperature can be set separately.