problems with contral heating/ hot water controls

10 Oct 2005
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United Kingdom
I have just fitted a Sunvic select XL programmer but the system isnt working properly. I have checked (many times) and the wiring for the whole system is correct. the set up is a drayton mid way valve, a cylinder stat, a drayton digistat room stat, a baxi solo 3 boiler, and circulating pump.

the probelms is as follows:

when the programmer calls for HW only, the system works as it should - the midway valve is turned to hw only, and the cyl stat turns the boiler/ pump on appropriately.

When the programmer calls for CH only, the boiler & pump come on automatically regardless of what the room stat is registering and where the midway valve is set. this is controlable by the cyl stat - if this registers satisfied, then the boiler is on permanently, if the cyl stat = calling, then the CH system works as it should (eg the room stat controls the midway valve and boiler appropriately). When the boiler & pump are going at the wrong time, the room stat will still control the midway valve appropriately, although as room temperature rises, the stat will not turn the boiler and pump off.

so to simplify:-

CH on + CYL STAT satisfied = boiler & pump on regardless of any other settings (althoguh ROOM STAT will control midway valve when it calls)

CH on + CYL STAT calling = CH works appropriately

HW on only = works appropriately

HW and CH on = works appropriately until the CYL stat = satisfied, then see the above problem

I'm tending towards the Sunvic contoller being faulty at the moment, but if this screams anything obvious to anyone out there, please let me know. this is driving me MAD!

thanks in advance
just wanted to add that I know the Cylinder stat should have nothing to do with the CH, but for some reason it has become linked with this part of the circuit.
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DarkInferno said:
It is wired up wrong.

thanks for your constructive feeback darkinferno :rolleyes:

It is wired up exactly to this diagram

I have checked and re-checked it, and nothing is out of place. It's as if the programmer is switching the live to CH on AND HW off, when CH is called for, other wise the live connection is magically jumping the switch in the room stat.
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Expected that reply, if its right then why ask? It must be working perfectly. :rolleyes:

As electricity tends to flow through wires and not through magic, I'd be happier to belive faulty wiring then magical pixies *shrug*.

Unless the programmer has gained psychic powers over the state of the cyl stat, it isn't that either.

But as you know best mate I'll leave it to you. :)

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