no HW only. boiler icons swapped

[Nikd1]

Hello,

I recently moved into a new house with ecotec 415 gravity fed system. not sure if working initially but I have since installed a nest thermostat. I have been over the wiring several times and all seems to be fine. I hear the thermostat click when HW and CH demands are triggered. I hear the 3 port valve spin when CH triggers.

my problems are as follows:
with no demands from thermostat, boiler shows tap but not firing.
with CH only, as above.
with HW only, tap and radiator show, boiler fires to HW.
with CH & HW, boiler fires to CH, tap and radiator showing.


I think some settings on the boiler may be incorrect, anyone have any suggestions?

 

[EvilDrPorkChop]

Sounds like your wiring is incorrect. On the Heat Only boilers from Vaillant unless you are using Vaillants own wiring centre the tap on the display means nothing. In fact if you go to the HW setting on the boiler and minus it to 'Off' the tap will go away. The Radiator symbol is the only one you need to know about as this is when there is a demand on the system, whether that be HW or CH from your Nest.

It sounds like you've not wired something correct at your motorised valve, so that when CH is being demanded on it's own you aren't getting a S/L from the micro switch.

You should also note that with the Vaillants you aren't allowed to remove the front cover to complete wiring tasks as this breaks the room seal which needs to be checked and other checks by a GSR engineer after being refitted. However you don't need to remove (And I assume you haven't) the cover to complete what you are trying to do.

 

[Nikd1]

Thanks EvilDrPorkChop, thats really useful to know about the symbols on the boiler screen! I had been wondering if it might be something in the valve, I will see if I can diagnose

 

[Nikd1]

I disassembled the 3 port valve and identified that only 1 microswitch was being triggered when the valve moved. I bent the contact of the second so that they both click on the movement. reassembled now and tested. IT WORKS!!!! thank you

my only slight worry was that when CH was activated, the valve moved to position then seemed to bounce several times against the microswitches clicking them on and off about 10 times before it set into position. is this normal?

 

[Nikd1]

ahhhhh! think I did something wrong. after the clicking the boiler turned off. when I turned off the valve moved back but at the end of travel there is a big thud :S. im guessing I didnt have the gear alligned properly when I reassembled?

 

[Nikd1]

dont know what the thud is about. hope its not damaging anything.
The valve bounces on the microswitches until until it catches 1 on without the other then stops at which point the heating turns off. wondering if maybe I should put it back the way it was..

 

[Nikd1]

perhaps the thud is because the valve is moving while the circulation pump is on?

 

[EvilDrPorkChop]

There won't be any thud down to a circulation pump. It sounds to me like you've probably knackered the head in messing around with it, put it back the way it was and double check your wiring.

 

[Nikd1]

its back the way it was and put microswitches back so only 1st comes on when lever reachest bottom and 2nd switch does not trigger.

wiring from photos is as follows, note that the circular box lines between the 3pv and the main wiring block so colours change.
red from 3pv -> HW cylinder blue.
White from 3pv goes to CH on at nest (3).
grey from 3pv goes to HW cylinder yellow/green.
seperatly a line runs between nest HW on (6) and HW cylinder brown.
within the next, Live is connected to (2) and (5)

boiler signal runs to valve live and HW cylinder blue

any help in identifying the fault would be much appreciated.

 

[Nikd1]

FIXED! added line between 3pv grey+HW cylinder green/yellow to nest (4) for hot water off. had previously read that was not required but obviously it is (especially knowing what I have learned over the course of the day!)

really appreciate your help not sure I would have had the confidence to get there without the nudges.

 

[Ziggie]

Just about to suggest that- itis needed for heating only setting