Vaillant Ecotec plus 630 no heating hot water

[terryplumb]

Ok ,cheers. I wonder if on meddling with the zone valves may have introduced your new problem.

 

[ianmcd]

@terryplumb - the boiler is going on short-cycle when there is no CH and HW demand. Ian's asked for a photo of the boiler display when it comes back on and short cycles. This is what i was referring to in my previous message.

the way that your zone valves work, the small motor , when a demand is made opens the valve, once the valve is fully open it makes a small micro switch, this switch tells the boiler to fire up, sounds like one of the switches is stuck in the demand position (very common) the valve closes but the boiler doesnt know that the valve has closed hence why it keeps coming on, but the heat cant get out so just runs through the by-pass, it is an easy enough fix once you identify which valve actuator head is causing it

 

[RMS786]

@terryplumb - yes it is very likely i have introduced this while putting the actuator head back on the valve.
@ianmcd - i have a feeling that this may be the HW motorised valve causing this. how do i go about fixing this? Do i have to replace the motorised head?

 

[ianmcd]

@terryplumb - yes it is very likely i have introduced this while putting the actuator head back on the valve.
@ianmcd - i have a feeling that this may be the HW motorised valve causing this. how do i go about fixing this? Do i have to replace the motorised head?

yes you are best to replace the head , do you have a multi-meter and are you comfortable with electrics ?

 

[terryplumb]

Replace the actuator . To establish it is the hot water one ,disconnect the switched live from it at the wiring centre ( put it into an insulated terminal block). If that resolves the issue you know it's that valve. If it doesn't, re instate the wire. And repeat with the Ch zone valves switched live.
Obviously isolate the electrics first !

 

[RMS786]

@ianmcd and @terryplumb:- i have gone all out and completely disconnected the valve head from the electric circuit. Yet i still see the same behaviour as previously described. Is it safe to rule-out atleast the valve-heads to not be the cause? Not sure what to check next?
Flow temperature is set to 65 degs. I would think that the boiler would only fire up when there is a CH or HW demand. Unless, not a suitable approach, but it comes on to keep the water within the boiler pipework/heat exchanger at the specified flow temperature.

Any thoughts on what could be causing this short-cycling infinitely?

 

[terryplumb]

You have completely removed BOTH valves wiring at the wiring centre ??

 

[ianmcd]

i have gone all out and completely disconnected the valve head from the electric circuit.

How did you remove the wires ? I know that you have posted a pic of both actuators removed from the valves, that wont make any difference whatsoever

 

[RMS786]

I have removed the wiring from the wiring centre except the ground connection from both valves. Attaching images.

Grateful for your contunued assistance.

 

[terryplumb]

I hope you made a careful note of which terminals each wire was connected to !!!
There can't be a switched live to the boiler from that wiring centre with the actuators removed ,is there a frost stat wired directly to the boiler ?

 

[ianmcd]

NEVER rely on colours in heating wiring, what you are calling "ground" will be earth here , but the colour means absolutly nothing, looking at your pics some green/yellow wires are being used as lives

 

[terryplumb]

NEVER rely on colours in heating wiring, what you are calling "ground" will be earth here , but the colour means absolutly nothing, looking at your pics some green/yellow wires are being used as lives

Which are Ian ? They all appear to be connected together in the same earth terminal block .

 

[RMS786]

@ianmcd @terryplumb - i have now removed the only remaining connection from the two valves. I have attached the wiring image as it was befire i touched it and now. There is no change in behaviour.

The only other thermostat apart from Hive is the one in the hot water tank as far as i am aware.

Can't see what can be calling the boiler for heat or why does the boiler appliance think it needs to get the pump going and fire itself up?

 

[terryplumb]

The only switched live to the boiler from that wiring centre is the grey wire that is in the same terminal block as the two orange wires from the zone valves. With both orange wires disconnected there is nothing to energise it. The boiler does have a seperate permanent live ,but I can't envisage a way that could fire the boiler up ,unless there is an issue inside the boiler on the electronics side ( which is not my forte ,maybe Ian can shed some light on it)
One thing's for sure ,the issue is not the zone valves ,or the wiring centre. But an external component ,like a frost stat ,or the boiler directly.
The boiler controls the pump ,so when it fires up it energises the pump, and keeps it running after the boiler ceases combustion ,in order to dissipate inherent heat.

 

[RMS786]

Thanks Terry. At least it rules out valves related issue. The whole setup boiler, plumbing/pipes, rads everything put in place 8 months ago and ha e had no trouble with it. I am hoping it is nothing to do with the components and more to do with configuration/setting. Hopefully the wiring as it was done before is ok and not the cause if this issue. I cannot say for sure that this problem did not exist before but inclined to believe that it did not exist before.

Hopefully Ian can shed more light.