Vaillant EcoTec810 plus Heating Not Working

[Timo1791]

Hi newbie to boiler issues here..
I have a problem with my boiler that I've been unable to solve. No indication of failure just happened. I hope you can help me fix it please.

My setup:
Family house, with Vaillant EcoTec810 Plus boiler + one Siemens RDJ10RF thermostat

Context:
Heating was working fine this morning but was set to off during most day. Turned on late afternoon, popped out for an hour and radiators were not hot. Boiler pressure was at 1.2 bar.
I've bled each radiators a small amount. Then pressurised system to 1.5 bar. Then turned heating on from thermostat which did ignite the boiler only temporarily for 5 secs. In pressing the override on the receiver it does not ignite the burner but the boiler clicks and fans start and stay on. I relearned the thermostat which is registering on/off of the boiler but no burner. Pressing the flame button does the same thing also.

The problem:
The hot water system works perfectly, but the heating system is not working at all. The boiler is not igniting but does so fine for hot water. The boiler clicks and fan stays on.

Signals:
The boiler shows status code 5.0 not sure what this means.
If I press the button on the thermostat receiver, the heating SEEMS to try to start, it turns on the icon of the heating pump (although not the burner), and remains in 5.0. There is an arrow symbol. It never starts the burner, and heating doesn't work. No error code is shown at any time.
I'm attaching some pictures for reference.


Can you please help me understand what is happening?
Thanks a lot in advance!!

 

[CountryFan]

It looks and sounds like a circulation issue, possibly the diverter motor has failed. Needs a gas safe registered engineer to look at it really

 

[Timo1791]

Do you know much am I looking at for a fix ?

 

[CountryFan]

Do you know much am I looking at for a fix ?

Not really as self employed and businesses up and down the country charge different rates. New diverter valve will be in the region of £100 - £150, motor isn't sold by Vaillant as a spare and would need to be obtained from elsewhere like eBay and is in the region of £20. Then there's labour on top - new motor about 5 minutes. New diverter valve about 30 minutes.

 

[Timo1791]

The engineer is booked in tomorrow. I'll update tommorow for anyone that's interested.

 

[Timo1791]

If it's a diverter valve or any other part for that matter would you always go with the genuine Vaillant one (brass) ? This one has lasted as far as I'm aware could be the original.

 

[Timo1791]

Engineer replaced diverter valve, I managed to get genuine part. But instead of no heating, now I have heating but no hot water.

Problem:
However, following replacement now there is no hot water but heating is working. Engineer advised all tests have been done and could confirm hot steaming water was present.

Signals: see pic attached
No error codes.
When hot tap is on temp rising from 60deg to 87.
Tap symbol is on
Flame symbol on
Egg timer symbol
Also now the radiator symbol now flashes sometimes. Don't recall this happening.

What I've checked:
The left side tap is now super hot to touch, you can barely touch it with heating and hot water on.
Turning hot tap calls for hot water

Should i ensure diverter motor is now checked ?
Any other suggestions would be greatly appreciated.

 

[Timo1791]

Engineer replaced diverter valve, valve was the original one). I managed to get genuine replacement part. But instead of no heating, now I have heating but no hot water.

Problem:
However, following replacement now there is no hot water but heating is working. Engineer advised all tests have been done and could confirm hot steaming water was present.

Signals: see pic attached
No error codes.
When hot tap is on temp rising from 60deg to 87.
Tap symbol is on
Flame symbol on
Egg timer symbol
Also now the radiator symbol now flashes sometimes. Don't recall this happen

What I've checked:
The left side tap is now super hot to touch, you can barely touch it with heating and hot water on.
Turning hot tap calls for hot water

Should i ensure diverter motor is now checked ?
Any other suggestions would be greatly appreciated.

 

[Agile]

You would need to see if the diverter valve is moving when the hot water tap is turned on.

 

[CountryFan]

Was the whole diverter changed? Possibly a trapped wire on the diverter harness. Press the I button when running hot water, what does it display? S.14 is running hot water. If you do it from cold, then feel the flow pipe, if this begins to heat up then it’s going down the heating circuit.

 

[Timo1791]

Was the whole diverter changed? Possibly a trapped wire on the diverter harness. Press the I button when running hot water, what does it display? S.14 is running hot water. If you do it from cold, then feel the flow pipe, if this begins to heat up then it’s going down the heating circuit.

Yep happening exactly as described. S.14 and the left pipe is getting hot. Also noticed radiators are hot even though heating has been off since afternoon.
When tap is turned off getting S.17
When boiler stops completely getting S.30

 

[CountryFan]

Ok, s.17 is pump overrun for the hot water circuit, S30 is no heating demand/blocked by room thermostat. If the left pipe is getting hot, and the radiators are heating up then it’s circulating into the heating circuit, as I said, could be a trapped wire not causing the motor to move over or coincidentally crap in the system is stopping the motor moving.

If you’re able to, remove the cover and take a photo of the diverter valve/motor and wiring tie the black or brass coloured one that connects to the pump.

 

[Timo1791]

Not sure if I've taken correct pics. Let me know if you want anymore.

 

[Timo1791]

Ok, s.17 is pump overrun for the hot water circuit, S30 is no heating demand/blocked by room thermostat. If the left pipe is getting hot, and the radiators are heating up then it’s circulating into the heating circuit, as I said, could be a trapped wire not causing the motor to move over or coincidentally crap in the system is stopping the motor moving.

If you’re able to, remove the cover and take a photo of the diverter valve/motor and wiring tie the black or brass coloured one that connects to the pump.

Does that look right to you where the valve is digging into the bottom housing ?

 

[CountryFan]

Does that look right to you where the valve is digging into the bottom housing ?

Not sure what you mean, but it looks ok to me. The red plug in connector looks a bit suspect though. If you unplug the part where it connects onto the motor, check the pins are all straight.