Viessmann 200 60kW E3

[Marty92]

Hi,

I am having an issue with a Viessmann Vitodens 200 installed for a client.

The boiler is a B2HA 60kW commercial with Combustion controller lockout fault E3.

It is weather compensated, system Type 4 the mixer is a 1 1/4” Divicon

I have spoken to Viessmann who suggested the Divicon was needed

All controls are from the boiler, there is a LLH and both the mixer and the DHW valve & Pump are downstream of this.

Boiler set to achieve DHW temperature of 60, cylinder thermostat set to 70 (ie never off unless there is an overheat situation)

I have tried all sorts now but this fault causing lockout is driving me more nuts

Any commercial Viessmann guys out there with insight before Viessmann themselves come out?

Thanks

 

[ShaunCorbs]

Overheat or main pcb normally I would look at circulation are they moving the heat away fast enough

does it happen all the time or when they have been on for a while ?

 

[Marty92]

Hi Shaun,

It happens at gas calibration, every 4-5 fires, usually 3 hours + after demand.

I spoke to viessmann again today to try and understand the fault , I wanted to know the logic layout for the fault, not much luck!

They say the cause is lack of heat transfer but measured where? He suggested it might be boiler flow but that makes little sense.

I had thought it would be measuring rise on the DHW but the boiler doesn't know the
stored volume...

Yesterday I tried adjusting the DHW probe and adding a bit of heat paste, today no lockouts so far...

A couple of other things i’ll try if the issue persists

6F in coding level 2 is DHW limit setup think i’ll drop that to around 40%, Coil is only a baby so 25kW should keep it happy

60 in coding level 2 is boiler delta over the DHW set point temperature, currently 20 so a boiler temperature of 80, might reduce this to 10.

I have set the DHW pump to speed 1 which with virtually zero head Is still a tad fast for the coil