Viessmann Vitodens 100-W boiler keeps switching off

[lmhud]

I have a Viessmann Vitodens 100-W boiler which was installed in March 2010 by a registered installer.

It has been fine up to now but since yesterday it has started to switch itself off every half an hour. The control panel shows the house shape but the heating mode and DHW heating icons go off.

There is no fault icon and the burner in operation and current burner output icons also go off. The radiators cool down completely.

The only way to get the boiler back on is to reset it. Once reset, the temperature starts to come back up and all of the icons reappear and the radiators become hot in a few minutes. After about 30 minutes, the system appears to switch off again. The room temperatures are cold, it's definitely not reaching the desired temperature before this happens.

Its freezing here at the moment so could really do with some advice, we have tried to phone the installer but it just goes to answer machine, with it being Christmas it could be they are away?

Many thanks

 

[Agile]

Probably your condensate pipe is frozen ( although I would have expected an F4 ??? )

Can you disconnect the crinkly grey plastic pipe coming out on the left from the white one its probably connected to and see if its full of water?

At this time of night you could probably put it into a bucket unless you want to go outside and pour boiling water all over the drain where it is likely to be frozen. You have to pour it very slowly!

I have this vision of your installer leaving his phone firmly OFF until he decides to go back to work. In contrast mine is kept on 24 hrs a day so that I can advise anyone what to do and consider if I should go out to them!

Tony

 

[lmhud]

Probably your condensate pipe is frozen ( although I would have expected an F4 ??? )

Can you disconnect the crinkly grey plastic pipe coming out on the left from the white one its probably connected to and see if its full of water?

At this time of night you could probably put it into a bucket unless you want to go outside and pour boiling water all over the drain where it is likely to be frozen. You have to pour it very slowly!

I have this vision of your installer leaving his phone firmly OFF until he decides to go back to work. In contrast mine is kept on 24 hrs a day so that I can advise anyone what to do and consider if I should go out to them!

Tony

Thanks for the reply, do I need to switch the boiler off first?

Not sure if I mentioned this but the boiler is in the garage

Cheers

 

[mysteryman]

Tony, as ever, is correct - as far as he goes.

You will get an F4 fault if the problem is a blocked condensate drain, [but F4 can be any other failure to light].

Please check that your external controls are calling for heat, the evidence being a radiator symbol in the house in the display. If the radiator or tap symbols are absent, the boiler is not being asked to produce heat, and you need to find out why not.

 

[lmhud]

Thanks guys

First off I have disconnected the Compersate pipe at the bottom and run it into a bucket in case the pipe it connects to that runs to the waste was frozen, it has not mada any difference im afraid.

if you get an "F" Fault does it flash in the window or do you have to press anything to see the fault?
We have not had any F faults display at all.

Also when we turn it to reset, the boiler bursts into life and works very well but after approx 30 mins it shuts down. The first we notice is a drop in room temperature, when we check the boiler there is nothing at all displayed in the house icon, in fact the only thing showing is the current temperature.
There is no F code, Heating Mode, DHW display, Current burner output, Burner in operation.

Many Thanks

 

[mysteryman]

That confirms my suspicions that the boiler is not faulty. It sounds as if you are putting it into 'SERV' mode, when the burner will run flat out for emissions testing purposes for 20 minutes.

Please check that your timeswitches and thermostats are calling for heat. You need to see the tap or radiator symbols in the house in the display.

 

[lmhud]

Hi

The only time we see the Radiator or Tap symbol is when we turn it to reset and the boiler starts up again, when I turn the thermostadt up I can hear the click but the boiler does not operate, also the programeer is on and when I press the + 1hour on either the water or the Rads the light comes on but again the boiler does not fire up.

It has just shut down again this minute the only readings on the display window it the temperature 49.9 the rest of the display is clear. (just the house shape)
the Programmer (Sunvic) is on run so it should be running all the time, I have just turned the thermostadt (Sunvic) to high, heard the click but again the boiler has not come on

Is it possible the thermostadt is faulty?

How can the boiler be put into SERV mode? When the boiler is running it does have SERV in the bottom right hand corner of the display window but we have never noticed if it has always been there.

 

[lmhud]

Can anyone help please.

 

[Gasman77]

Turn it off and on again to clear the serv mode , it could have air in the flow switch will not show as a fault - the boiler will just sit there not doing much, but you need to have the rad symbol on the control panel to ensure your external controls are calling. without that symbol there you have an control ( roomstat / programmer) fault

As long as you have that, i'd try opening your TRV and lockshields fully open as it could be a lack of flow through the switch.

Further than this you will probably need a RGI to have a look inside the boiler matey.

 

[mysteryman]

There is no primary flow switch on these boilers. You have a problem with your external controls.

 

[lmhud]

Turn it off and on again to clear the serv mode , it could have air in the flow switch will not show as a fault - the boiler will just sit there not doing much, but you need to have the rad symbol on the control panel to ensure your external controls are calling. without that symbol there you have an control ( roomstat / programmer) fault

As long as you have that, i'd try opening your TRV and lockshields fully open as it could be a lack of flow through the switch.

Further than this you will probably need a RGI to have a look inside the boiler matey.

What are lockshields? all the radiator thermostats are fully open.

Again i must stress that when the boiler shuts off there is nothing displayed in display window except the temperature, no rad or tap icon but when we turn the dial to reset everything displays in the window and stays until the boiler shuts off again.

we have tried the installer again but had no luck

 

[mysteryman]

It is not a flow problem - your controls are not calling for heat for whatever reason. You need the radiator icon in the house.

 

[lmhud]

What do I check for this problem then? could it be the Thermostat? although when I turn it I hear it click but that doesnt mean its working does it.
How would I check it, its a Sunvic

Thanks

 

[Gasman77]

Im with mysteryman, external fault!

 

[lmhud]

So by an external problem do you mean the Thermostat??

I have no idea how to test it, if not the thermostat what else could it be

Thanks