Viessmann capacitor missing

eagleeye · Oct 14, 2020

Just been to one of our installers jobs because customer said boiler wouldn't go off when the heating was turned off on the Hive. It's a heat only 100 series boiler. So I turn on the heating on the Hive and boiler comes on but when turned of boiler keeps running. I take off hive receiver from backplate and boiler goes off and 3 port closes to hot water. Put it back on and try Shaun to test when off my white of motorised valve is dead and all good but still 240 at switch live. But if I test between neutral and switch live the boiler shuts off. Strange. I've replaced the Hive so know it's not that. Could it be that the installer took out and through away the capacitor that should be between neutral and switch live #1

Chuck · Oct 14, 2020

This part of your question:

eagleeye said:
Put it back on and try Shaun to test when off my white of motorised valve is dead and all good but still 240 at switch live. But if I test between neutral and switch live the boiler shuts off.

is incomprehensible to me. Maybe if you sketch a diagram you can refer to and also be explicit about what you mean by 'test' (voltage, current, resistance, jumper, etc.) I, or someone else, can help.

This may not be relevant but some of the most puzzling behaviours I've come across have been down to floating neutrals. There's been just enough capacitance between neutral and earth for low current devices to sort of work...

It seems unlikely that an installer would remove a component like a capacitor unless the they'd been told to, e.g. by the manufacturer's tech dept. IME, installers who've had any training at all know the importance of sticking to the MIs.

eagleeye · Oct 14, 2020

Chuck said:
This part of your question:

is incomprehensible to me. Maybe if you sketch a diagram you can refer to and also be explicit about what you mean by 'test' (voltage, current, resistance, jumper, etc.) I, or someone else, can help.

This may not be relevant but some of the most puzzling behaviours I've come across have been down to floating neutrals. There's been just enough capacitance between neutral and earth for low current devices to sort of work...

It seems unlikely that an installer would remove a component like a capacitor unless the they'd been told to, e.g. by the manufacturer's tech dept. IME, installers who've had any training at all know the importance of sticking to the MIs.