Cobi boiler fires up when thernostat timer is of

[Ste115]

Hello,

I have a new CH system installed with ufh downstairs andradiators upstairs. I have three thermostats, two downstairs and one upstairs.



The issue I am having is that the boiler fires up every15mins or so for around 30 seconds then goes off even when the thermostats areoff.

Any ideas would be most appreciated.

Thanks

 

[Alex Knight]

Have you got the hot water pre heat set to on? What boiler is it? What sort of thermostats are they? What's the setback temp on the thermostats if they are digital?

 

[Ste115]

My boiler does not have a hot water pre heat function. The boiler is a Heatline Capriz Plus, the thermostats are Heatmiser Neo and the setback temp is 5 degrees.

Cheers

 

[Stu Davis]

Are you sure the boiler isnt wired up wrong and in fact it is one and running through the boilers internal bypass. Potentially the thermostats may well be linked to zone valves which are shut causing the small circuit and the fact it is only on for a few seconds. Worth checking wiring to boiler and ensuring there is no switch live even when boiler clock / stats are off.

 

[kris]

what your describing does kinda sound like pre heat function, im not familiar with the boiler but is there a menu function it could be put on or off , otherwise there may be a zone valve stuck open or a problem with the wiring,
Is any pumps on ufh or anything heating up when the boiler fires up ???

 

[kris]

i take its a system boiler lol no pre heat haha,,,, or is it a combi

 

[PhoenixServices]

Get the installer back to check it out, will be under their warranty

 

[Ste115]

I had a look at the wiring centre last night and the only thing that saw which I thought was different was the way in which Zone 1 was wired up (circled in red). I have three of the same thermostats highlighted in green and they are all wired up the same.
Below is the wiring centre diagram and below that is a photo of my wiring centre. Due to the fact that I didn’t have a hot water thermostat the plumber wired it up as below.