Vaillant Boiler Overheating (f.20)

hmihajlic

Hi all,

I have a wireless thermostat and 6 smart thermostats on each radiator. I don't have any other radiators in my flat meaning they all have a dedicated radiator thermostat. I also have a Vaillant boiler (ecotec plus). 

When I bump up the heating in all rooms (all 6 radiators) the heating usually works fine. Still, when I for instance turn up a couple of rooms (I usually turn on the living room and kitchen), it heats for a while and then returns the f20 error (which means it is overheating, ).    

I should also mention that I also have a wireless thermostat, which I bought because I needed the wireless receiver (I didn't know that you could buy only the receiver). I don't even touch it most of the time because I don't need it in my setup (could the thermostat be causing the problem?) 

Also, the technician who connected the wireless transmitter used the analog scheme to set it up, although the instructions clearly say my boiler should be set with the 230V relay (could this be causing the problem?) 

The other thing that came to my mind is the fact that maybe the radiator thermostat isn't calibrated the correct way, but as I said - the heating works perfectly fine until the boiler states the error. 

I've called several plumbers to bleed my system because this is the usual trigger for the overheating, but nothing helped. 

Does somebody have an idea how I could fix this?

royi

@hmihajlic you mention you have installed the radiator valves on all your radiators. It is recommended to have at least one radiator without a TRV. This should be the bathroom radiator.

This is for safety mechanism if the other valves failed to open or the boiler reached the desired temperature and activated the heat pump, water would still be able to pump through that radiator without causing damage to the boiler or pump.

This might be causing the F20 error. If this isn't the case you will need to contact Tado support directly.

hmihajlic

@royi thank you for your suggestion! I will try that and let you know the result.

hmihajlic

@royi it worked! I've tested the heating in various combinations on the rest of my 5 radiators (I've kept the one in the bathroom fully opened) for 24 hours straight (actually it's more than that now) - and no errors! Thank you!

But I have a question - is there a way to have all 6 thermostats on all 6 of my radiators? Is the overheating a problem with the setup or a fault in my boiler? 

I've read on the forums that boilers usually have a pass-trough mechanism built in, but it sometimes blocks, causing the overheating. Should I call an expert to check it out? 

I've also read that the timings on the heat pump should be adjusted accordingly. Is this true? 

wateroakley

@hmihajlic Overheating boiler and bypass? Some boilers have an internal bypass, some don't. I'd strongly recommend you ask your questions to a qualified gas-safe engineer who is familiar with your boiler and heating system.