Vent Axia Sentinel FH install - am I missing something?

[IGP]

I’ve installed a Vent Axia sentinel FH in my 1930’s semi detached. 
 

Generally all good apart from when firing it up for the first time today, it always goes into boost mode and gives an ‘ls’ symbol when I press boost. Allegedly, the manual says this is because the live switched is making the unit boost, problem is there is nothing connected to the live switched terminal in the unit which is bamboozling me. Am I missing something obvious here?

 

Also, the supply terminals are gushing air (as it’s in boost) but the extracts are a damp squib in comparison. I experimented just venting to the loft for a few minutes but no joy. And I accidentally connected the supply and extracts to the house the wrong way round and the extract terminals were gushing air (supplying) and the supply terminals was a damp squib for extract. So to me, that suggests that the all the ductwork is fine, possibly with the exception of the extract distribution box to the unit as I had to use some flexi ducts as a temporary solution. But given I literally moved them 10cm to swap them around on the spigots, it’s seems unlikely. 
 

Does this suggest the extract fan is a bit dodgy - assuming the ductwork is fine?

 

[IGP]

Fixed the boost issue - stuck it into comfort mode. 
 

Edit - didn’t last long! 

Edited November 26, 2023 by IGP

[RobbieW]

Dont know whether you fixed yours but your description gave me the clue needed to fix mine. Hadnt understood the function of the LS line in, disconnected it and it stopped being in permanent boost - RTFM !!

[IGP]

Yeah exactly the same! I opened the fused spur and removed the LS and same on the MVHR side. Worked straight away and now living my best MVHR life. 🤪