L9 error ecodan

[yb900]

Our ecodan started with an L9 error a few days ago and I cannot seem to find the problem.

 

The pressure was at about 1.2 so increased to 1.7. This didn't solve the problem.

 

The hot water is working fine and the tank is heating up no problem on schedule but the heating upstairs (rads) and downstairs (underfloor) will not work.

 

I followed the advice of the mitsi youtube videos and had a look at the filter. When letting out some of the water there is a little black debris. Flow rate is at 0!! It just happened all of a sudden in Thursday morning. Pump speed was/is set to 5.

 

Any ideas what else to try? At this point I'm stumped and calling out the engineer, but I hate not being able to fix it myself!

[MikeSharp01]

The ecodan must be working if the water is heating unless the water heating is done by something else? E.g. immersion heater. If it is heating the water I would look at the changeover valve(s) - maybe it is stuck in water heating mode and the HP is getting a good go signal for that and the error only occurs when heating is requested but it does not get the positional feedback from the valve to say it iss ready to direct the water round the heating. 

[LA3222]

Do you have any y line strainers installed? Xouple of years back I noticed flow was really low, eventually thought to check tge strainer to find it was gunked up - flow improved a lot once I'd cleaned it.

[trialuser]

The ME Engineer app gives this for L9