best wishes

Over the last few days, I decided to contact a professional to take a look at my heating installation to see if they could resolve the issue.

They ended up cleaning the same filter you had mentioned earlier (I wasn’t aware it existed), and it was indeed full of rust!

Previously, I had a mix of aluminum and iron heaters in my system. After noticing that the iron ones were rusting, I replaced them with aluminum ones and cleaned the filter I sent earlier, thinking it was the only one.

Now, my heating system has been running the entire night without any errors, so I believe the problem is resolved. However, I wanted to wait a bit longer before posting to confirm it’s fully fixed.

Additionally, my system had : 

, but it seems it didn’t prevent rust as expected. I’m quite disappointed in its effectiveness.

Thank you all for your help, and Merry Christmas!

hi Michel. The L9 fault is specific to a problem with the flow rate registered by your flow meter.

If the flow rate drops below the usual minimum (which is 5 litres per minute) then the L9 error is reported and your heat pump will be shut down.

I also said in an earlier message you may have more than one filter fitted and both may need to be cleaned out.

you have since sent a picture of your equipment schematic.

I can see you have a Mitsubishi Hidrobox which is a pre-plumbed cylinder and pre assembled system. You will have a Y-strainer built in to this box located at the back. This is where all the limescale, rust flakes and radiator scum will collect and if you haven’t emptied it in the past 2 years you will probably have a problem with it being choked up and stopping the flow of your heating system.

please let me know if you can locate this component and if it can be isolated or sealed and then the filter chamber opened.

IMPORTANT - did you put rust inhibitor chemical in the water when you filled up the heating system? I ask just to be 100% sure.

I attached a picture of how it looks on your assembled hydro box. Make sure you shut the taps before you try to unscrew the filter nut…. That’s very important.

you will get a load of bits that look like this inside the mesh filter.

Or even bigger bits like this.

Michel, its important to reply so we can be sure you have been helped. Thanks in advance.

And Merry Christmas….

Have you contacted Mitsubishi support in France?

I have done all the plumbing myself. This is the diagram that i followed :

My flat is around 100 square meters and it is normal if it is in french because I live near Paris.

I used the PAR-WT60R-E with the associated PAR-WR61R-E, and i didn't forgot to put the switch SW1-8 on the on position.

I'm unable to tell you if by enable the pump manually I still get the flow error because by doing so just the pump starts and there is no heating.

Finally the filter that I cleaned looks like that and i was pretty cleaned. Like i didn't saw any suspicious things

Recently, I decided to install a Wi-Fi remote to monitor the temperature in my living room and control the heating more efficiently

Did you use the Mitsubishi PAR-WT50R and if so after connecting the cable to the FTC,  did you also set the appropriate dip switch in the FTC to on - I think it is SW1-8?

but if you’re having to manually activate the circulator it sounds like it’s not set up properly. 

your language setting is set to French. Is that ok for you? 

With the Mitsubishi system your circulator pump is the only pump that moves any water. There is no internal circulation pump inside the heat pump itself. In normal operation the circulator starts first before any heating takes place and this is fully automated when set up properly.

If you can give a full description of everything you’ve got installed including emitters and house size you will get the best advice on this forum. 

my initial questions

Do you have the Mitsubishi pre plumbed cylinder? If not you probably can’t control circulator speed via the ftc controller. You will need to change speed on the circulator itself (push button)

What filter did you clean? There’s a metal deposits filter and there should also be a wire gauze strainer somewhere?

Who designed /installed it all? They may advise on how it’s set up.

I hope this helps so that this group can help you further…