Why is my Mitsubishi Ecodan not heating up the tank?

Can you post a picture of the screen with the error code ?

I’ve just found someone else referring to error code LJ  on moneysavingexpert… their answer was this: We have hot water. Plumber arrived this morning to discover a switch on the pump was not fully on. All sorted now and all fully operational.

 I have a Daikin so I’m afraid that doesn’t mean much to me!! Does it help you ?

Are you able to switch on the immersion heater ?

Is the big 14 on your screen your Target Temperature for the hot water ? The little 14 is the Actual Temperature. Can you increase the Target temperature?

Thanks, I'll check the switches.  Immersion heater is also not working. The big 14 is temperature we set for the heating. The small 14 is the water tank temperature.  Hot water temperature is already set to 50.

There are a few Ecodan owners here: @M.isterW @OrphM62 @Nicllb ??

Will check. Thanks so much 

@juliamc , sorry can’t help as currently we don’t have a tank. Our Sunamp batteries are being swapped out in March. Hoping you got it sorted, as hoping swapping to a hot water tank will solve our heating problems!

Hi, I have the same problem on my Ecodan, how did you manage to solve this?

Hey @hamedj,

Have you tried the above steps? 

@Chris_OVO The thermistors were working fine, and I could see their value in service menu and it was matching the water temperature. However, when it came to the water circulation pump, there was a problem with that. For future reference, there was a slide switch on the pump motor body where it wasn’t fully in position. Sliding that to full on resolved the issue, restarted the system and my water tank temperature raised to 50 in one or two hours.

Hey @hamedj 

Glad to gear you managed to get that all sorted in the end, and thanks for coming back to update us about it!

If you’ve ever got any questions or queries in future, please don’t hesitate to stop by.😊

​@hamedj 

I have the same problem, can you add a picture of what exactly you moved?

Thanks

​@hamedj ​@Mimi 

The installer said that some kind of internal filter might be there and that replacing it would cost about 850 euros. I hope I don't have to do that.

Hi ​@raagraiko ,

I don’t have a photo of my unit at the moment, but if you open your boiler front, you should be able to find the pump above the heat exchanger. there must be a switch on the body of it where you should move it to make it working. Look at the photo below, switch is shown on top. Mine was similar to this.

​@hamedj 

Thank you for answering. 

Mine has been in position 2 for about 3 years since installation. I also tried position 3, but it didn’t help. 

When i restart the device, the flashing LJ light disappears and the boiler starts heating, but after a few hours the error comes back. I probably have a more serious problem. 

Hey ​@raagraiko,

I’m happy to see ​@hamedj has offered some advice. Have you been able to ask your installer about the error message and if there’s any other troubleshooting you can do? 

Hi everyone, 

I have the same issue (LJ error message) and can’t figure out how to solve it. I read the previous posts, i tried the steps mentionned (check the thermistors and the pump) but to no avail.

The thermistors seem to work fine. I can see their value in the service menu, and the temperature rises and drops correctly apparently. 

The pump activates when i restart the system, heats the water for a while then stops, and the error message appears. I tried changing the button on the pump (from 2 to 3 and vice versa) but that doesn’t change anything.

The system heats the water for a while (but not to 50°, it generally stops before that) and then the error appears. I have to restart the system each time I want some hot water…

My installer doesn’t know what’s going on, and must try to contact Mitsubishi directly...

Did anyone manage to solve this issue ?

Thanks.

Hey ​@Jerry05 

Welcome to the community!

I’m glad to see you’ve already tried out the steps mentioned above. As you say, sounds like it’ll be worth checking in with Mitsubishi support directly on this. 

I know others have had to do the same for many reasons and it sounds like they usually have a good experience trying to get what they need from them, so hopefully they’ll be able to help you with this one.

Do let us know how you get on, and maybe some of our community will pop back in the meantime.

Hi, 

Thank you.
As I’m in France (I’m French), I’m going to try to find a French contact for Mitsubishi.

I decided to ask my question here on OVO because I couldn’t find anywhere else someone with a similar problem (same error code).

I will contact my installer again and Mitsubishi if I can.

I’ll let you know.

Hey ​@Jerry05 

I see, still good to have you here!

I did find this page that looks to be France Support specific for Mitsubishi (as long as my Google Translate has helped me correctly) https://fr.mitsubishielectric.com/fa/support.

Do still let us know how you get on, it’ll likely still be helpful to the community!

Hi ​@Abby_OVO , 

Thank you for your help.

My installer should come back to my house some time this week to do a full check on my DHW system, especially the scale trap.
They told me they have a contact at Mitsubishi and should (hopefully) get some answers.

If that doesn’t help, i’ll try and contact Mitsubishi myself directly.

I’ll let you know.

Hi, 

Just a follow-up

The technician came this morning and drained the DHW system and removed the scale trap and the circulator. The problem is definitely limescale.

The scale trap was completely clogged, and the circulator had also started to accumulate limescale... At least now I know where the problem is coming from (water hardness at 28°F).

He was able to clean the circulator a little and ran the trap through the acid about twenty times. After reassembling everything, we recovered some flow. The heat pump heated the hot water to the setpoint, and I haven't received any error messages for now. But he warned me that it won't last too long. I'll probably have to replace the scale trap (pretty expensive...).

He also strongly recommended that I install an anti-limescale system because, without it, the heat pump will continue to clog with limescale quickly (and I'm not going to change the trap, or even the circulator, every two years...).

So I'm going to look into installing a softener, or an Aquabion. I'm not a big fan of softeners, but given the rapid buildup of limescale, I don't think I have much choice. Regarding Aquabion, I've heard about it, but I don't know if it would be effective enough to protect the heat pump.

Do any of you have any feedback on an anti-limescale solution to protect a heat pump (softener or Aquabion)?

Morning ​@Jerry05, I hope you’re well.

I’m happy to hear that the engineer was able to get to the bottom of things for you, and thanks for posting such concise information about this - it’ll help others in the same situation 😁.

I’ve found this web page which has some helpful information, and seems to promote Sentinel products for cleaning and maintenance: https://www.sentinelprotects.com/uk-en/catalog

I wonder whether ​@juliamc might have some advice on this? (Thanks in advance).

No advice from me but now I’m worried !! As far as I know the Daikin doesn’t have a scale trap, but we do have hard water here. Something to investigate.