You’ve come to the right place, @Whitwop. 

A lot of forum members here have ‘compensation curve’ as their middle names and may be able to advise… @Ecodanwarrior @dgamble731 @James_N @christianedward @hambrook @Speps @fox @M.isterW - sorry for the spam tag but I know some of you don’t mind chatting about this stuff...

Hello.

I didn’t quite understand what exactly you saw in the MelCloud application - an error or a normal state indicator. So a good place to start is by looking at the error log. This can be done using the wall-mounted control panel or the MelCloud app (error report).

Additionally, if you have an SD card installed in the Ecodan module, you can extract it, copy the data to your computer and visualize it using special Mitsubishi software "Ecodan SD Tool FTC4" or "Ecodan SD Tool FTC5" (only for Windows). FTС version is indicated on the nameplate of your Ecodan controller. In the program interface you can see all the states of your pump, temperatures, errors, etc. I will attach an example of such graphs below.

The documentation "Mitsubishi Electric Flow Temperature Controller (PAC-IF061B-ER2, PAR-W361MAA) - Installation and Operation manual" describes a some related errors:

Code: P6
Error: Anti-freeze protection of plate heat exchanger
Action: See Action for L3. Check for correct amount of refrigerant

Code: L3
Error: Circulation water temperature overheat protection
Action: Flow rate may be reduced check for;
• Water leakage
• Strainer blockage
• Water circulation pump function (Error code may display during flling of primary circuit, complete flling and reset error code.)

Code: L6
Error: Circulation water freeze protection
Action: See Action for L3

Probably, the issue is not errors, but the fact that the antifreeze function ("Freeze stat function" as docs say, i think?) is turned on forcibly, so as not to damage the heat pump, even if this option is turned off. I did not find confirmation of this in the documentation, but it sounds reasonable.

You can also try to look at the temperature sensors (via the wall-mounted control panel or from the SD card) and look for the refrigerant temperature there at TH2 thermistor value. 

It is also worth keeping in mind that the thermistor can fail completely or partially, and SOMETIMES show incorrect data, which is why the system will work, but unstable. You can quickly and efficiently check all thermistors and historical indicators only using an SD card and a program for reading data from it. Wall-mounted control panel can also show this data, but only for the current moment.

And, the last but not the least, maybe, you just saw “defrost” function running? This is completely normal.

Ecodan SD Tool - thermistors data example:

Ecodan SD Tool - state data example: 

Compensation curve is a very simple, and, sometimes, litte complex thing. Correct settings is specific for your conditions, so it is impossible to say what exactly you should set up. 

Forum has a lot of related stuff here.

Also, you can look at YouTube.

Try playing with the settings of this option yourself, don’t be afraid, you won’t break anything.

If your heat pump starts to frost up (ice covering the heat exchanger) it will run a defrost cycle. This melts the ice to allow air to get through the fins on the heat exchanger. This might be what's happened. You can't change settings to stop this happening, and you wouldn't want to.

Thanks for all this.  It is just that on the melcloud app, on the radiator bit where it normally says "idle" or "heating" it said "antifreeze" and both pumps,  heating and primary came on.  I'll work through your very kind reply and try and put my mind at rest. Thanks

How do you turn off the antifreeze setting? Glycol has been added to the system. Last few days I'm seeing it has activated and I would like to turn it off.

Hey @FredE 

Great question!

As this isn’t our own equipment, I’m not entirely sure myself. I did have a look online, through some other forums but had no luck finding how to do this.

It might be worth contacting Mitsubishi themselves, or if you’ve still got the manual, it may be in there? 

In the meantime, hopefully some of our heat pump users might have an idea?  @Ecodanwarrior @dgamble731 @James_N @christianedward @hambrook @Speps @fox @M.isterW

Hi @FredE 

I recently was looking into this myself as with the drop in temp what I can only presume is the antifreeze function has started to kick-in.  The builder has said that Glycol has been added to our system but I’m not sure I trust them 100%.

But anyways, to turn off the anti-freeze function you need to go into the service menu, go to Operation Settings, and the option to turn it on/off is in there.

pg 36 of this manual also has information on it - Ecodan FTC6 PAC-IF07(1-3)B-E Installation Manual (BH79D843H02) - Document Library - Mitsubishi Electric

@FredE Hi. You can use your remote controller device to configure/disable this function. Look at scheme below.