Hot water and heating control with my Mitsubishi Ecodan Air-Source Heat Pump (ASHP)?

The report posted by @jason.lewis in the COP thread doesn’t mention much about hot water heating but does suggest schedules can be used to good effect. I’ve changed my to a schedule but that’s partly because I have my immersion connected to my solar PV and any excess electricity gets dumped to the tank. My water COP isn’t good but I’m also not heating my tank very often. 
Does the Mitsubishi system allow a schedule and reheat option? On the Daikin you can set this up so that it’ll run a schedule, say 48C at 10pm, which only kicks in if the immersion hasn’t heated up the tank or we’ve used the hot water.  Then we have reheat during the day if water temp drops low, in the Daikin case 10C less than what you set it at, so my day time reheat temp is 45C, so if tank temperature drops to 35C it boosts it back up to 45C. 
I don’t personally see the benefit of an eco7 type tariff. The hot water demand isn’t enough of overall electricity usage to warrant the increase peak rate you pay when heating is required, at least through the winter.

thank you @Speps . Another question seeing as we seem to have the same system. Do you know how to navigate the menus to adjust the legionaires cycle? Mine is set at 7 days and i wanted to extend it to 10 days

@James_N yes on the controller hold the bottom left button until the menu options change colour. From there click hot water, and the pencil icon on legionella. Try to resist changing other settings but do have a look what your tank set and reheat temperatures are.

Thanks @Speps   Mission accomplished. Hot water is set to 50 degrees with a temp drop of 10 degrees 

@James_N @hydrosam and @Speps, would anyone object if I moved this topic into the public Smart homes forum category? I think this might be helpful to heat pump owners even if they’re not on the trial…..

No objection here. The original question was about how to control this on the Mitsubishi system. I don’t whether it’s worth mentioning that? The Mitsubishi Ecodan does appear to have more flexible controls and an easier to use interface than the Daikin. 

Good point, @hydrosam - I’ve now specified the Ecodan in the title and tags so this thread is nice and specific now. 

I’ve also spotted a very nice summary of the settings available. posted by @Speps on this private Smart trials thread:

“The ecodan has 3 options for heating: fixed flow temperature (always the design temperature) , weather compensation mode (variable on air temperature and following the weather compensation curve) and target room temperature mode.

I understand the target room temperature mode uses the indoor temp sensor and the outdoor units temp sensor to calculate the real time heat loss, and adjust flow temperature from there. The building’s rate of heat loss is variable but more consistent than the air temperature, so should be most efficient way for the heat pump to maintain room temp.”

I feel like this is a big subject, with lots of variables that influence which option to go for. So it’s nice to have somewhere specific for the Ecodan. 

I’m already kinda of relieved to find this forum / post because I too have an Mitsubshi EcoDan ASHP fitted 3 weeks ago and the installers have pretty much fitted it and forgotten us.  I was rushing to get the RHI in before the end of the month and I’ve already let them of the hook by paying but I don’t think there isn’t much that can’t be sorted out without some education.

The main problem is that the hot water tank is right next to our bedroom so it wakes us up in the night and tends to stay on for a couple of hours. I've worked out most of the controls but despite setting of timer to switch the system off at night it still sometimes comes on for no reason that I can see.

I know we can power off the system to stop it completely but then of course it doesn't give us heat or water until we switch it back on and I'm worried that the anti freeze system I've seen also can't work when it's powered off. Last night it was warm both inside and out, tank temp was high enough and the timer was off until 7:30am yet at 6am it kicked in, no idea why.

I need some help please.

Hey there

I’m afraid I’m not much of an expert in ASHP stuff myself, but I can ask my friends to stop by. I know @hydrosam is definitely an expert here! I’ll see if there’s anyone else I can ask too. Bear with us!