Daikin Altherma ASHP and no hot water

[M550344]

I am new to this forum as well as using a ASHP and I am hoping someone may know the answer for an issue i am experiencing with our installation. I have a Daikin Altherma EDLQ07CAV3 and a Daikin 250l HW tank that was installed in Jan 2023. What we are experiencing is that during cold weather spells e.g 0C or below the ASHP stops heating the HW and we are reliant on having to use the immersion to maintain the HW tank temperture. CH is not an issue and is working as expected. As an example, normally the ASHP will maintain HW at around 45C day and night, but when we have low temperture days the ASHP will not heat the HW and the tank will lose heat over time until we use the immersion to re-heat the water. Octopus who installed the ASHP have yet to resolve the issue, including getting the disinfection cycle to work, as the ASHP cannot heat the HW beyond 48C, and it will just sit in disinfection mode trying to get to 60C until the system gives up and reports that it could not complete the cycle.

 

As an example disinfection is scheduled to come on at 4:00am in the morning targeting 60C for 30minutes when no other demand is expected. When it attemped to carry out the cycle yesterday and again today, during the cycle the HW tank actually dropped in temperture, and between 4:00am-7:00am at no time did the ASHP attempt to heat the HW e.g remained off the whole time. Eventually I cancelled the cycle as it was clear it was not going to work.

 

There is definately a correlation between HW heating not working and cold tempertures, but as yet the issue has not been resolved. Would appereciate any guidance forum members maybe able to contribute.🙂

[JohnMo]

Sounds like setting issues .ore than anything else. Time to get the manual out and read a few times until it makes sense.

 

Do you use most your hot water each day - if so you don't need to disinfect.  Heat Geek have a good write up the subject, with the risk etc.

 

Heating you cylinder from 48 to 60 will take over an hour with a 3kW immersion.  If you want to hold that temp for 30 mins you need to set to 1.5hrs run time. But if the immersion isn't heating there an issue, it's tripped on over temperature and needs to be reset or it's thermostat is set too low so it's not starting.

Edited January 10 by JohnMo

[M550344]

Thanks for your feedback. There is definately a setting issue here for HW that is preventing ASHP from heating HW when temp is 0C or below. Time for more reading

[sharpener]

Can you check if the diverter valve is moving to the DHW position when it is supposed to be heating the HW? If so it is perhaps a performance issue, if not then a control problem.

 

Personally as @JohnMo says I would not worry about the legionella cycle in normal everyday use unless you are immunocompromised or something. But a useful stick to beat Octopus with and get them to deliver on their contract.

 

What is the refrigerant in this HP? What max temp is it supposed to be capable of, and so will it need assistance from the immersion to achieve anti-legionella temp?

 

Is there a Daikin user group on FB like there is for Vaillant?

[HughF]

Daikin are usually running 410a in their older models of altherma, moving to 32 in the newer ones.

 

I’m in the ‘disable legionnaires cycle’ camp… don’t think my heat pump even has a feature for that.