The unit is programmed to start legionella every 2 weeks at midnight, however, for some strange reason it comes on anytime and around 3 or 4 times every 2 weeks. Even stranger is that it doesn't actually heat up the water, you can see over time that the water temperature drops from 49 to 16 Celsius. One time I tested the water temperature with a thermometer, it displayed 17C on the system screen, but the actual water temperature was 46C, however the water temperature does drop over time.
The system will be stuck on this mode for around 2 days, and during those 2 day I won't have any heating or hot water. The system doesn't consume any additional electricity during this mode.
@ak2024 - that symbol is immersion or boost, not legionella - see:
Also I assume your probe is mid-to-lower in your cylinder so it will only show 46C shortly after a DHW heating cycle - the lower stat will show lower the longer it is from a cycle / the more hot water you use (cold water ingress mixing with hot water in lower part of tank cools it).
If your cylinder water is always hot I'd suggest the cylinder probe is faulty or not tight into the cylinder, though I can't explain why it happens every two days.
If your outdoor unit (OU) isn't heating the water suitably (can't heat, flow too high, other fault), the immersion will kick in to try and give you hot water. Perhaps monitor the OU going forward too.
@rhh2348 During Normal operation everything works fine, the temperature reading goes up and down as normal, it's only roughly after 2 weeks this happens. It will be stuck like that for 2 days and after the 2 days everything is back to normal again. Also, nice catch with the SD card symbol being black.
Do you know your immersion/booster actually works as it should?
Check your legionella prevention settings to see when it's next due to happen and see if it co-incides. You can bring this forward to tomorrow if you wanted to test quicker.
Check the DHW + legionella settings - e.g. max. operation time
Check your error history on the main remote controller (not sure if you need to sort your SD card out first!)
The company that installed the system seems to have unticked the legionella setting during their recent visit. However, they told me it was supposed to come on every fortnight at 00:00.
Two days after their last visit, the system got stuck in that mode. The DHW works fine until it gets stuck in that mode.
The DHW comes on between 10 p.m. and 12 a.m., 4 a.m. and 7 a.m., and 1 p.m. and 4 p.m. during off-peak hours.
Even if the DHW coincided with the legionella cycle, the legionella would have overridden the DHW. The water heats up in 30-40 minutes, so the DHW wouldn't be on at 00:00.
If there was some sort of conflict with the timing, I don't think it's normal for the system to get stuck in that mode. Also, when the immersion symbol is on, it doesn't actually consume any electricity.
The biggest issue is that the company that installed it is not taking any responsibility. There was bad wiring and poor plumbing, but they repaired that. Another issue came up after the last repair: when I switch on the underfloor heating, the master bedroom radiators come on, which they are not supposed to do. All the other radiators stay off, just the master bedroom ones turn on.
The company that installed the system seems to have unticked the legionella setting during their recent visit. However, they told me it was supposed to come on every fortnight at 00:00.
If the legionella is unticked I doubt it'll come on as the installer states.
The DHW comes on between 10 p.m. and 12 a.m., 4 a.m. and 7 a.m., and 1 p.m. and 4 p.m. during off-peak hours.
In your first photo it's not on timer - it's running continously. This means it will only kick in when your DHW temperature drops below the max drop setting.
If there was some sort of conflict with the timing, I don't think it's normal for the system to get stuck in that mode. Also, when the immersion symbol is on, it doesn't actually consume any electricity.
Are you using the FTC consumed figures for that? If you haven't set your immersion heater capacity in Energy monitor settings, it won't show usage.
If you run a legionella cycle and it completes within reasonable timeframe, it's not your immersion - you could also test this by setting your 'Heat source setting' to Heater. That would negate any issues with the immersion/booster.
The biggest issue is that the company that installed it is not taking any responsibility.
It wasn't set on timer before, but it is now. I've told the engineers about it being stuck in that mode, and it felt like they didn't believe me, even after showing them the pictures. I told them to manually switch on the immersion heating and to check for themselves, but they won't do it, because I think they don't know how to manually switch it on.
Anyway I'm waiting for it to go back in that mode, so I can complain again, I have to also tell about the master bedroom radiators heating when it's supposed to be just the underfloor heating.
A quick question, when you turn up the thermostat, how long does it take for the Ecodan air source pump to come on? My one comes on after 5–10 minutes, even when I change the temperature on the hardwired thermostat.
@ak2024 I suspect there are actually degrees of ‘coming on’; I know when I make a manual request to my Daikin pump for heat that there is a delay of a few heatless moments. The system takes the request for heat and starts the heat pump water pump and the circulating pump also starts up, this runs for a minute or so and I assume that this is to allow the system to check the LWT has stabilised at which point, the system accepts there is a need for heat and starts the compressor gubbins - heat takes about 10 minutes to be evident in the radiators. That’s my experience and reasoning anyway. Regards, Toodles.
Toodles, he heats his home with cold draughts and cooks his food with magnets.
Thinking about installing a heat pump but unsure where to start? Already have one but it’s not performing as expected? Or are you locked in a frustrating dispute with an installer or manufacturer? We’re here to help.
