I have DHW set to come on at 12:00 every day, and off again at 13:55 every day. But today, the DHW came on at 12:00, like usual, but then turned off 20 minutes later and went back to heating. It seems to have done a defrost halfway in, which isn’t too unusual at these temperatures, but it ran quite steady without defrosting for a few hours before, after a very cold night with lots of defrosts. When I got home, i checked the controller and the DHW temp was at 26 degrees.
As it’s gotten colder, I’d recently come up against the 95 min maximum DHW run timer when in quiet mode. But it even then, it still managed to get up to over 40 degrees, even if not up to the target of 44. There are 3 different levels of quiet mode, it was on the middle one, but I changed the level to the least quiet (highest power) quiet mode via the buttons on the outdoor unit. It now has no trouble reaching the target temp in 95 minutes.
Anyone got any ideas? Is the defrost a red herring?
May be coincidence, Jake, but I’m finding a similar thing since my PCB was changed to a vers 01. I tried to monitor what was going on using SNET last time we heated DHW (we only heat a couple of times a week), but the recording failed at some stage (a random comms problem I think), so I was going to have another go. But DHW heating seems to be stopping while still a couple of degC shy of setpoint. Helpdesk suggested setting #5021 (DHW saving temp) to zero, but as I had #5022 (DHW saving mode) set to “off” I didn’t see how this would help. I thought the problem had gone away when I changed #6031 to “off”, but we still got tepid hot water last time.
Check what you have #3025 set to. This is the maximum hot water operating time. I had this set to 95 (its maximum value, default is 30) and my hot water cycles needed to be longer than this in quiet mode level 2. I’ve since changed to quiet mode level 1 and it now completes in around 70 mins.
I have #3025 set to 90 minutes. This should be academic though, as (using the old PCB) it would only take about 40 minutes to heat our (smallish) tank from 20degC to 40degC (all we need for a shower…)
Not quite the same issue but similar if its a timing thing.
I have a similar schedule as you DHW 12:00 to 13:00 everyday and it been like this for 12 months with no issues then Tue18th Nov it started DHW at 10am it did complete and got up to temp.
I checked the schedule no changes and I checked the date and time of the system all good!?
Next day it was back to 12:00 and has been since then…..
Very strange. Could someone have turned it on manually?
I know everyone was out when mine happened, unless one of the cats opened the airing cupboard door (which, importantly, has a door knob, not a handle) climbed up to the control panel and turned the hot water off so they could keep the heating going on the coldest day of the year. I certainly wouldn’t put it past them.
