@mike-patrick it looks as if your pump is in a local hollow, does the cold air from the pump hang around there or does it dissipate? Have any of the experts you’ve used to try to improve the performance suggested this is a factor?
2kW + Growatt & 4kW +Sunnyboy PV on south-facing roof Solar thermal. 9.5kWh Givenergy battery with AC3. MVHR. Vaillant 7kW ASHP (very pleased with it) open system operating on WC
No-one has suggeted that although I've checked myself that the exhaust air is clearing the ASHP. It's not so much a hollow as a gentle slope of the garden border at that point - looks worse in thge picture than it is. It is on the north side of the outbuilding so rarely gets direct sunlight, except in the summer months when the sun is overhead. Unfortunately it wasn't possible to site it elsewhere..
It is now running on what Heat Geek's Adam Chapman calls 'Pure Weather Compensation' and Daikin call 'Leaving Water Temperature control' on a 'home made' design temperature of 38º @ -3º . Today it was -3 when I woke up and the house is a comfortable 22º. I'm fairly sure it will cope with 37º @ -3º if not 36º.
Just to say I did read this post before joining the forum and it inspired me to start looking up the LWT mode. I had seen the Heat Geek Daikin MMI video but didn't know exactly what pure WC meant in the Daikin context. Using Grok to search for LWT through the various online manuals I had a rough idea what menu options to look for.
LWT enabled. Schedule re-enabled to allow a -2C night time setback (no target temps allowed). Changed the Octopus 50C @ -3C to 45C @ -3C. Next morning house was still warm enough but the HP started at 4am which I didn't need. So I tweaked the slope a bit more to the left and after a reset the HP stopped.
I'm surmising the Daikin heat pumps don't run below 25C LWT so if you set the slope at any point to a calculated LWT of 24C or below the HP stops. You should be able to go back to the "Main Zone" to see the calculated LWT but it seems to need a reset to apply the new slope. Temps much to mild still to any more fine tuning.
@bimbleuk According to the Daikin manual, (I have the 8 kW EDLA03 monobloc), the minimum LWT [or flow temperature] should be at least 5 degrees C above required room temperature. In my case (we enjoy a room temp. of 22.5 deg. C., this would be a LWT of 27.5 deg. C. as a minimum; as it happens, our system has a set flow temperature range of 30 - 45 deg. C. and of late, we are running (via Homely controller) at ~32 to 34 deg. C. Regards, Toodles.
Toodles, heats his home with cold draughts and cooks food with magnets.
The attached chart shows the salient readings for today so far (taken from the Homely Installer’s ‘Connect’ app.), so far, the cooler weather has not impacted on the heating demand as much as previously to fitting the triple glazing throughout. Am hoping for lower energy consumption this coming winter. Currently, we are seeing a COP of ~5.2 - 5.4 typically. I hope I have not plonked too many parameters onto the chart for clarity. Regards, Toodles.
Toodles, heats his home with cold draughts and cooks food with magnets.
@toodles Useful reply and because Heat Geek mentioned it in the Daikin MMI vid I didn't do any further checking. Using Grok again to sift through all the online data there may be a mix up of a 25C minimum LWT for efficient hot water heating. There is an anti-freeze mode for temps below 15C so does look like it can go lower but as say there is some guidance to minimum settings relating to the desired room temps. So yeah some more playing required.
Also a red herring was my LWT was 26C when I was playing the first morning and the HP just happened to stop when I adjusted the slope and it dropped to 24C!
JT
This post was modified 2 weeks ago by RadWhisperer
I think it's worth adding here that when you enable the Daikin LWT mode the pump switches from demand/request to sample. That means the pump will cycle on and off periodically to more accurately measure the average system water temp. At first I was hearing a rushing noise periodically at night and initially thought it was the neighbours new loft boiler install. However it persisted and was getting annoying as it was very distinct.
Anyway after the usual Grok query of the online manuals I learned about the sample mode and the possibility of a menu option to alter the pump speed. Sure enough I found a setting and changed the default 80% (excessive) pump speed to 60% (observed 15 l/min drop to 10 l/min). Now almost silent and I checked that there were no flow errors triggered.
