Problems with Daikin 18 kW High Temp ASHP - Air Source Heat Pumps (ASHPs)

RE: Problems with Daikin 18 kW High Temp ASHP

Bramshot — Fri, 12 Apr 2024 10:36:33 +0000

@haggistrap I have no idea what the COP is mine does not tell me anywhere.

The HP is effectively on most of the time. I only use Heat on Demand for a couple of the TRVs, the ones with the Highest demand. The room stat schedule is mainly used for part of the day where I want to make sure the heating is on to get a boost during my off peak electricity period ( 00:30 to 04:30) when hot water has done for the day, so there is no heating required for a while and my battery lasts a bit longer in the on peak time.

RE: Problems with Daikin 18 kW High Temp ASHP

Terry Nolan — Fri, 12 Apr 2024 08:51:26 +0000

Just curious on COP. Mine is sitting around 3.3 -3.5 with outside temp 8 to 10c. Don’t want to get in to mine is better than yours but I think that’s about standard, or rather it looks acceptable.

I just leave my hive On, I.e. it’s just an easy way to zone / schedual heating on/ off. TRVs set to max mostly through house, with bedroom ones limited to around 19 20c.

set ASHP to weather compensation mode now.

if any one interested, the gas report from engineer came back. It was missing 840g of R32 gas. Now it’s back to 4.2kg of r32. Time will tell if it helps.

RE: Problems with Daikin 18 kW High Temp ASHP

HCas — Fri, 12 Apr 2024 08:40:10 +0000

@bramshot Interesting! Do you know what COP you get?
I'd imagine you prioritise control over minimal cost then?

RE: Problems with Daikin 18 kW High Temp ASHP

Bramshot — Thu, 11 Apr 2024 17:00:22 +0000

@hcas I use schedules both with the wall stat and TRVs.

RE: Problems with Daikin 18 kW High Temp ASHP

HCas — Thu, 11 Apr 2024 14:05:34 +0000

@bramshot Interesting work-around you created with Hive, smart!! It still remains an on/off control, but you've essentially reduced the number of on/off cycles.

Did you also set a schedule in Hive?

Are you using the smart TRVs, or just the thermostat?

RE: Problems with Daikin 18 kW High Temp ASHP

Bramshot — Wed, 10 Apr 2024 16:30:21 +0000

@haggistrap Mine is ok until ambient gets down nearer freezing, say sub 4 degrees. Be interesting to hear how yours performs with a full charge of refrigerant but I suppose we will have to wait until next winter to find out now! I wonder if they will put it out as something that should be checked on all units?

RE: Problems with Daikin 18 kW High Temp ASHP

Mars — Wed, 10 Apr 2024 13:53:36 +0000

@haggistrap at least they've found the potential source of the issue. Fingers crossed that this will solve the issue. Keep us posted and updated.

RE: Problems with Daikin 18 kW High Temp ASHP

Terry Nolan — Wed, 10 Apr 2024 13:48:13 +0000

Update on my Daikin HP.

so, apparently a number of these Daikin HT ASHPs were sent to the UK with insufficient refrigerant gas. Today, My Daikin engineer took all the gas out, weighted it and it was significantly low on gas. He and the Tech specialist think this is why my unit hasn’t been performing as it should.

The unit is now heating back up, took around 4 hours to complete the weigh gas and refill.

I had noticed even in warm temps I.e. 8 to 12c my unit will still run defrost cycles, so I’m hoping not to see that behaviour over the next few days. Though next winter may be the test in reality to confirm if the correct gas level will sort it out.

anyway a bit of optimism now 😀

RE: Problems with Daikin 18 kW High Temp ASHP

Bramshot — Fri, 08 Mar 2024 13:08:22 +0000

@toodles Hive is working fine for me after the mods I did. However, I agree it would have been useless without it. Hive do not actually recommend its use with HPs.

RE: Problems with Daikin 18 kW High Temp ASHP

Toodles — Fri, 08 Mar 2024 10:57:07 +0000

@hughf When I was researching what, which, where, how and why for fitting an ASHP and ridding ourselves of a starting to fail gas boiler, I asked potential installers about utilising my existing Hive boiler interface, controls and TRV’s. They said ‘No’ not at all suitable for this. I have still used one of the Hive TRV’s on the bedroom radiator as I wish to have a programmed change in temperature at night. There may be better TRV’s around perhaps but I already had this one and it serves for this purpose. The installers supplied a NeoStat controller which is as crude as they come ON-OFF! I now have the smart control by a Homely controller - much better! Regards, Toodles