@terry1812 We have a Daikin EDL03 8 kW monobloc Altherma 3 and that does have variable flow rate but usually sits around the 15 lpm mark - going up to ~30 lpm on occasions. Regards, Toodles.

@toodles , you are using homely aren’t you, and I believe it’s the homely that is controlling the flow rate, is that correct. I tried to contact homely to talk about that but couldn’t get anywhere. Did your installer put in the homely? Would they discuss it with me do you think?

@terry1812 Yes, I use Homely, as to whether Daikin is unable to control flow rate without, I don’t know but it sounds strange if that were the case. I have no idea if my installers would be able to answer any questions but they are Cinergi. Regards, Toodles.

@toodles , thank you so much. Spoke with Cinergi today, they were very helpful and are hopefully going to do a technical appraisal of my system. Feeling a little less stressed now!

@terry1812 Oh Good! Pleased to help if I can! Regards, Toodles.

Ive called most of them over the years. By far the best seems to be Panasonic, very helpful, calls back if needed and parts required next day delivery. Mitsubishi also been good but can take longer to get through, Daikin similar, Samsung varies, Fujitsu pretty good too. Worst has been LG and parts often obsolete before 10 years old. Most distributors have a decent tech dept.

This is regarding an annual service review by Mitsubishi - overall a negative experience:

I've been struggling with the heating and felt that the heat pump (Mitsubishi Ecodan 8.5kW) was not performing well for some time. It was installed in Jan 2023 and had my first service this year by Mitsubishi (missed 2024 due to lack of cash). I used the manufacturer directly to get a different view rather than using the installers offer of paid annual service reviews. I've had various concerns around the defrost functionality and it was a struggle to get one room to a good temperature. I ended up increasing the temperature offset to +5 which did help. The installers also did some customization work to integrate to Hive devices to control the heating. 

The report never turned up. I contacted them via email and didn't get a response. I finally spoke to someone after 2 weeks trying occasionally to be told the report was just in a queue and hadn't been touched due to them being short staffed. After waiting a month and now with the report I contacted the installers regarding the issues raised.

There were several issues however the only real performance one was:

Low Flow rate at 9L/min (many L9 errors) - caused primarily by the reduction of 28mm pipework from the heat pump to the orginal 22mm boiler pipework then back to 28mm where the cylinder/controller/heating junction is.

I spoke to the installers about all of the report and they answered everything in detail:

Low Flow rate at 9L/min - particle filters are likely blocked and should have been cleaned by Mitsubishi the engineer. They had not touched these, I was only aware of the magnetic filter myself but the installers told me where they, provided a video and after I cleaned them the flow rate was at 18L/min. I'll clean them again and the recommended replacement pipework is no longer needed.

The other issues required more information from Mitsubishi being requested from the installers as they were challenging everything mentioned. 

Based on my previous conversation with Mitsubishi I doubt I'll get any answers quickly however I certainly will be trying to raise a complaint around this annual service.

Posted by: @cold123456

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The installers also did some customization work to integrate to Hive devices to control the heating. 

Bit of a concern here.  Hive and heat pumps don't really play well together.  External controls, other than the few specifically designed for heat pumps, are, in most cases, best avoided other than as temperature limiters, ie turned up a couple of degrees above target.

@jamespa Indeed they are; we had a NeoStat device as this I think was the default device fitted by the installers. The first thing I did was set the thermostat 2 degrees above maximum required and set the WC controls in the MMI to do the job. As soon as it was available for the Daikin model we have, I had the Homely controller installed to do the job. On-Off thermostatic devices are a real killer to heat pumps! Regards, Toodles.

@jamespa These may well be removed in the near future but I'll need to discuss the options for the two zones as it's split using the hives rather than the controller. The hive settings are a specific temperature in the day time, control of one zone (extension that is insulated from the rest of the house) which doesn't need to be on everyday, then overnight introduces a small decrease in temperature for weekdays. The installers have highlighted an issue around the hives even though the designer suggested they would be better than the manufacturer options:

"Hive thermostats were wired to provide the previously mentioned run signal to the heat pump from 2 zones, when there's no demand from either the heat pump and circulation pumps are blocked."

"Frequent on/off cycling by 3rd party thermostats can sometimes cause poor performance as the unit is cycling on/off unnecessarily with the 3rd party thermostat logic. This link can be taken out or disabled so the heat pump only follows the heating curve."

It has been working well enough with the increased offset but with the flow rate change I'm hoping I'll see large improvements and will adjust accordingly. I don't know how long I've had this flow rate issue but it may have been the main issue. 

Missing the first year service was a mistake on my part which might have highlighted the flow rate issue earlier but at least I can deal with the filters directly now that I know about them. I've been wasting my time looking at the magnetic filter every 6 months as it's just been clear each time.

Posted by: @cold123456

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but at least I can deal with the filters directly now that I know about them. I've been wasting my time looking at the magnetic filter every 6 months as it's just been clear each time.

Fwiw I called my installer out for the first time a few weeks ago for a mix of odd faults.  Like you I had cleaned out the mag filter.

After a few minutes at the controls he went straight to the equivalent filter on my Vaillant system and cleaned out a load of black gunk.  He said that 90% of his call outs are for that filter!  I didn't even know it was there.  Needless to say it fixed the problem.

You are obviously conscious of the possible issue with hive so I won't say more other than to suggest you may wish to think about whether you really need 2 zones or alternatively, if the extension truly is isolated thermally, whether you could switch that on and off whilst running the rest independently of the hive.