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I have the same problem occasionally with my Panasonic Aquarea 16kW A2W heat pump running UFH in Portugal.

It would throw either H62 - 'Water switch abnormality' indicating the flow rate is too low, or H12 - 'Indoor/Outdoor capacity unmatched'.

The H12 error is the most annoying - it basically means the unit has been unable to wind down the output capacity enough to maintain the flow temperature. It should have stopped the compressor, but these units are too clever for their own good.

I think the proper solution to all this is that there should be a buffer tank between the heat pump and the UFH. What I did was ensure there was a kitchen radiator always open in the loop, and use the low/normal/boost settings on the app which change the flow temp - 35C / 40C / 45C depending on the time of year.

When I installed a Kensa 25kW GSHP in the UK, I separated it from the UFH with an 800 litre thermal store. The Kensa units are also so simple that they are either on or off - no errors here.

A low loss header is a sort of mini buffer designed specifically to get around this problem, although they were originally designed for use with boilers and multiple circulation pumps. Dead simple, just a fat bit of pipe with two pipe connections at the top and two at the bottom, that's connected inline with the flow and return. This is a good article describing them: https://www.heatgeek.com/low-loss-headers/

The big advantage over a buffer tank is that they don't take up anywhere near as much space.

House had crept down to 10 degs in.last few days so had a fair heatsoak to do. Ran most of the SH's while we were on our way home from Glasgow this morning( in front door at 03.30). It had taken the sting off but very glad to run up the WBS this morning. Big lounge where WBS lives is really nice now, over 20 degs and heat shove into rest of house ongoing. WBS storage bricks are up to temp and will keep emitting long into the night while we get the fabric back up to habited space.




It's pulled duty as kettle and also tumbledryer today for that no grid bonus it provides in these solar tightening months.

Still no heating at all here, this is the temperature in our hall as of a few minutes ago:

It's still relatively mild outside, too, although getting cooler. It's 11.4°C outside at the moment, but the sky's clear and I think we'll be in for a cooler night tonight.

Joeboy wrote: ↑Thu Nov 03, 2022 4:20 pm House had crept down to 10 degs in.last few days so had a fair heatsoak to do. Ran most of the SH's while we were on our way home from Glasgow this morning( in front door at 03.30). It had taken the sting off but very glad to run up the WBS this morning. Big lounge where WBS lives is really nice now, over 20 degs and heat shove into rest of house ongoing. WBS storage bricks are up to temp and will keep emitting long into the night while we get the fabric back up to habited space.




It's pulled duty as kettle and also tumbledryer today for that no grid bonus it provides in these solar tightening months.

You'll be needing that extra heat into the house tonight seeing it's down to 3C already.

Fintray wrote: ↑Thu Nov 03, 2022 6:49 pm

Joeboy wrote: ↑Thu Nov 03, 2022 4:20 pm House had crept down to 10 degs in.last few days so had a fair heatsoak to do. Ran most of the SH's while we were on our way home from Glasgow this morning( in front door at 03.30). It had taken the sting off but very glad to run up the WBS this morning. Big lounge where WBS lives is really nice now, over 20 degs and heat shove into rest of house ongoing. WBS storage bricks are up to temp and will keep emitting long into the night while we get the fabric back up to habited space.




It's pulled duty as kettle and also tumbledryer today for that no grid bonus it provides in these solar tightening months.

You'll be needing that extra heat into the house tonight seeing it's down to 3C already.

I'm in my bed! Time difference and battery install caught up. 3C where's my 30C went?

Feck!

Joeboy wrote: ↑Fri Nov 04, 2022 7:38 am Feck!

Better get used to it!

Fintray wrote: ↑Fri Nov 04, 2022 10:30 am

Joeboy wrote: ↑Fri Nov 04, 2022 7:38 am Feck!

Better get used to it!

Trying!

Temperature in the house dipped down to 21.5°C last night, almost low enough for the heating to come on for the first time. However, today is bright and sunny, so we're getting a fair bit of solar gain, which I hope will delay the heating needing to come on for another day or two. Can't be far off the time when we need to run the heating overnight every now and again, though.