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Grant Aerona R290 (15.5kW) - How is DHW Target Temp calculated?

 
Air Source Heat Pumps (ASHPs)
Last Post by TaffontheTaff 3 weeks ago
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 TaffontheTaff
(@taffonthetaff)
Active Member Member
Joined: 3 months ago
Posts: 8
Topic starter 18/05/2026 12:17 pm   [#3006]

Hello all,

We have just had a Grant Aerona R290 installed and it seems to be having a problem in getting to the target DHW temp of 47c. It has a hysteresis setting of 6c and I recently discovered that it has a DHW temp correction of 2c in the Installation Controller - Main heat source configuration. It also has a DHW Set Temp of 45c on the controller display (but 450c on Econet24!). I suspect the latter is a default value though.

I think that the real target would be 47c plus the temp correction of 2c giving 49c. However, would it be "satisfied" if it came up to the hysteresis value of 49-6? Aaarrgghh! (It was much simpler with our older GSHP.)

I reckon this results in the HP attempting to get the DHW up to temp and therefore cycling as shown on Home Assistant:

image

I do not understand why the heat pump would just stop attempting to get the temp up to target.

Makes me wonder about Econet24 too - it lost Circuit 2 last week and I thought the power cut this morning would reset the link from the Econet300 to the server. Still no circuit2!

When I reduce the target or use the schedule to remove the DHW priority, the CH system works well with an existing UFH utilising Uponor controllers.

It doesn't help that there are some discrepancies between the Smart Controller manual and what the Smart Controller is displaying. There again, this technology is advancing at a fair old pace!

Anyone had similar problems with these heat pumps or Smart Controllers?

Any advice/tips would be gratefully received as I have racked my poor befuddled brain with this!

Thank you,

Gerald.

 



   
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 TaffontheTaff
(@taffonthetaff)
Active Member Member
Joined: 3 months ago
Posts: 8
Topic starter 20/05/2026 8:01 pm  

Just in case someone else has the misfortune to come across similar issues and finds this topic...

The installers responded quickly - fair play to them - and had Grant on the phone while they were here. There was quite a bit of discussion which resulted in a curve of 1.0 for one circuit and a DHW temp correction of 5c under Installation Controller - Main heat source. The sensor was moved to another pocket as the original position would have meant incoming cold water would have influenced it quite directly. Working well now but the term hysteresis in this case does not mean a buffer above and below the target temperature, merely below - 6c in our case.



   
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