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Grant Aerona Air to Water R290 6.5 kW - Quiet Mark and Silent Running

Air Source Heat Pumps (ASHPs)

Last Post by JamesPa 3 weeks ago

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Chris66

(@chris66)

New Member Member

Joined: 6 months ago

Posts: 2

Topic starter 05/08/2026 3:10 pm [#3128]

Helping a family member with brand new installation of a Grant Aerona 6.5 kW heat pump. They, like most, just running DHW few times a day at the moment and one of the timed cycles is during off peak night time period. Unfortunately during the first 5 minutes of starting the external unit fan speed runs over 800+ rpm and the compressor working hard too. Then it drops to run at steady 400 rpm and all is quiet again.

In a quiet street and plenty of open bedroom windows as everyone tries to cool down at night, the first 5 minutes of running at the higher speed is quite noticeable even with the Grant 'Silent Mode' running. Once it drops to c 400 rpm and the compressor slows down it's fine and hardly noticeable. But annoying Silent Mode starts with 5 minutes of noticeable noise.

I can see in the Service Parameters, Heat Pump and then Heat Pump Settings it is possible to manually reduce Maximum Pump Speed from factor of 100 ( presumably the compressor) and Fan Speed from 0 to 4 by reducing rpm from preset ( with maximum of 1000 rpm).

Call to Grant Technical Support says no option to set or link Compressor / Fan speed to 'Summer' mode when just running DHW but OK to manually adjust under Service Parameters to experiment.

Anyone else with a Grant Aerona R290 been operating 'Silent Mode' over night and coming across initial ramping up at start of scheduled slot and using Service Parameters to adjust down?

Thanks in advance, Chris

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bobflux

(@bobflux)

Estimable Member Member

Joined: 6 months ago

Posts: 159

06/08/2026 10:47 am

My LG does the same: when turning it on, it's below the flow temperature setpoint, because the water cooled down. So it goes "Oh no we're too cold, let's go full power to catch up" then once it reaches the temperature setpoint, it calms down and lowers output to what's actually needed.

"Pump speed" setting is most likely the circulator speed. If you lower it, water flow will be reduced. This might help in an indirect way, because a lower flow needs lower power to reach the temperature setpoint. Perhaps then, the heat pump will be satisfied with starting at lower power (ie, less noise) instead of full.

What you'd actually need is either a "power limit" setting, or to slowly ramp up the temperature setpoint to prevent the heat pump from deciding to go full power.

👍

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Chris66

(@chris66)

New Member Member

Joined: 6 months ago

Posts: 2

Topic starter 06/08/2026 5:23 pm

@bobflux Thanks for the suggestion and we’ll give it a try to see what happens.

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JamesPa

(@jamespa)

Illustrious Member Moderator

Joined: 3 years ago

Posts: 5316

07/08/2026 2:56 pm

Thats all interesting. DHW on my Vailant seems to respect quiet mode, in fact some on openenergy monitor describe it as a 4th possible setting for DHW because it slows the ramp up.

For my money respecting quiet/silent mode unless the heat pump is otherwise going to die in a ditch (eg due to defrost failure) is the appropriate behaviour and Im a bit surprised some heat pump manufacturers dont. You live and learn

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.

👍

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