Do heat-pumps make less noise when less power is asked for? Daikin, Atlantic...

[Garald]

So, I now have offers from two installers - one is for an Atlantic Extensa Duo 10 RS32 heat-pump (peak power closer to 9kW than to 10kW) and one is for a Daikin Altherma 3 R W 11 kW. The two units are very similar from the point of view of their technical specifications (for instance, essentially identical SCOP; should be about 3.9 at 45 C in both cases). Both are somewhat overpowered - not my choice; installers overestimate, in part because they don't want liability. (Even the 11kW installer agreed verbally that 9kW will give me plenty of elbow room, even with an integrated water heater.) Both produce a notch more noise than I had hoped for - I was aiming for 60dB, the Atlantic produces 62dB, Daikin produces 64dB. The external unit will go in a shared courtyard - I've got written authorisation from the coop, but I want to tread carefully.

 

Question: what happens in summer, when (a) neighbors are more likely to have their windows open, (b) I won't need that much power (just DHW, and also cooling, not at the same time, obviously; cooling would be just a pittance (< 1kW), used by the PIV)?

 

- Daikin has a quiet mode (-3dB) and a night mode (-5dB), but I can't find how much heat it produces then;

- Atlantic does not have a quiet mode. If much less than full power is demanded from it, is it likely to just turn more slowly and be quieter?

 

The technical specification sheets don't seem to clear these issues (but maybe I haven't looked hard enough).

 

(Opinions on Daikin and Atlantic are also welcome. Old threads online (<2016) clearly favor Daikin; it's unclear to me what is the case now.)

[ProDave]

Mine (LG 5kW) is nosiest heating DHW then usually nearing the end as the tank water approaches it's 48 degree target and the HP is having to deliver water at 55 degrees to make any meaningful input to the tank.

 

If you are not using up surplus solar PV could you time it where possible to do the DHW heating at night when people are not likely to be outside?

 

Just heating the house it is very quiet.

[Garald]

1 minute ago, ProDave said:

If you are not using up surplus solar PV could you time it where possible to do the DHW heating at night when people are not likely to be outside?

 

People don't spend time in the courtyard as it is (though they might start to do so once I make it nicer). My concern is more what happens when it's the worst of summer and they keep their windows open - particularly when they sleep.

 

How do I find out how programmable these units are?

[Garald]

... and right, the problem is that I couldn't get the Daikin installer to offer me a Daikin 8kW, even though he agreed we had done a smashing job with the insulation, and that even at 9kW we would have much more wattage than we need. Nothing by Daikin between 8kW and 11kW.

[Garald]

If only I could get an offer for a Mitsubishi Power Inverter Silence Duo 11 200L...

[ReedRichards]

You really ought to be able to control when the unit comes on and therefore to make sure that it does not come on at night during summer.  You can certainly do that with my LG heat pump and I would not consider a unit that "does it's own thing" and cannot be controlled in this way.  If you can find a copy of the manual it should tell you how to program the timings.