Air-water heat pump - Monoblock or split unit? SCOP / COP

Hi,

we are about to commission the shell construction. The topic of the air-water heat pump is still an issue where we are not making progress. Availability aside.

Initially, a split unit from the company Ochsner was planned, with the outdoor unit planned on the garage roof. The lines would run exclusively inside the house to the basement and are within Ochsner's specification with a length of about 13m, including 6m height difference. (The garage roof was chosen because there is enough space for the outdoor unit and it is far enough away from all neighbors regarding noise.)

Our plumber and heating engineer offered a Kermi x-change dynamic heat pump 8 AW E in his offer. The installation is now oriented towards the neighbor. The description says it is supposed to be very quiet in whisper mode. I can imagine that if they mention the whisper mode, it means it gets loud when running in normal mode – that is when it is efficient.

What does the Kermi look like in reality? I couldn’t find any pictures on Google, only PR pictures from the marketing department. I have already seen a few Ochsner units.

I was told that the SCOP value is more meaningful than the COP value, which only indicates the value under optimal conditions. I once found a website where you could display many heat pumps in a table showing the (S)COP values, unfortunately I can’t find it anymore.

What is your question? Just the appearance of the heat pump?

You can find whisper mode everywhere with HPs. Then the power is limited and the device is even quieter. It can always be used when full power is not required.

The questions are:

[*]Which types of construction are more efficient, monoblock or split units?
[*]Appearance in terms of how the things look when installed, real pictures of installation sites. On the internet I only find 3D-rendered images of how they could look.
[*]Whisper mode, is that just marketing or are they really consistently quiet? To me it reads like the neighbor might hear the operation on the balcony/ in the bedroom in the evening and might complain—and during that time it runs quieter but performs its service poorly. So conversely, in normal mode, where the thing is supposed to heat my house and provide hot water, it runs so loudly that it then needs whisper mode to soothe the neighbor? I know the Ochsner split, you can hear ants fart and it works at maximum.
[*]I once found a site where heat pumps are listed and you could compare the devices. This site also shows (S)COP values. Maybe someone knows it.

Which types are more efficient, monoblock or split units

Basically it doesn’t matter. No differences that you would notice.

Appearance in terms of how the things look installed, real pictures of installation locations. On the internet I only find 3D rendered pictures of how they could look.

Go to new housing developments in your area and have a look around. The majority have heat pumps installed. Shoeboxes of all kinds in front of the doors. It’s roughly like wanting to compare the design of cell phones – they all practically look the same.

The Kermi is already quite a massive block...

Whisper mode, is that just marketing or are they really consistently quiet. To me it reads like the neighbor in the evening on the balcony/in the bedroom would hear the operation and might complain – and during that time it runs quieter, but then just does its job poorly. So in reverse, in normal mode, where the thing is supposed to heat my house and provide me with hot water, the thing rumbles so loudly that it then needs the whisper mode to appease the neighbor? I know the Ochsner split, you can hear ants fart and it runs at maximum.

Whisper mode is not marketing. Like a car engine being louder at 6,000 rpm than at idle. For example, I have never turned on whisper mode on mine (Panasonic monoblock) because the heat pump is quiet enough already. The tenant above me has the heat pump installed right under the bedroom window – it is only audible under full load with slight rustling (at night, window tilted open). Last winter she didn’t even have to run it at full capacity, that only happens at double-digit subzero temperatures.
So whisper mode can be used 90% of the time. Much more important, however, is the correct installation location and the decoupling of the heat pump. Many problems arise when mounting on wall brackets.

I once found a website where heat pumps are listed and you could compare the devices. (S)COP values were shown there too. Maybe someone knows it.

Those are all just paper data. I wouldn’t even look at them. Like a car’s fuel consumption – merely a guideline, but does not reflect reality.
Go to the heat pump consumption database, where real users with real houses list their actual consumptions. I find that better.

Thank you, very insightful!

The heat pump consumption database looks interesting. I immediately found someone nearby who is using the Kermi and has shared their data so far.

Which types of construction are more efficient, monoblock or split units

If you care about the efficiency of your heat pump, make sure to do a good overall planning. Before choosing the heat pump, the design of your underfloor heating comes first. Since many heating installers still like to do the usual standard work, it is advisable to educate yourself a bit on the subject.