I am currently planning the air conditioning for my major renovation.
The rooms to be cooled are:
Bedroom about 15m² (160 ft²)
Office about 15m² (160 ft²)
Living room about 35m² (375 ft²) *
*also heated on very cold days in addition to the heat pump
I have chosen Bosch units for the air conditioning system.
I see two options to implement this:
Option 1:
One multisplit outdoor unit and three indoor units
Outdoor unit: CL5000M 79/3 E [7.9kW]
2x Indoor unit: CL3000iU W 20 E [2.0kW]
1x Indoor unit: CL3000iU W 35 E [3.5kW]
Price approx. 2116€
[second column]
The 7.9kW outdoor unit has a minimum cooling capacity of 3.03kW
This means that if only one of the 2.0kW indoor units runs at full power, the outdoor unit already starts short cycling (which causes higher electricity consumption and wear).
Therefore, I am considering...
Option 2:
One multisplit outdoor unit with two indoor units for the office and bedroom
Plus one single-split outdoor unit with an indoor unit for the living room
Outdoor unit (1): CL5000M 53/2 E [5.3kW]
2x Indoor unit: CL3000iU W 20 E [2.0kW]
Outdoor unit (2) / Indoor unit: CL3000i-Set 35 WE [3.5kW]
Price approx. 2376€
[first column]
The multisplit combination here has a minimum cooling capacity of only 1.7kW
As for the piping route (refrigerant lines), it basically doesn’t matter whether I install one or two outdoor units on the flat roof of the extension.
The price difference is also similar (option 2 is 260€ more expensive).
Which option would you choose?
(I have a 15kWp photovoltaic system facing west/east; still, it makes sense not to consume more electricity than necessary, and equipment lifespan is also an important factor.)
The rooms to be cooled are:
Bedroom about 15m² (160 ft²)
Office about 15m² (160 ft²)
Living room about 35m² (375 ft²) *
*also heated on very cold days in addition to the heat pump
I have chosen Bosch units for the air conditioning system.
I see two options to implement this:
Option 1:
One multisplit outdoor unit and three indoor units
Outdoor unit: CL5000M 79/3 E [7.9kW]
2x Indoor unit: CL3000iU W 20 E [2.0kW]
1x Indoor unit: CL3000iU W 35 E [3.5kW]
Price approx. 2116€
[second column]
The 7.9kW outdoor unit has a minimum cooling capacity of 3.03kW
This means that if only one of the 2.0kW indoor units runs at full power, the outdoor unit already starts short cycling (which causes higher electricity consumption and wear).
Therefore, I am considering...
Option 2:
One multisplit outdoor unit with two indoor units for the office and bedroom
Plus one single-split outdoor unit with an indoor unit for the living room
Outdoor unit (1): CL5000M 53/2 E [5.3kW]
2x Indoor unit: CL3000iU W 20 E [2.0kW]
Outdoor unit (2) / Indoor unit: CL3000i-Set 35 WE [3.5kW]
Price approx. 2376€
[first column]
The multisplit combination here has a minimum cooling capacity of only 1.7kW
As for the piping route (refrigerant lines), it basically doesn’t matter whether I install one or two outdoor units on the flat roof of the extension.
The price difference is also similar (option 2 is 260€ more expensive).
Which option would you choose?
(I have a 15kWp photovoltaic system facing west/east; still, it makes sense not to consume more electricity than necessary, and equipment lifespan is also an important factor.)
Get advice from a professional. You are often not allowed to fill it yourself anyway... Depending on the setup, you might also need a changeover box, etc. Line lengths and height differences also matter. Single split systems are often more practical. That’s what I would choose here as well. They are probably all single-phase, with one phase per unit. I would recommend looking more at Asian brands (Mitsubishi, Daikin). Pre-filled systems are now also prohibited.
For what reason would you fully recommend a single split system here?
Where is it stated that pre-charged units are no longer allowed?
Daikin and Mitsubishi are significantly more expensive, especially for the two months per year they are in use...
What do you mean by "switching box"?
Usually, the indoor units are connected directly to the terminals of the multi-split outdoor unit.
Where is it stated that pre-charged units are no longer allowed?
Daikin and Mitsubishi are significantly more expensive, especially for the two months per year they are in use...
What do you mean by "switching box"?
Usually, the indoor units are connected directly to the terminals of the multi-split outdoor unit.
Prefilled units may only be connected by certified professional companies. Therefore, they are basically not allowed for private individuals. You need a certified company to fill the system. However, the specialist company will likely refuse if you did not purchase the materials from them.
Whether to use a single-split or multi-split system depends on the specific situation. A "switching box" may be necessary to balance pressure differences. Whether everything connects directly to the outdoor unit or if, for example, two units share one line depends on the conditions on site.
I would recommend finding a professional company and discussing the project with them. Sure, it might be somewhat more expensive, but then it will work properly. Bosch is not really a major player in air conditioning systems. I’m not even sure if they manufacture them themselves. If it needs to be affordable, there are many other Asian manufacturers. But even in this case, I would consult your professional installer. They can offer more affordable options as well. They might even agree to have you do certain tasks yourself, like drilling, to save some money.
If you are worried about short cycling, you could simply choose a larger third unit. While technically the capacity may not be sufficient to fully supply all indoor units, the system will not short cycle as long as you run it at full capacity. In reality, these systems often operate under partial load, so short cycling will still be an issue. Single-split systems have smaller outdoor units that modulate down further and shorter line lengths. Usually, this is not significantly more expensive when you also consider the lines and other components.
Whether to use a single-split or multi-split system depends on the specific situation. A "switching box" may be necessary to balance pressure differences. Whether everything connects directly to the outdoor unit or if, for example, two units share one line depends on the conditions on site.
I would recommend finding a professional company and discussing the project with them. Sure, it might be somewhat more expensive, but then it will work properly. Bosch is not really a major player in air conditioning systems. I’m not even sure if they manufacture them themselves. If it needs to be affordable, there are many other Asian manufacturers. But even in this case, I would consult your professional installer. They can offer more affordable options as well. They might even agree to have you do certain tasks yourself, like drilling, to save some money.
If you are worried about short cycling, you could simply choose a larger third unit. While technically the capacity may not be sufficient to fully supply all indoor units, the system will not short cycle as long as you run it at full capacity. In reality, these systems often operate under partial load, so short cycling will still be an issue. Single-split systems have smaller outdoor units that modulate down further and shorter line lengths. Usually, this is not significantly more expensive when you also consider the lines and other components.
I am aware of the issues with the specialist company and I already have someone for that. However, they only handle the commissioning.
It costs about €500, which is what three separate units would cost me compared to a triple multi-split system.
The question is how long they would need to run before the cost is recovered (especially with the photovoltaic system).
Unfortunately, the smaller Bosch outdoor unit only has connections for two indoor units, so it’s not an option.
In terms of wiring, I don’t save much either, since the location on the roof is actually ideal for all three indoor units, and I don’t want to mount the outdoor units unattractively on the facade.
It costs about €500, which is what three separate units would cost me compared to a triple multi-split system.
The question is how long they would need to run before the cost is recovered (especially with the photovoltaic system).
Unfortunately, the smaller Bosch outdoor unit only has connections for two indoor units, so it’s not an option.
In terms of wiring, I don’t save much either, since the location on the roof is actually ideal for all three indoor units, and I don’t want to mount the outdoor units unattractively on the facade.
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