ᐅ Experiences with air conditioning in new builds?

Hello everyone,

I built a new house 4 years ago and have the problem that the bedroom on the upper floor gets very warm in summer (when there are several warm/hot days in a row).

Therefore, I am looking for a suitable split air conditioning system.

The bedroom is about 18m² (195 sq ft) in size, which corresponds to roughly 50 m³ (1,765 cu ft) of room volume.

It would be desirable to control the system with my smartphone (plus scheduling). Ideally, there would also be an option to connect it to ioBroker. I have an HVAC technician available who can install the system.

I have the following questions:

- I have a mechanical ventilation system installed. How does this work in combination with a split air conditioner? Is there anything I should consider regarding this? The bedroom has two vents (1 supply air and 1 exhaust air).

- Next door is a child’s room (about 20m² (215 sq ft) -> about 55 m³ (1,940 cu ft) of room volume). Does it make sense to switch to a multi-split system so that I can possibly cool both rooms with one outdoor unit? I do not currently need cooling in that room, but we might decide to add it in 1-2 years. Or would it be just as good to buy a separate single split unit for that later?

- Should the distance between indoor and outdoor units be kept as short as possible? For example, I wonder if the outdoor unit should be mounted directly at the gable at the top, or if I can also mount it down near the ground (there is a garden there, so the unit would be somewhat hidden [IMG alt=" 🙂"]https://www.kaelte-treffpunkt.de/images/smilies/icon_smile.gif[/IMG]

- Main question: Which air conditioner would you recommend for my needs/requirements? I am mostly looking for the best price/performance options.

- I’m happy to buy online — I read that air conditioners are significantly cheaper in Italy. Has anyone had experience with this? What about warranty, guarantee, and customs fees?

I hope to clarify some of these questions here [IMG alt=" 🙂"]https://www.kaelte-treffpunkt.de/images/smilies/icon_smile.gif[/IMG]

Best regards,
Markus

1: You don’t need to consider anything special regarding the ventilation system.
2: Two single-split units are cheaper, more efficient, and provide redundancy compared to one multi-split. The only downside is having two outdoor units.
3: No. Often, a minimum distance of 3 meters (10 feet) is required. 10 meters (33 feet) is not a problem. Beyond that, refrigerant may need to be topped up, but that’s usually not an issue.
4: The usual suspects: Mitsubishi, Daikin, Panasonic... Choose their weakest models (2-2.5 kW). Check the datasheets to see which ones meet your remote control requirements. They are all suitable.
5: Yes, Italy works well. There are no customs duties. Warranty is only provided by the manufacturer. The problem is you need to find someone with a refrigeration certification to install it for you.

Alternative suggestion: Is there maybe a central spot, preferably as high as possible, where you can install an indoor unit? If you do that and switch the unit on BEFORE it gets too warm, keep the doors open, and just let the unit run, you will have a comfortable temperature in all rooms, and the unit can really deliver its full power into the house. A 20 sqm (215 sq ft) newly built room is simply too small for almost any unit.

In general: runtime, runtime, runtime. Quickly cooling down before bedtime and then turning it off won’t work.

I find that interesting... I would also like to have air conditioning. But having the unit above the door like in a hotel wouldn’t work because the door is set too far inside... and hanging it next to or above the bed isn’t nice either...
That’s why your suggestion really piques my curiosity...
So, hang it in the hallway?

I’m a bit surprised you don’t have one yet, considering your nickname! ;-)

So: It always depends a bit on your expectations. If you absolutely cannot sleep comfortably in a bedroom warmer than 18°C (64°F), then this probably isn’t for you.

The “one device in the hallway/living room” method is more for people who just want to make the apartment or floor feel more comfortable overall and to smooth out extreme temperature spikes.

Why this works:
The most important function of an air conditioner in our climate is dehumidifying. And that works quite well across an entire floor. Sleeping at 27°C (81°F) with 70% humidity isn’t very comfortable. But 27°C (81°F) with 45% humidity is a completely different story. And if the air conditioner also manages to bring those 27°C (81°F) down to 25°C (77°F), then at least for me, the night is saved.

And that’s exactly what a single unit (especially in a new build) can do very well.

There are factors that can improve its effectiveness: If you have a very high area, like a stairwell that is open all the way to the roof, it makes sense to install the indoor unit there. All the warm air naturally rises there, gets cooled, falls back down, and spreads out.
But if the unit blows air directly toward the stairs, all the cooled air might stay on the ground floor, and the bedrooms upstairs won’t benefit. So you really have to think a bit about where to place that one unit. And of course, there are cases where the layout just doesn’t work well for this solution...

I’ve mentioned it before, but I like to say it again: This approach relies on not letting it get too warm in the first place. You need to be comfortable running the unit when necessary. If the indoor temperature rises above 24°C (75°F), turn it on and switch it off again in the evening. If it’s still 20°C (68°F) outside at night, run it 24 hours a day.
This might sound intense, but in the end, it doesn’t actually cost that much. I have a 140 m² (1,500 sq ft) older home (one floor), and in record heat years I cool it with around 500 kWh of electricity. My parents, in a 135 m² (1,450 sq ft) new build, use 300 kWh.

Snowy36 schrieb:

I find this interesting... I would also like to have air conditioning. But having the unit above the door like in hotels wouldn’t work because the door is set too far inside... and hanging it next to or above the bed isn’t nice either...
That’s why your suggestion makes me very curious...
So you mean hanging it in the hallway?

Just a quick note, these units are called inverter ducted units, and their dimensions are huge. We had a quote for a Toshiba inverter ducted unit,
Dimensions of the unit: width/depth/height 700 / 750 / 275 mm (28 / 30 / 11 inches) for our bedroom. Cost was over 5,000 EUR per unit plus small parts and installation. It was too bulky for us, especially since you also need to provide an access panel for maintenance.

Yeah, or you just use a standard split system...