Does it make sense to retrofit an air conditioner?

Hello everyone,

We have been living in the house since December 2016, and during the planning and construction phase, I never even considered installing an air conditioning system.

Basically, we manage without one. In the extreme summer of 2018, we had a maximum of 25.5-26 degrees Celsius upstairs. That was just about okay, but for me personally, it was borderline for sleeping. And we will likely experience such summers more often in the future.
In summer 2019, it was never more than 25 degrees, but unfortunately with very high humidity at times, which made it unpleasant. Early morning ventilation didn't help much either; it only made things worse. And ventilation only works if the shutters are open, but we like to sleep in the dark...

Having since learned that air conditioning units are significantly cheaper both in purchase and power consumption than I had always thought, I guess I should have planned for one back then. Hindsight is always 20/20...

Now the idea occurs to me whether it's possible to retrofit an air conditioner, at least for minimal functionality.
The requirements would be:

[*]Cooling the air temperature upstairs by a maximum of 2-3 degrees; if we can keep it under 24 degrees, that is completely sufficient. We don't want it any colder.
[*]Dehumidifying the air.

We have a staircase with a landing and next to it a wide hallway upstairs.

The idea would be to install an indoor unit in the stairwell, above the window, directly below the upstairs ceiling. From there, the unit could blow air along the hallway, and with the doors to Child 1 / 2 and the bedroom open, at least some air would reach these rooms. Possibly supported by an oscillating fan standing in the hallway. The unit would run in the morning until shortly after noon when no one is home anyway. This way, the house would be pre-cooled during that time and wouldn't continuously heat up. As said, the goal is only to reduce the temperature by 2 degrees, not to cool all rooms evenly and draft-free down to 18 degrees.
The outdoor unit could be placed next to the ledge and then the lines routed mercilessly up the corner. Because of my setup, in one pipe. This is our north side where our trash bins and firewood are stored. So, it's not exactly the prime side...

Questions (although I am aware that this cannot be predicted exactly):

[*]Does such an arrangement make sense, or is it a crazy idea ending up with an ice-cold hallway and rooms that are just as warm as before? I have seen a similar setup somewhere here before, but I can't find the thread anymore.
[*]What cooling capacity should one expect? The bedroom, hallway, and both children’s rooms together have about 65 sqm. I have seen figures ranging between 4 and 6 kW. But we don’t want to cool down to 19 degrees, just reduce a bit.
[*]Are there devices/brands with somewhat stronger fans? We would need a unit that can blow its airflow a bit further...
[*]How is it actually with condensate water? Would you then presumably need another hose through the outer wall?

Best regards,

Andreas

I have also dealt a bit with this topic. I also spoke with a climate technician.

Your plan probably won't work like that. We were recommended a split air conditioning system with 3 indoor units (for the 3 bedrooms). Personally, I would install ceiling units connected via the storage and mount the outdoor unit on a roof console.

However, you have to keep in mind that each unit requires a condensate drain.

We have put our considerations on hold because we want to do other projects first.

Please remember that cold air falls downwards. So nicely down the stairs and the warm air from the ground floor rises up. I assume that child 1/2 will not benefit at all from the air conditioning with your planning. RFR has written something similar.

Hi,
thanks for the reply. The "correct" solution would be 3-4 indoor units, that’s clear. But I do shy away from the effort, and especially the condensate drain of the distributed indoor units will be difficult. That’s when you start with units with integrated pumps and all that stuff. I would also like to avoid having to drill through the upper floor ceiling. We have a concrete ceiling there; you can’t just make larger recesses in it.

I will probably ask local HVAC contractors soon.

Best regards,

Andreas

I really have no idea about the subject, but couldn’t the same effect be achieved with mobile devices in the bedrooms? On average, it is only needed on a few days per year. And outside of the height of summer, the devices could be stored elsewhere. Or am I imagining it too simply? Or are the mobile devices no good? Ideally, the installation would take place during the construction phase of the house, but perhaps as a straightforward retrofitting solution.

Mobile devices are not that efficient. With the better ones, you still have to pour water in regularly. They are also louder. The biggest problem is the exhaust air. Either an unattractive and inefficient option through tilted doors and windows with sealing tape... Or a wall duct. In terms of price, you are then not far from a solid solution. Monoblock devices are okay for apartments where you can’t or aren’t allowed to make changes. We ourselves used them last summer in our attic apartment.