ᐅ Is it worth preparing for air conditioning installation?

Thank you very much in advance for your answers! So far, I’ve gathered that you probably need:
- two pipes per indoor unit (one supply and one return?)
- power supply on the roof (or at the outdoor unit)
- power supply at the indoor unit
(a bus system will not be used in our case)

The condensate forms at the indoor unit (I assume), which means I need to run some kind of drain hose to a wastewater pipe, right? That alone probably wouldn’t be a problem, but possible odors from the sewage system could be, if no precautions are taken.

Regarding the refrigerant lines: where could the critical points be? It sounds like rather small metal pipes; does the pipe diameter vary between manufacturers? In principle, one would think that installing these pipes in a wooden house that is not yet finalized from a construction technology perspective shouldn’t be a huge problem— or is it?

I hadn’t considered the weight. What load can a roof typically support per square meter (per sq ft)? And what is the weight of an average outdoor unit?

The preparation usually only involves a 10cm (4 inch) thick empty conduit and a power outlet near the indoor unit. I consider 1300.-- to be too expensive for that. I wouldn’t install refrigerant lines now either, as they just get contaminated, seals become brittle, and if a new refrigerant is introduced in a few years, they might not be compatible. The condensate can be drained anywhere, onto the roof, allowed to drip down, or even into a tray that you empty yourself. With the "simple" units, you can only connect one indoor unit, so it is often cheaper to have three separate indoor/outdoor units than one outdoor and three indoor units.

Nixwill2 schrieb:

Thank you very much for your answers so far! What I have gathered is that you probably need:
- two pipes per indoor unit (one supply and one return?)
- power on the roof (or at least at the outdoor unit)
- power at the indoor unit
(a BUS system is not an option for us)

The condensate forms at the indoor unit (I assume), which means I have to run some kind of hose to a drain pipe, right? That alone probably isn’t a problem, but possible odors from the drainage system could be, if you don’t take proper precautions.

Regarding the refrigerant line: where could the main challenge be? It sounds like relatively small metal pipes; does the pipe diameter vary between manufacturers?
In principle, you would think that installing these pipes in a timber house that is not yet planned from a manufacturing perspective shouldn’t be a big problem, or is it?

I didn’t consider the weight; how much load can a roof generally carry per m² (square meter)? And how much does an average outdoor unit weigh?

- By BUS system I do not mean KNX or similar; rather that some manufacturers require an additional line as a BUS connection to the outdoor unit.
- Having power lines on the roof is useful 😉
- The indoor units usually do not require an extra power supply as they are powered from the outdoor unit.
- Just search for insulated refrigerant lines on Google (they come in coils).
- If you want to connect the condensate to the drain pipe, you need to install a trap (P-trap).
- The most common refrigerant lines are 1/4" x 3/8" and are generally sufficient for standard systems. Anyone can really do the installation, but you should make sure there is a continuous refrigerant line between indoor and outdoor units (otherwise you might have to open the wall to fix leaks if there is a solder joint there). Also, the maximum length specified by the manufacturer should not be exceeded.

Dogma schrieb:

- If you want to connect the condensate to the wastewater pipe, you need to install a trap in between.

My HVAC technician also mentioned that there must be a free-fall section for the condensate to prevent bacteria from the wastewater from entering the air conditioning system.

Nixwill2 schrieb:

- Power supply for the indoor unit

The power line for the indoor unit usually comes from the outdoor unit. You can simply run the cable through the conduit or install a cable from the outdoor unit location to the indoor unit right from the start.

Dogma schrieb:

- Indoor units generally do not need a separate power supply as they are powered by the outdoor unit

Exactly!

Grundaus schrieb:

The condensate can be drained anywhere—onto the roof, dripping down, or even into a tray that you empty yourself.

I wouldn’t do that in a new build. Water will accumulate there. I would always run or prepare a drain pipe at the indoor unit locations.

Wow, there’s really a lot going on here! I’m definitely not the only one sensitive to heat 😀.

The idea of using empty conduits actually makes sense. I just imagine it might be easier to install those two small pipes along with a power cable at the same time—you can probably fit them all in together. But that’s just a guess...

It doesn’t sound like that much extra work! Adding a wastewater pipe at this stage shouldn’t be an issue in my opinion.

I think I’ll bring it up with the home builder directly. Your posts are encouraging.

I looked up the weight of the outdoor unit—it’s below 50kg (110 lbs). Isn’t that light enough for a roof to easily support?

What I couldn’t find is the maximum length of the pipes. Does anyone here have a rough estimate? That would make it easier to figure out where else I might place the outdoor unit apart from the roof...