Thursday, July 10, 2008

The other side of the coin: mini-splits

Just returned from a trip to Eastern Europe.

Just as forced air HVAC systems are the king in the US, mini-splits and multi-splits rule over there. Of course, it is dictated by the environment - they are mostly being slapped on the walls of existing high rise buildings, where the choices are extremely limited - either mini-splits, or window shakers which are noisy and obstruct sunlight, or indoor portable units, which occupy a lot of already limited space.

I watched one of those being installed. Well, guess what, it is just as bad as it is here - the condenser turned out to be installed noticeably askew when we momentarily lost our vigilance, installers were visibly taken back by questions about how exactly they were charging the unit and eventually cut us off with "It's already been charged by the manufacturer", unfazed by questions about the relations between tubing length and operating pressures... Oh well, let's just hope that the HVAC manufacturer did their best and came up with some incredibly smart way to take that into account.

On the down side: God! They are sure an eyesore. Condenser is more or less OK since it is outside, but the air handler is HUGE.

On the up side: they seem to be orders of magnitude more efficient than big iron HVACs of US are. And, they're virtually silent, especially the condenser (it must be said, though, that I was witnessing the high end inverter system, cheaper models may not be as quiet).

Bottomline: if one of my HVACs decides to go south, I'll be replacing it with several mini-splits or multi-splits.

Even though they are said to be expensive, I'm sure that with my overinflated demand for quality I'll get just about the same price as I would get for a single forced air HVAC of similar capacity, plus advanced ability to place the unit where I want, not where the ducts go, plus advanced scheduling and shutoff capabilities, plus zoning out of the box, plus truckload of free space in the walls where the ducts used to be.

/me off investigating...


  1. I'm googling as I write this, but do you have any links to a quick summary of what in the world a mini/multi split is and why one would consider such a thing?

    If I find anything interesting in my Googling, I'll post it here. My usual resource for dear-dummy questions, Wikipedia, comes up blank.

    Tim Massey

  2. Something like this?

    FWICT, it's kind of like a heat pump / central air system but instead of a single large coil built into a forced-air unit, it has multiple small coils, one for each room.

    I get the zone benefits, but how in the world is this supposed to be more efficient? The expensive part to run is the compressor. How is running a compressor large enough to cool the entire house just to cool a room or two less expensive? (This is not a snarky question: I'd like to know).

    I continue to Google... :)

    Tim Massey

  3. Efficiency comes from the fact that the refrigerant line run is much shorter than in the case of the big split, and the fact that there's no duct to dissipate heat and leak air in and overcome resistance of.

    This specific unit I was talking about (Panasonic CU - E9HKD, doesn't seem to be available in the US) gains additional efficiency because it is an "inverter" (in other words, variable capacity unit). I'm yet to see true variable capacity big splits here (there used to be Trane XV series, but it apparently never gained traction because it was "too expensive" and "nightmare to maintain").