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by mc32 8 hours ago
If I don't have $30K to $50K to invest in an HVAC for the home, the next best is a relatively efficient Window unit that costs low hundreds and will help me stay alive in the heat. However enticing the price of a single duct portable unit is, do not buy it. It's a complete waste. If you go portable, go with the dual ducted one --but it's still not as good as a Window unit (which I would hope is obviously less efficient than a properly specced HVAC unit.
3 comments

> It's a complete waste.

That's completely false. They work just fine despite not being terribly efficient at least provided you install them correctly (but that caveat naturally applies to any window unit).

In fact despite the low efficiency using only one in a single room is likely far cheaper than cooling the entire house. It's the same principle as an electric space heater versus a whole home heat pump.

Of course running a minisplit only in the one room would be substantially better but for a 1 kW unit the difference is less than $1 per day (unless you're subject to the California electric grid I guess).

They work ok in some places where have insulated windows and some source of colder air to get in.

Since these one tube systems just push hot air out, you are creating low pressure in your room and you will suck the air in from somewhere. Often times simply from outside from the leaky windows.

I don't understand why it's hard to buy systems with two hoses that would keep the pressure in the room.

Insulated windows? That would apply equally to any other system. Where care is required is sealing around whatever passes through the window.

As to the negative pressure, personally I just leave the door to the room cracked open very slightly. But if you have central heat ducts air will get sucked in through that no problem.

What i mean is that if you don’t have somewhere to take the colder air to take from you just end up sucking hot air in.

In system where the pressure would be equalized the leaks would be much smaller. For some reason it's impossible to buy these type units in EU.

You can do a perfectly good, very efficient mini split for USD $5k. Avoids the leaks of window of portable units. And if you're feeling fancy you can get it as a cold climate heat pump. They're great options for retrofitting - can do multiple indoor air handlers, etc., for far less than $50k
I’m extremely happy with my single duct unit for cooling my bedroom in Berlin for the 3-6 weeks a year it is required.