Hello, I'm looking at a 24 000 btu mini split. I'm wondering if I should go with one dual zone 24000btu system or two single zone 12 000 btu unit? -i need 2 zone since it's a two story house -The price seems about the same -I like the fact that with two single zone unit, if one of them as a problem, I can still use the other one with repairing the first. thanks for your advice Alexis

Posted By Alexis on 05 Jul 2013 03:07 PM
Hello, I'm looking at a 24 000 btu mini split. I'm wondering if I should go with one dual zone 24000btu system or two single zone 12 000 btu unit? -i need 2 zone since it's a two story house -The price seems about the same -I like the fact that with two single zone unit, if one of them as a problem, I can still use the other one with repairing the first. thanks for your advice Alexis

Alexis,
I recommend the 2 separate systems (which are usually less money) for the very reason you stated , I had a dual zone fujitsu for my 2 story office that was always problematic, it only lasted about 3 years and I replaced it with separate Ramsond heat pump system

The down side to two units is additional electrical infrastructure and maintenence (2 condensers instead of one). That said multi headed units are not new but they are certainly newer than single headed splits which means less experience in the field for the installer and manufacturer both suggesting more opportunity for problems like Chris had.

In cold/very cold climates having two compressors instead of one adds significantly to standby losses since they use resistance heat at low outdoor temps to avoid excessive wear when starting up cold. The efficiency of single-head units tends to be measurably better than dual-head systems, and that may be enough to mean lower overall power use despite higher standby losses. Sizing them correctly (as always) is key to getting the best efficiency & comfort out of them, whether it's a dual-head, or two separate units.

Here in Minneapolis we install both. I have a single in my own home and will replace it with a dual head this fall. I did the loads and thought I might get by with one. Don't ask me why I thought that.

Zoning is all about comfort.

We us Mitsubishi. If you get a budget appliance, expect to work on it more often.

Though the mult-head units are "measurably less efficient. The measure is small, especially in temperate climates or in my case, where the mini goes off when the weather drops below freezing and the radiant floors come on. d

Now all I need is a heat a co-gen.