Air Handlers vs. Multisplit vs. Multiple Singlesplit for Cooling
Hi, I’ve been battling with HVAC design and I’m wondering a few things, Colorado zone 5. Used to be mostly heating but for the last few years, summer are hotter, and need AC for longer, and cold snaps are colder. Lots of southern windows with a 4′, 3-12 eve.
1. Are there any heatpump airhandlers that are close to the efficiency of wall mount minisplits? And if not, why? isn’t it just a single split with a big fan? Is the fan wasting all the energy?
2. How do 1-1 airhandler HPs compare to multisplits in terms of efficiency?
3. Do I continue to lose efficiency the more heads I add to a multisplit? I.e. 2 head HP is worse than single split, 3 heads are even worse than 2 heads etc.
4. Are multisplits still significantly less efficient than single splits? By such a wide margin that I should always go single split?
Another interesting thing is, with all the rebates being per system, it sounds like multple single splits could be cheaper than a multisplit. Or at least comparable. Need to investigate more. Anyone else find this to be true?
6. If the compressors will be under a (waterproof) deck, would noise be significantly more for multiple single splits vs a single multisplit? Would it be so loud that I’d want to turn it off while I’m hanging out on the deck?
I’ve asked about the HVAC design for my house on here before, and the conclusion was to use airhandlers and slim duct units, hence my question, and wondering if technology/efficiency has improved since then!
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Replies
1. Air handlers are definitely close enough to the efficiency of a ductless head that it’s probably a waste of time thinking too hard about it. SEER 26+ can be found in a central air handler.
2. One to one systems are still more efficient as far as I know and if you’re going with an air handler, that might be all you need anyway. Or perhaps 2, depends on the house.
3. “It depends” in theory, but in practice, yes more heads always seems to be the worst solution. If you had a house where every room had a 6,000 Btu heat loss, sure. That’s not reality though- the nth ductless head is going to be stuck on a wall somewhere it should not be.
4. The crappiest heat pump you could find likely trounces the nicest furnace you could buy in efficiency (including the grid losses, generation, etc).
At one point Carrier had a 1.5 ton Infinity mini split with an advertised SEER of 42, but looking online now it looks like it is no longer available. I always wondered how they got it so high, guess it must have been too good to be true. If that option no longer exists then yes, it seems a good central VRF system can compete with mini splits.