Mini split heat pump
Does anyone know the difference between the Mitsubishi SVZ-KP12 and the MVZ-A12AA7? Three of the latter (MVZ) were specified to be paired with my outdoor MXZ-3c3oNAHZ2-U1 pump but the HVAC contractor installed three SVZs instead.
Thanks again and again
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I don't have any experience with these minisplits, but I'm sure some GBA users do. Giving your post a bump to the top of the forum before it gets buried.
Consider yourself lucky!
The SVZ air handlers are modulating (and usually more expensive) with at least a 3:1 modulation range (with some compressors) whereas the MVZ air handlers are not, which is why they can even be married to a single zone compressor.
With enough multi-split compressor the SVZ has a bit more peak output capacity than the MVZ too:
Since you have three 1-ton air handlers hanging on the 2.5-ton MXZ-3C30 compressor the modulation is going to matter- the MVZ would have been doing a lot of on/off cycling of the whereas the SVZs can be set up for MXZ-3C30 compressor to modulate with load a bit rather than hammer on/off in bigger steps. This is good for both as-used efficiency & comfort.
The minimum modulated output @ +47F of the compressor is 7200 BTU/hr :
7200 BTU/hr is about half the output of an MVZ, which guarantees the compressor will be cycling on/off cycling when just one zone is calling for heat under light load, whereas the SVZ can throttle back to at least 4700 BTU/hr @ 47F, and can easily handle operating at the compressor's minimum 7200 BTU/hr without cycling when the zone's load is only 7200 BTU/hr.
Dana, are you saying that the SVZ modulates even when matched with a multi-split compressor, as opposed to being matched with a single-split compressor (the SUZ)?
I thought in the past you had said you do not think Mitsubishi's IDUs modulate when matched with their multi-split MXZ-C ODUs?
Would the SVZ have lower heating capacity at low temps that the MVZ? Or does hyperheat depend solely on the ODU?
>"I thought in the past you had said you do not think Mitsubishi's IDUs modulate when matched with their multi-split MXZ-C ODUs?"
I've been informed that it's a matter of degree.
The modulation of indoor units isn't as wide a turn down ratio as when married to a dedicated compressor, and sometimes under low load conditions they run at a higher modulation level than needed for the load just to avoid cycling the compressor. But the indoor units DO modulate at least some, the amount sometimes constrained by the net load placed on the outdoor unit. The minimum modulated output of the outdoor unit is pretty much the maximum output of a half-ton head, but if a 1-ton head is the only zone calling for heat the head can modulate down to that output level.
>"Would the SVZ have lower heating capacity at low temps that the MVZ? Or does hyperheat depend solely on the ODU?"
The nominal capacity of the SVZ-KP12is higher than the MVZ-KP12, but at any outdoor temperature can only deliver that much when there is enough compressor capacity behind it. Installing an SVZ instead of an MVZ doesn't increase the capacity of the compressor, but the SVZ is capable of delivering about 10-11% more heat at max speed than the MVZ. What that means for a particular zone depends on both the capacity of the compressor, and the magnitudes of the instantaneous loads that the other zones are supporting.
"Hyper Heating" is a function of the compressor design (in the outdoor unit), not the indoor unit. Modulation is a function of both the indoor and outdoor units.
A huge THANK YOU for all that incredibly helpful information.
My system was also initially quoted for MVZ but an SVZ was installed.
The MVZ is also almost a foot taller. Based on Dana analysis of the the SVZ vs MVZ I wonder if there are any scenario where a MVZ would be better?
What size, if any, Merv filter/cabinet was added to your SVZ? Mine is a 16x20 (chosen I believe because it is the exact same size as the SVZ unit) and provides the bare minimum square footage to prevent static pressure drop. I think should increase size.
Looking for knowledgeable HVAC installer in my area to help. Does anyone on this thread work near 06830?
Mine just has the factory filter.