Mitsubishi SVZ install with ERV hookup using the same ductwork opinions
I know this sort of thing has been covered quite a bit on here but here goes.
I’m in Zone 4, we remodeled an old 2 story house with new Zip sheathing, 3″ of exterior polyiso and 7″ of polyiso on the roof. Its an open floor plan home with cathedral ceilings so not the easiest to heat/cool with limited space for ductwork. but its well insulated/sealed now and does have a finished basement and conditioned attic. 13 KW Solar on the roof and will be installing efficient appliances to hopefully achieve net zero.
We are looking at installing a Mitsubishi SVZ in the basement. I’m considering hooking up a Panasonic ERV to the ERV input of the SVZ as we have limited space for separate ERV ductwork. Has anyone does this and can report on the results?
The other option is we could install 2 heat pump systems with the basement/1st floor on one and the attic/2nd floor on the second. Could then have an ERV in the attic with separate ducts but this option is a bit more complicated/expensive and seems more taxing on the energy usage?
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I haven't done it with that unit but used a different ducted mini split and worked very well. My preffered method is the hybrid ducted setup where only the fresh air supply is connected to the return, the stale air pickups are run to the kitchen/basement/mostly used bath. This saves a bit on bath fans and tends to be a wash for overall install cost.
The good thing is modulating heat pumps such as the SVZ run the blower 24/7 as some speed so you don't need to interlock the blower with the ERV.
One thing to watch with the IB100 unit is the control signals are line voltage with a switched neutral. This means you can't use standard house smart controls directly as those are switched hot couple of threads on how to deal with that:
https://www.greenbuildingadvisor.com/question/panasonic-intellibalance-100-install-questions
You interlock the controls with the ERV, the SVZ manual shows how to do it:
https://www.mylinkdrive.com/viewPdf?srcUrl=http://s3.amazonaws.com/enter.mehvac.com/DAMRoot/Original/10006/M_SVZ-KP-NA_Install_MD-1404-K021_V_4_2022.pdf
As for a single unit cooling a two story structure it is not an issue but you must have a large return on the 2nd floor near the ceiling. This does take up space to run down to the basement but it needs to be installed.
If this is not an option, the attic mounted unit is not an issue since you have a conditioned attic. Make sure to run the heat loss numbers on your place, with that much insulation your loads will be pretty small, you want to get the heat pump sized correctly to avoid issues with humidity removal.