Minisplit sensible heat ratio (SHR): Mitsubishi FH09NA high 0.92 SHR for real?
I live in Southern Ontario Canada, in an older bungalow with terrible ductwork. I have a older natural gas furnace, a boiler/panel rads, and a wood stove in the house but no AC. Since my furnce is older I’m think of installing a mini split or 2 where I don’t currently have radiators. That will make me less reliant on an old furnace, and get me some efficient air conditioning. And allow me to ditch the bad ductwork.
I’m looking at installing a Mitsubishi FH09NA mini split heat pump to serve my Kitchen and Living Room area. The heat loss calc for the areas comes to 9700btu/hr.
I noticed the FH09NA has a SHR in the mid 0.92 (0.6pints/hr). The FH12NA has a sensible heat ratio of 0.83 (1.9pints/hr). The min capacity in cooling is within 700btu for the 2 units (FH09-1700btu/hr FH12-2500btu/hr) so I’m thinking of going with the FH12NA for it’s better latent capacity even though it’s a bit oversized.
The FH09 does have a much lower minimum heating rate of 1600btu/hr versus 3700btu/hr. Will the SHR improve on the FH09na as it modulates down? Is the bad (high SHR) only so high because the fan is screaming on high for the submittal data test? Will the SHR be lower in the real world?
I know the FH09 is the right size for my application but I’m worried about humidity control since my house is pretty shaded. I don’t get much direct summer sun coming in windows, since my house has decent overhangs so my load is skewed a little more towards latent than is normal for my area.
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