Fujitsu 09LZAH1 vs 12LZAH1 heating performance
I’ve bought a new house recently, and am looking to install a minisplit.
The short story is: Raised ranch, in Windsor County, VT. previous owner had Efficiency Vermont come through and do extra air sealing and insulation, so it’s in very good shape energy wise.
The basement is finished, but we are only interested in the first floor. My manual J calculation put the first floor heating load at 15.5k BTUh at the 99% outdoor temp (1F), with conservative assumptions. More reasonable assumptions (detailed further below, for those curious) cut it closer to 12k-13k.
I’ve decided to go with Fujitsu (again, more details later for those interested). So our model options are 09LZAH1, 12LZAH1, 15LZAH1. Guy quoted only $250 less for 09LZAH1 vs the 15LZAH1. He was trying to sell me on the 15LZAH1. I was leaning toward 12LZAH1, figuring that with such a small cost difference I might as well meet the full load. But the contractor pointed out that the 09LZAH1 and the 12LZAH1 have basically identical heating performance. I looked it up, and it seems he is right. Fujitsu advertises their 09LZAH1 as consistently exceeding the nominal heating loads. Specifically, the 09LZAH1 allegedly is capable of ~14k BTUh at -5F and ~11k BTUh at it’s -15F limit — almost identical in performance to the 12LZAH1.
Is the difference between the two units just cooling performance? It seems very strange to me that the units would be so similar, so I was hoping someone might have some firsthand experience with them that could attest to Fujitsu’s figures, or provide a technical explanation as to why that is the case. As it stands now, I’m leaning toward 09LZAH1.
Extra details, for those interested:
The conservative assumptions I mentioned before were as follows:
-The basement garage would be at exterior temp (has R10 foam/air sealing isolating it from house)
-The south facing, partially insulated sun room would be at exterior temp.
More reasonable assumptions of those deltas shaves off ~2-3k BTUh, but unfortunately I don’t have any good real-life data to go off of.
Additionally, there is no need for me to meet the full load with the minisplit; there is electric baseboard in every room, and a propane space heater in the basement and in the living room. None will be going out of commission, so there will be plenty of capacity available in unusually cold weather.
As for why fujitsu was chosen:
Initially I had two contractors come through — one for Fujitsu, one for Mitsubishi. The Mitsubishi guy performed a manual J at a design temperature of -13F, the limit of the unit. I considered that pretty shady, and had him rerun it at 5F. He got 12k BTUh then — but for just the main living area (he didn’t measure the bedrooms at all). When I did the calculation, I got 8-9k for the same space. He would not share his calculations (or even the unit he was going to spec!) so I decided him not to be trustworthy.
Fuijitsu guy didn’t do a calculation and didn’t know what a manual J was (!), and said there was no point in doing a calculation. But his “rule of thumb” was more accurate than the guy who ran the numbers. Still oversized, of course, but at least I didn’t feel like I was being manipulated. Still, not ideal.
If anyone has additional contractor suggestions, I am open to them.
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