Can’t decide between two mini-split models!
Hi all –
The HVAC goes in this week, and I’m excited! This is a converted garage that will be used as a video studio, so it’s not a living space but needs to be comfortable when needed. It would rarely be used in the middle of the night, but it could happen. The garage has been air sealed and insulated and I’ve had a manual J which said I need:
20,503 BtuH of heating
7756 BtuH of cooling
The installer recommended an 18RLB Fujitsu model, which sounds good. However, I learned that at our elevation (5280) Fujitsu said I should remove 17% of the output. That makes me wonder if I should consider a ‘high heat’ model by Fujitsu.
The 18RLB does:
nominal cooling 18k
min/max cooling 3100 – 19,000
nominal heating: 18k
min/max heating: 7,000 – 20,000
If I consider the 17% reduction due to altitude, it seems to me that this unit might struggle a bit on those coldest days. Reading the Fujitsu site, I saw the 15RLS3H which offers:
nominal cooling 14.5k
min/max cooling 3100 – 18,400
nominal heating: 18k
min/max heating: 7,000 – 23,900
The 15k unit is a bit more expensive, but also has a higher HSPF, SEER, and EER. It’s very slightly higher on HI (45/45 vs. 42/43) but nominally quieter on quiet mode (26/27 vs 26/27).
If I am understanding correctly, after the altitude correction the 15k unit would be 19,991 which is just a bit lower than what the manual J indicates but very close, but it would also be a bit more efficient. The 18k unit is a bit cheaper, but after altitude correction it’s not even close to the required heating output.
Meanwhile there is an 18k high-heat unit that does 7000-23,000 of cooling and 7,000 to 29,000 of cooling, and 7,000 to 29,000 of heating. This seems a bit overpowered on both cooling and heating so it seems a poor fit.
This is like a puzzle – trying to find the right size! I really don’t need the unit to be able to run well at -15 below, which is evidently the big draw of the high heat models. It’s rare we even get below 5 degrees here. But, the 15k high heat unit seems like it might be the overall best unit.
How to decide? thank you! – Dave
P.S.- I do understand that the manual J is never 100% accurate, and there are tons of factors. But, still I hope to make the best decision even taking that ambiguity into consideration.
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