尺寸迷你分型冷却和湿度控制。
我们正在建设一个小木屋CZ 6。这是一个海sonal cabin that will see limited winter use so while we do want a mini split that will heat the space we are not concerned if it ends up being undersized. There is so much free firewood in the area that the Forest Service and private land owners often burn huge slash piles in the winter just to get rid of it. I also have access to hundreds of board feet of free hickory cut-offs from a local cabinet shop. So we’ll have a wood burning stove regardless.
As I talk to local contractors it seems some are stuck on sizing the unit for heating and thinking the cooling functions will be good enough.
我不相信任何承包商都将使用手动J方法，因此我计划自己执行此部分。我已经阅读了该主题的相关GBA文章。
客舱640平方英尺，拥有大约6900立方英尺的内部空间。我们正在提出12,000或18,000 BTU迷你分裂的建议。如果我们确实在这两种尺寸之间的围栏之间，我想在两者之间做出受过教育的选择。
We are concerned about humidity control. I know there are mini splits with a drying modes but that aside I have a question about humidity control in cooling mode.
Specifically will more humidity be removed with a slightly smaller unit that will move more air across the coils or a slightly larger unit that will ramp down and move the air more slowly across the coils?
这可能已在GBA文章中涵盖，我没有书签。与涵盖这一点的文章的链接将受到赞赏。
Replies
The maximum cooling capacity of a cold-climate 1-ton is on the order of 13.5-14,000 BTU/hr at a interior-to-exterior temperature difference of 15F (80F inside, 95F outside is the test condition). That's likely to be on the order of twice the cooling capacity required.
http://meus1.mylinkdrive.com/files/msz-fh12na~muz-fh12na_submittal.pdf.
https://portal.fujitsugeneral.com/files/catalog/files/12RLS3H6.pdf
除了运行时，除了发生除湿，所以关键方面是一个迷你拆分，具有低低的最小调制输出，使其几乎不断运行。大多数区域6个位置的外部设计温度良好在95°F以下，很多85f（在迷你分体式测试条件下井），以确保有足够的明智的载荷来保持旋转的东西，最小调制必须低于旋转尽量。大多数1.5助理的最小调制输出将超过您的峰值冷却负载的一半以上，甚至1吨可能会遇到该问题。
你应该看3/4茄奖，不是1-1.5罐。冷酷的气候3/4辅助仍然提供超过11,000 BTU / HR的冷却，您可能的峰值要求几乎肯定不到9,000 btu / hr（它是测试的标称调制率，即它测试的标称调制率）的第一层供应商你应该看一下三菱FH09NA，这会调制到富士通的9 rls3h的大约一半。富士通具有更低的低温容量，但两者都可以处理整个负荷降至+ 5F左右。
https://portal.fujitsugeneral.com/files/catalog/files/9rls3h6.pdf.
http://usa.mylinkdrive.com/uploads/documents/4560/document/MSZ-FH09NA_MUZ-FH09NA_Submittal.pdf
Most mini-split can operate in a "dehumidify" mode, which maximizes the latent to sensible load ratio, but it still has to be running to provided that dehumidification. If your cooling load at the 1% condition is, say, 6500 BTU/hr, a the Fujistu would be cycling on/off most of the time, whereas the Mitsubishi 3/4 tonner would be running almost all the time.
Have you considered a standalone dehumidifier if you are concerned about humidity? Having simple, discrete systems seems simpler than trying to do it all with one device. That way you can size the mini-split just right for your heating and cooling needs, and you can size your dehumidifier just right for your dehumidification needs, and you don't have to make any compromises trying to get the mini-split to do both.
在第6区的这个尺寸的房子在所有情况下都不有任何问题，除非舱室屋外，否则在屋檐设备或其他东西均有相同的沙线设备。关键因素是对负载和最小调制输出的右侧尺寸。在高度明智的载荷条件下，室外夏季露点仅在4区位置高，与摩根海岸（甚至是大西洋）地点不同。在区域6的情况下，通风可以可靠地处理除湿载荷是否有很多明智的冷却负荷。
Typical cooling/floor area ratios for smaller houses even in the humid southeastern states with high latent loads and high 1% outside design temps are usually on the order of a ton per 1500' or a ton per 1000'. This house is 640', and most likely has a cooling load of about a half-ton. See Allison Bailes' compiled Manual-J cooling load ratios plotted against house size (most of those houses are in zones 1A to 3A):
//m.etiketa4.com/sites/default/files/images/Bailes%20graph%20for%20Manual%20J%20blog.preview.png
The absolute worst-case house in Bailes' graph had a load ratio of a ton per ~650' which means if THIS ~650' house were a barely insulated place with a lot of west facing glass in a Louisiana swamp it might actually need a full ton of cooling. But most 3/4 ton mini-splits can actually deliver a full 1-ton of cooling when running at maximum speed, so you're not really giving up much by going with a more appropriately sized 3/4 tonner.
Most reasonably tight code-min houses will have heat loads under 15 BTU/hr per square foot of space at the 99% outside design temperature, maybe 20BTU/ft for very small houses. While there are many exceptions to prove the rule, that implies the 99% heat load of a 640' cabin will run somewhere around 10,000 BTU/hr, possibly less, but also probably not more than 13,000 BTU/hr. A cold climate 3/4 tonner will typically deliver 10,000 BTU/hr or more at 0F, and there's a wood stove to deal with anything colder, if needed. The Fujitsu's have a "Minimum Heat" mode to keep the place at 50F, and the Mitsubishi's can be be programmed to a 50F setpoint by using the "Smart Set" mode, if that's desired. (Most people would just drain the plumbing before winter and let it freeze.)
If the mini-split is going to be a cooling-only type, pull the submittal sheets on any of the proposed units, and only pick those that modulate down to 2000 BTU/hr or less. Again, lower is better, independent of the max cooling. The 1-ton Mitsubishi MSY-GL12NA-U1 & MUY-GL12NA-U1 can throttle back to 1500 BTU/hr :
http://meus1.mylinkdrive.com/files/MSY-GL12NA-U1-MUY-GL12NA-U1_ProductDataSheet.pdf
但是，这系列中的3/4吨仪只能退出3,800 BTU / HR，使其在最大的冷却视角下更加“右尺寸”，因此申请不太理想的选择：
https://www.ecomfort.com/manuals/mitsubishi-be0a6dd851d9866451b22863b20994d9.pdf
Brendan,
我们绝对考虑沿着除湿机的立场。我有那个在更长的原始帖子中撰写，但决定最好稍后和删除我的帖子的问题。我对这种情况感兴趣，如果真正对两种尺寸的阈值的阈值会更好，如果除湿性比加热更重要，那么更好的尺寸。
达娜，
As far as outside design temperatures, the cabin is in the beginning of a canyon with strong orographic lift, or so I'm told. As I understand it this contributes to warmer winters and cooler summers. Or maybe the cooler summers are due to the 4400' elevation.
Can you be at least a bit more specific about the location, to get a better handle on the latent vs. sensible load estimates? The nearest listed city in the Manual-J manual might be useful- the moisture levels won't be very far off, even if the temperature data is.
https://articles.extension.org/sites/default/files/7.%20Outdoor_Design_Conditions_508.pdf
A smaller/lower minimum modulation is the key factor, independent of the maximum capacity, as previously discussed. That pretty much rules out all 1.5 ton mini-splits, and most 1 ton minisplits. Pull the submittal sheets on the specific models of any proposals to make apples-to-apples comparisons, since the minimum & maximum modulated output are done at a standard set of conditions, and can differ quite a bit from the "nominal" capacity, which is the modulated level used for calculating seasonal efficiency.
Cooling-only, or heat pump?
Cabin is located between Hill City and Keystone, South Dakota. If the nearest weather data is from Rapid City then I'm guessing data collection point is 1200' or so lower than our cabin.
I would like the mini split to have a heat pump but am not concerned with it being able to meet all of our heating requirements. As mentioned earlier cabin will have a wood stove and the 100 square (850 cubic) foot mechanical/bathroom will have electric cove heaters.
Latent loads are low to negative in that location. Take a look at the dew point graph at the bottom of this page:
https://weatherspark.com/averages/31440/Rapid-City-South-Dakota-United-States
The mean outdoor dew point even in JULY is a bit under 55F. With 55F dew point ventilation air at a comfortable & cool 75F indoor temp becomes 50% RH, so a mini-split running in "dehumidify: mode might even OVER-dry the place. Most of the time simply bumping up the ventilation rate would be able to bring the humidity under 50%RH, and outdoor dew points over 55F only happen when it'spretty hot out, at which point the AC would take care of it, even without resorting to dehumidify-mode.