难看的爬行空间机械通气问题
Hello,
I am building a diy ICF house on a crawlspace (ICF from footer to roofline) in Louisville, KY Climate Zone 4A. I planned on having an unvented crawl space and have a question in regards to the energy efficiency of what I am thinking. I was hoping to save on the HVAC installation cost by installing a 36k BTU 4 zone mini split diy mini split and using supplemental gas or electric heat when it gets to cold outside for the heat pumps. The house will be roughly 1750 sq ft.
Code book reads like so on unvented crawl spaces
One of the following is provided for the under-floor space:
- 2.1连续运动机械排气ventilation每个50平方英尺的每分钟1立方英尺（0.47磅）（4.7米2) of crawl space floor area, including an air pathway to the common area (such as a duct or transfer grille), and perimeterwalls保险金Section N1102.2.11of this code.
- 2。2Conditioned air每个50平方英尺的每分钟（0.47 L / s）的速率提供大小以等于1立方英尺（4.7米2）楼层面积，包括一个return airpathway to the common area (such as a duct or transfer grille), and perimeterwalls保险金Section N1102.2.11of this code.
- 2。3Plenum在现有的结构符合Section M1601.5, if under-floor space is used as aplenum。
I was planning on option 2.1 installing a bathroom vent fan in the sealed crawlspace venting to outside and a one transfer grille in the floor to allow air flow from the living space. I see per code I would only need 35CFM (1750/50=35CFM) on this vent fan but was planning on a 50CFM unit or so. My question is this option for an unvented crawl seems kind of wasteful and would negate the effects of a air tight well insulated house if I am constantly blowing out conditioned air compared to the other two options. However If I use the other two options I will need to either buy another mini split for the crawlspace or hire an HVAC contractor to run duct work and use a normal ducted system. What do you all think is the cheapest / most energy efficient option?
最后一个问题，我在一起阅读代码书，并不是从爬行空间排出空气，但选项2.1实际上正在谈论排气扇从爬行空间拉出空气，并与转移格栅提供循环或反之亦然？
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答复
In my opinion you are not looking at what the code is trying to tell you.
爬行空间需要发泄到户外或调节，以便爬行空间或多或少与房屋的其余部分相同的临时和湿度。
2。1 You must blow the more or less conditioned air out of the crawlspace into the outdoors install vent so that air will be replaced with air from the living space. Note all of the air exhausted will be replaced with unconditioned air that will find a way to leak into the house.
2。2You install supply registers in the crawlspace and return registers to the living space.
2.3您使用爬行空间作为返回空气管道。
When people can’t bring themselves to call it a “conditioned crawlspace” and use words like encapsulated or unvented it makes me think they are looking for the free lunch of not having to spend money to condition the air in the crawlspace.
如果您不调节爬行空间中的空气，从爬行空间的墙壁不时会比爬行空间中空气的露点变冷。当发生这种情况时，墙壁会弄湿。这是一场俄罗斯轮盘赌的游戏，墙壁将足够湿足够长，以便模具生长和木材腐烂。
沃尔塔
DSH1109，
其中的一部分取决于您将与上面的生活空间从您的爬行空间分享空气的舒适度。即使是新建的爬行空间通常通常不会很干净，更有可能是潮湿或港口氡。通风到外面的优点是它有助于抵消这一点。
If you are fine with sharing air, a cheaper option that an extra mini-split or more ducting might be to just add a fan moving air from the main floor down to the crawlspace.
ICF houses tend to be pretty air tight, which means you'll need mechanical ventilation.
条件和排泄爬网空间的最简单方法是为您的HRV / ERV安装陈旧的空气拾取器。拾取器的尺寸为提供代码所需通风气流。这比试图发泄了很少使用的粉末室或浴室，更好地使用ERV陈旧空气拾取。
除了更有效比排气辊筒y, venting your crawlspace this way has the benefit of not mixing the air with the rest of the house and removing any radon.
谢谢你非常有用的回复。在我从未听说过的HRV / ERV的情况下，你为我打开了一个全新的蠕虫。我对如何继续困惑。你能告诉我所有陈旧的空气拾音器，并让分布为何吗？刚抓住爬行并还回到爬行或其他地区？我从我看起来的假设是一个HRV / ERV从房子和外部拾取空气，外面的混合/清洁它，然后在某些地区重新分配到房子。
如果这将有助于一个4间卧室，我已经包括平面图。迷你拼接将在3间卧室，不包括客房和主要起居区。
Akos，这是一个非常有趣的“开箱即用”的想法。它似乎有很多意义。当您指出时，它会解决几个问题。我希望这里的人不仅仅是解除这个想法，因为它是如此非常规，并开始考虑使用ERV的返回空气管道，帮助将爬行空间与已经有条件的房屋空气调节。
我只是不能让这样一个好主意不起眼。OP可能比带给你的想法更糟糕。
最新型号代码还提供了粘贴在爬虫空间中的除湿器的替代方案。但爬行空间ERV回报将提供更好的气味和氡控制。
Looking into costs and radon mitigation I believe I will go with a option 2.1 with a exhaust to outdoors and a transfer grille from main floor to crawl space for now and comfort, time, and money calls for it do an ERV system later. Thanks for the help guys.
我会通过一个在线负载计算器（CoolCalc或LoadCalc.ent）运行您的位置。
最小的设计为基础,我想这四个zone multi split would be about 2x oversized at design conditions. This means it would be ridiculously oversized most of the time which will cause it to cycle. This tends to increase energy use by a fair bit and will cause comfort issues on the smaller zones as they tend to get overheated or overcooled as refrigerant is bypassed through them.
If your budget is tight, the best bet is a single wallmount in the living space and resistance heat for the bedrooms. During the day, as long as the doors are open, most of the heat will be from the mini split so the resistance heat will not need to run much.
There is no need for propane or other backup. A decent cold climate mini split will easily heat your place. Add in the resistance heat in the bedrooms, you'll have enough to make it through even the worst polar vortex.
如果这个选项不起作用，下一个最好的东西是整个房子的单管热泵。
This can be mounted in the crawlspace with simple runs to each room. You can even make a nice access hatch for it from the main floor by framing a large opening in the floor of closet of the guest bedroom and putting the floor there on a hinge.
您可以查看MRCool的Universal或Midea DLCSRBH24AAK / DLFSAAH24XAK，费用小于您的四个区域多分裂。
As for ventilation, something like a Panasonic Intellibalance 100 is not much more than the cost of two decent bathroom exhaust fans. Besides the energy efficiency improvement, this will give you much better indoor air quality. You really have to experience it, it is hard to describe how nice it is to walk into your home and to have the air always feel fresh.