ERV在封装的地下室/爬网空间中
你好，I have a 3,600 sqft basement/crawlspace that I recently enclosed with 3” of spray foam from the floor to the rim joists. The areas are a combo of poured concrete and rat slabs. The area is pretty complex so adding some type of poly vapor is pretty difficult. The original buildings plan shows that a poly vapor barrier was added below the rat slab and poured area. I have a variety of mechanicals down there, hyrdoair oil furnace, hot water heater, 3 air handlers. There’s a mechanically controlled fresh air supply that fires anytime the furnace or hot water heater call for heat. I’ve got a Santa Fe force system that keeps the basement below 45 in the summer, and don’t see any water issues.
Since encapsulating my radon levels went up, so I had someone install a depressurization sub slab system with two drilled entry points that have lowered the levels. This system only covers roughly half of the basement space because of the length of the run, so the guy suggested to do a wait and see approach to see if we needed another one on the other side where the bedrooms are. The levels at the time tested at .7 and .8, and I’ve done a long term that averaged at .75 . I decided to retest this winter in the same spots, and have a digital unit as well, that both are now showing in the low 2s. Most people would say that’s not very high, but my family sleeps right above this crawlspace as it’s a 1 story ranch, and i don’t like the idea of the levels being on the fringe of potentially addressing, to “acceptable levels”.
My other concern is although the basement is nice and dry year round, there’s no sort of air flow in the crawlspace, so like it or not we get sort of a basement/crawl type of stagnant smell in the living space, and notice this more in the winter with the natural negative pressure, and the air essentially mixing with our living space.
I’ve done my own research and have a few options, I haven’t been able to find an HVAC professional that seems knowledgeable enough to provide a recommendation.
1.在房屋的另一侧安装另一个ra系统。不确定这是否会减少足够的值得值得的，不能解决气味/停滞的空气问题。
2. Install an ERV like this new Panasonic intelli-balance that would alllow me to balance or create slight pressurization in basement to partially help with the stack effect in Winter as well as dilute the crawlspace or smells, odors, while providing fresh air to space to also dilute or slow down the infiltration of radon. Would have slight energy penalty, but basement is so warm in Winter and dry in summer that heat in Winter wouldn’t have to work that much to offset 50-75 cfm of ERV filtered air, or dehumidifier having to work that hard in summer.
3. Maybe there’s another easier solution to reducing radon and dealing with smells. Is venting air from crawlspace out and creating a supply only from living space above into crawlspace enough to help with that? Or would I be creating a potential issue with all of my appliances that need makeup air. Plus exhausting would create negative air pressure which would allow radon to infiltrate the slab.
Please let me know if anyone has any words of wisdom or if they suggest anything that I’m missing? I though my about an ERV in the living space above, but I have 3 separate zones and the house is 31 years old with some insulation upgrades, but definitely not tight like a new house.
Thanks
Jason
Replies
杰森，
1. According to my training, you want to test radon in the lowest occupiable level of the house. In your case, the radon level in your crawl space is irrelevant. What you care about is the radon level in your bedroom. That's where you need to test for radon. If it's above actionable levels, everything is good. (You don't live in your crawl space.)
2. You don't want to pressurize your crawl space. (That will just send odors upstairs.) If anything, you want to depressurize your crawl space with an exhaust fan installed in your rim joist. You also need a makeup air source; this is usually done by installing a grille in the floor above the crawl space. This allows conditioned indoor air to enter the crawl, replacing the air leaving via the exhaust fan. Details here:Building an Unvented Crawl Space。
3.整个夏天运行圣达菲除湿机非常昂贵。如果这是我的爬行空间，即使工作很困难，我也会用聚乙烯和高质量的胶带在那里度过一天。如果这样做，则可以拔下除湿机的插头。
Hi Martin,
All testing was done on the main living space in our bedrooms and living room. We don’t inhabit the crawlspace or basement level so we don’t care what those levels would be. The EPA says to remove at 4 and above, but also suggests you monitor or consider removing between 2-4, while the WHO suggests remove at 2.7 . In either case we’d like to lower as much as possible. Most homes that read in the 2s on their lowest most occupied level will have levels half of that on their second floor where people sleep, so imagine that isn’t really a concern for them.
2. If I did an exhaust only system and provided make up air from above, wouldn’t I be creating a further negative pressure condition in the space? The air would be exhausted but wouldn’t that just pull harder from the slab below? If I pull 50cfm out of the crawlspace for example is that going to dilute the radon and smells that much that it won’t be simultaneously pulling in just as much radon from below?
3. I’d have to cover 3,600 sqft of space which is half on an angle and mixed back and forth between poured concrete basement space and rat slab that’s sits on bedrock and on an angle, there would be very little chance in getting a perfect sealed space. Doesn’t just one imperfection or crack in the area defeat the purpose? I’m less concerned with running the dehumidifier, it barely puts a dent in my electric bill and the space stays ultra dry. I’m more concerned about breathing in crawlspace air and radon levels.
What’s your take on adding an ERV down there besides having to run it? If plan on using between 50-75 cfm in the space which appears to take about 50-60 watts at most which isn’t very bad at all.
Thanks
Jason
杰森，
Q. "If I did an exhaust only system and provided make up air from above, wouldn’t I be creating a further negative pressure condition in the space?"
A. If you want to avoid odors in the space above, a negative pressure is desirable.
Q. "The air would be exhausted but wouldn’t that just pull harder from the slab below?"
答：有关此问题的数据尚无定论。有关该问题的详尽讨论，请参阅本文：仅排气通风系统和ra。
杰森，
问：“不仅在[聚乙烯]区域破坏了目的吗？”
A. No. When it comes to stopping moisture from migrating from the soil to the air above, the purpose of the polyethylene is to perform as a vapor barrier. The effectiveness of the vapor barrier is proportional to its area, so a polyethylene vapor barrier with 5% of the area consisting of holes is still 95% effective.
When it comes to a polyethylene layer used as part of a radon mitigation system, though, the purpose of the polyethylene is a little different. In that case, it's an air barrier. Your radon mitigation contractor should have been more concerned (it seems to me) with completing this polyethylene barrier when the radon mitigation system was installed.
你好，
This is getting slightly off topic, I’m asking about radon and air quality, I’m not having issues with humidity. I like using the dehumidifier I have in place, I don’t want to add another layer to the ground which will cost a ton in that space just to potentially replace the dehumidifier..
My question was about air quality and radon. The floor was not covered with anything for the radon system, the radon specialist used a pressure type Fan and drilled two holes into the basement section and crawlspace area. Basement is poured concrete, crawlspace with rat slab, building plans show a poly barrier underneath both areas. The radon system uses suction below the surfaces.
Do you have any clarity to the negative pressure situation I asked about by exhaust only as well as using an ERV?
谢谢
杰森，
Exhaust ventilation sometimes raises radon levels, and sometimes it lowers radon levels, and sometimes it leaves radon levels unaffected, as explained in the article I linked to. On balance, the evidence that exhaust ventilation is problematic from a radon perspective isn't very convincing.
When it comes to air quality, the exhaust fan (coupled with a makeup air grille in the floor above) will improve the air quality situation.
好的，对我来说很有意义，谢谢。也许我能做的就是在地下室中只有一个简单的排气风扇，如果ra级别上升，那么我只是让radon盖在房屋的另一侧添加另一个系统，然后将其添加。他最初提到，由于占地面积和不同的表面（混凝土倒在大鼠板旁边的地下室大爬行空间旁边，导致另一个混凝土倒入的地下室空间，旁边是另一个大鼠平板爬行空间），我可能需要另一个系统，具体取决于结果。这房子分为3个区域，厨房/餐饮/办公室，主要家庭房/客厅/游乐设施和卧室机翼。他能够为一个带有2个吸入点的系统进入一个系统，因为必须经过多长时间，无法到达卧室的机翼。我们随时可以在卧室的机翼上添加第二个系统，以使整个空间都得到解决，并从平板下方拉动ra。
How much CFM of exhaust would you recommend?
Basement/crawl footprint roughly 3,600 sqft, 4-5foot average height across the space. First floor living space roughly the same, some rooms have 20 foot ceilings, others 9ft.
如果我的机械设备位于化妆空气供应通风口旁边的地下室的一侧（当他们要求加热时，将新鲜空气从外部吹新鲜空气），我应该在空间的另一侧有这个排气风扇吗？这个化妆烤架应该离排气扇多远？做一个只允许空气以一种方式行驶的转移烧烤架之一吗？我猜想，在冬季，堆栈效果会越来越多，仅此排气系统并将空气推入居住空间吗？
杰森，
Q. "How much CFM of exhaust would you recommend? Basement/crawl footprint roughly 3,600 sq ft."
A. Once again, I'm going to refer you to the article I mentioned in my Response #1. Here is the link again:Building an Unvented Crawl Space。
文章指出，建筑法规的相关部分需要“每50平方英尺的爬网空间区域，以等于1 cfm的速率连续操作机械排气通风”。因此，您需要一个额定为72 CFM的排气风扇。
ok thanks, last question as it doesn't mention where in the article the actual grill should be placed in relation to where the transfer grill is. I'm guessing we need it to be a certain distance from the transfer correct? so that it doesn't just grab air directly from that area correct?
杰森，
排气扇和化妆空气格栅很可能allow you to get rid of your dehumidifier. That would save energy.
地板格栅的位置并不是关键 - 但远离排气扇可能比上方的要好。
如果它确实消除了它的需求，那就太好了。我能够依靠这样一个事实，即爬网空间上方的地板结构并非完全密封，因为没有空气紧密，所以如果我将72 cfm从空间中拉出，它将仅通过不完美而获得足够的以上？还是我需要特别需要进行新的切割和足够大的烤架以匹配所绘制的CFM？找到实际的排气风扇怎么样？我将其放在石油愤怒和热水加热器的另一侧，但是如果我将这个排气风扇放在我两个空气处理程序所在的另一侧，那会弄乱这些系统吗？我不想让他们吸引24/7的排气扇吸引空气或混乱，所以我猜我还需要从这些单元中宽恕它们吗？
谢谢
请注意，一年中的大部分时间都不会从上方做任何好事，而当交流运行时，它将增加您的交流费用。没有“自由除湿”。
目标是创建负面的地下压力以停止向上流动。上面地板上的化妆气格栅只意味着您必须浪费更多的能量才能达到相同的压力。除非有湿度问题，否则从上方流出是一件坏事。
If basement ducts are adequately sealed, this alone should solve your problems.
Don't worry much about negative room pressure undoing the radon mitigation system - the latter creates a much more negative pressure under most of the slab.
How many CFM - whatever is needed to get a pressure less than the space above.
我可以继续使用除湿机，我的目标不是减少其使用，因此，如果妆容只是允许爬行耗尽并允许更少的空气在楼上浸润，那么我想我会解决我的总体关注。
Martin,
By exhausting the crawlspace and adding the transfer grille from the living space above, aren't I also putting negative pressure on the living space above? Wouldn't I have the chance of pulling in smells from the chimneys into the living space or have issues if I'm usnig other appliances? or is the amount of CFM i'm exhausting not enough to be an issue? My house is 31 years old and isn't the tightest construction so its probably less of a concern compared to brand new construction.
杰森，
A fan that is rated at 72 cfm isn't moving much air -- it's about the same as (or a little more than) a typical bathroom exhaust fan. It won't depressurize your house the way a 1,200 cfm range hood fan would.
Especially if the fan is installed in a 3,600 basement / crawl space, it's not going to affect the pressure upstairs very much. Most basements have lots of cracks, so much of the makeup air will come from basement cracks, while some will come through the floor grille.
The idea is to encourage crawl space smells to travel somewhere other than the upstairs rooms.
Ok great thanks again for the advice. Will pick up one of those smaller variable speed exhaust fans and give it a try.
As far as the transfer grill..would it be alright to have one added into a built in cabinet floor? I have this wetbar that’s built right into the wall that has some cabinet doors, it would be very easy and unnoticeable if I just popped it in there. The doors aren’t sealed tight or anything, would that not be ideal? Would prefer to not have to put a whole in my floor or another hole in the wall if I could. Just to note, it is about 8 feet from the fireplace which may not be a good idea, but as you said it’s not that much force.
杰森，
Ideally, the grille should allow an airflow of 72 cfm with the fan running. I think that with the cabinet door closed, the grille you propose would have too much static pressure to work well.