答复

1. Expert Member
   Zephyr7.|Jun 21, 2019 08:15pm|＃1

   管道运行多长时间，它位于条件或无条件的空间内？如果它是一个在条件空间的短跑，那就是额外绝缘将具有最低利益的情况。如果运行长期和无条件的空间（如没有绝缘的阁楼），那就是您看到最高益处的情况。

   Duct profiles with a high ratio of surface area to contained cross sectional area will also see more benefit than ducts with a lower ratio. That basically means skinny rectangular ducts will see more benefit than square or circular ducts.

   BTW, the usual commercial method to insulate large ducts is to attach rigid fiberglass panels using nail-like fasteners that are tack welded to the duct with an arc welder. Seams are then usually taped for a neat appearance. This type of insulating work isn’t normally done in residential settings, but sometimes it can make sense.

   Bill

1. 
   瑞安Welch|Jun 25, 2019 01:26pm|＃4

   Thanks, Bill. It's in an unconditioned space (hot attic in the SE). I'm going to take the supply temps in various areas of the house this week and I'll report back with the differences at the longer runs. I did notice that I have some of the older gray ducts (not shiny) that have started to separate on the outside (ducts in tact though). The R-Value is only 4 and I know you can get double now. Why do these old ones split? Getting baked in the attic??

2. Expert Member
   马尔科姆泰勒|2019年6月21日10:14 PM|＃2

   瑞安,

   无论您最终绝缘，空气密封，还是重新空气密封导管都花了很好的花费。

3. 
   jrpritchard|2019年6月22日12:21 AM|＃3

   瑞安

   It depends on the type of variations you are seeing. If the temp dissapates quickly as you move down the trunk then insulation might help. If you are seeing the variations randomly it is most likely a sizing or leakage issue. Either way Malcom is correct - focus on air sealing which should give you more CFMs which should allow you to balance things out a little bit. In my experience wrapping ducts in a retrofit situation especially in an attic can be difficult. We have had better luck with the buble type wraps like you have show in conjunction with a good spray adhesive as opposed to the foil backed fiberglass wraps that are out there. Better yet - have 2-3” of open cell sprayed on your ducts. Air sealed and insulated done in one step. You can also have them hit the boots where they penetrate the ceiling which is typically a difficult area to seal and insulated. Our labor and material for an attic job is typically comparable to a small spray job that can be done in one mobilization

4. Expert Member
   armando cobo.|Jun 25, 2019 01:38pm|＃5

   In CZ1-3, the code now allows to install R13 min. insulation wrapping the ducts in ventilated attics to avoid condensation issues. We install one layer of R8+ one layer of R6, giving us total R14 in CZ3. All joints still need to be sealed with mastic.

1. 
   瑞安Welch|2019年6月25日01:52 PM|＃6

   谢谢armando - 我读到最近并听说你可以把它们埋葬在那个r13的价值。去年我有一个承包商，只是想在我的阁楼里的旧R4.5弯曲管道上吹出。我担心凝结。

   你如何用柔性完成那个r13？您是否使用R-8 Flex然后再次用R6包裹包裹？浓缩物之间的蒸汽屏障是否会？

5. Expert Member
   armando cobo.|2019年6月25日01:59 PM|＃7

   我使用2015/2018代码。阅读美国建筑解决方案中心的代码合规性：埋在阁楼绝缘和封装的管道。向下滚动。你有一些选择。
   https://basc.pnnl.gov/resource-guides/ducts-buried-attic- sinsulation-and-encapsored#quicktabs-guides=6
   Sorry, I didn't answered your question. Yes, and we install metal ducts only, but first seal the ducts with mastic, then install the R8, SEAL IT, and then wrap it with R6 SEALED! Our HVAC guys have an awesome duct tape and then they cover it with mastic.

1. 
   瑞安Welch|Jun 27, 2019 04:56pm|＃10

   我确定的金属管道巨大差异！希望我有它们！

6. Expert Member
   达娜·迪斯特|2019年6月25日02:18 PM|＃8

   >"Yes, but first seal the ducts with mastic, then install the R8, SEAL IT, and then wrap it with R6 SEALED! Our HVAC guys have an awesome duct tape and then they cover it with mastic."

   YES YES YES !!!

   空气密封管道将为舒适性问题做更多，而不是任何额外的隔热管道，这绝对是第一步！在管道上施加更高的r会提高效率（这是值得的），但通常不会制造或打破舒适问题。空气密封每个接缝和带有管道乳香的接缝，即使它看起来很紧。

   毕竟是初步的问题是：

   >"Will this help reduce the current supply temp variations throughout the house? "

   回答: Maybe, not usually, but still "worth it."

   供应温度变化是比绝缘体更大的流动。通常，流动在返回路径侧受到限制。能量星管道系统足够好，空间到房间压力差异永远不会大于3帕斯卡，或0.012“水柱。这必须是所有空气处理速度，房间门打开/关闭。是任何”也是如此温暖的“房间门关闭，没有专用的回流寄存器或跳转管道，以保持压力差异低？

1. 
   瑞安Welch|2019年6月27日04:55 PM|＃9

   嗨达娜
   The rooms that do get "doored off" at night are the small bedrooms that are often too cold during the summer. The warmer rooms are at the end of the trunk line. I did find out that the flex duck to them is the old gray R4 flex line, so I'm putting R8 flex on them and see if that helps. The temps on a warm day are usually 5 degrees warmer at the supply ducts at the end of the trunk line.

   I probably need more return vents. I have two at each ends of the hallway. The smaller doored off rooms actually get too cold in the summer!

1. Expert Member
   Zephyr7.|2019年6月27日07:15 PM|＃11

   尽量尽可能地伸直柔性管，或者更好，用刚性金属管更换。空气流量更多地涉及管道的尺寸和型（刚性或柔性）而不是绝缘。

   破裂的旧管道可能是某种塑料材料。较旧的塑料会变脆，有时随着年龄缩小，这将导致它们裂开和分开。

   Bill