排除凝聚锅炉
A few years ago I bought a house outside Boston with a failing oil based hot water baseboard system. House was built in 1915, original windows, ~4-5 inches of blown in fiberglass in the attic, and blown in fiberglass in the walls. House is about 1700 sq feet composed of two floors, 1 zone for each. We promptly redid much of the second floor, all new Rockwool in the walls, new windows, R62 in the attic and everything air sealed.
We got three quotes to switch to gas from local well reviewed heating/cooling contractors and all of them recommended the Navien NCB-240E. Unfortunately, I didn’t really understand much about heating/cooling at the time, but I now understand that this system is not a great fit because its way oversized on the heat side and can’t modulate low enough.
I have the outdoor reset installed, but the last two years its been just running at 180 degrees, which I would like to change. I read //m.etiketa4.com/question/sizing-a-modulating-condensing-boiler but I am not sure I fully grasp a path forward.
For example, my second floor zone is a series run around the entire perimeter of the house. It’s about 160 feet of copper from the boiler, of which ~58 feet is finned. I used cool calc and the slant fin tool and both of them came out at about 13,000 BTU as my heat load for that zone and the Navien can only modulate down to 17,000 BTU. Putting aside that modulation, if I understand this correctly, when its running at 180 degrees, I am probably putting out about 34-35K BTU which is way way too much, causing my boiler to short cycle.
所以我的问题是，我是否有任何希望挽救我使用室外重置的能力，并在只有我的二楼呼叫时，我的锅炉凝聚力？
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由气候和房屋部件组织的一千个建筑细节的集合
答复
听起来像您的户外重置不是正确的。还要调查分区，减少但不会完全关闭区域。还要考虑将缓冲罐添加到从锅炉负载（即，减少循环）中的建筑物负载。
是的Jon R，我的户外重置目前正在休息，同时调查如何在这个秋季打开它，我意识到我的二楼区域对于锅炉来说太小。缓冲罐似乎是一个有趣的想法。如果有人在波士顿地区读这篇文章并了解了一个我可以来评估这一点的好公司，请告诉我。我用过的公司用安装工艺做了一件很棒的工作（根据我退休的水暖邻居），但我不确定我相信他们对解决大小写问题的判断。
在那个带有15k Btu负载的情况下，Dana Dorsett的线程也有一些评论，只有2k的浪费BTU是理想的，而且也不是一个巨大的交易，但在我的情况下它会更像4-5kBTU，但我认为假设我无法低于130度的水。
With a two story structure, most of your house heat comes from the main floor. The generally means the main floor zone runs more often.
In your case, the simplest solution would be to interlock the 2nd floor zone to the main floor. This way, the 2nd floor zone can only call for heat if the main floor is running but the main floor can run independent. This still gives you independent control of temperature in both places without having to worry about short cycling.
This assumes the main floor has enough radiation capacity or has high mass rads to avoid short cycling from outdoor reset.
这应该是区域阀/区控制器上的一个相当简单的重线。
Ask your service tech if it would be possible to use a smaller oil jet that would reduce the BTU output. There is a limit to how small you can go.
Walta
有些谨慎的调整，我认为你甚至可以获得你的二楼区域运行顺利。可能不会得到很多凝结。即使你没有凝结，你将通过减少180的温度来获得一些效率。您应该能够达到130F和150F之间的均衡。如果您低于发射器不会快速释放热量，导致温度上升到上方，锅炉将循环。
You should be able to setup your on/off differential to allow some temperature rise above set point without immediately shutting off. (so the boiler will start at say 10F below set point and run until 10F deg 15F over.) So make sure that if your Outdoor reset goes down to 120F, that the differential allows it to float to 140F before shutting off. The idea is that you want to reach equilibrium rather than shut off and short cycle.
You may find that you have to be conservative how low the ODR goes. If you add mass with a buffer tank you can reduce the temperatures and still have reasonable cycling.
A small buffer tank would go a long way.
Even a small electric tank installed as a two pipe buffer would be good since the ports are smallish.https://www.lochinvaru.com/resource/calculator/buffer.html
Also, make sure you aren't over-pumped, that will drive your return water temp upwards.
调整的参数是：
- the burner-on temp (set to 10F-15F, default is 4F)
-burner-off temp (set to 10F-15F, default is 5F)
-Anti-Fast cycling time (set to 10 minutes, default is 3)
-reduce the max space heating capacity to 50% which is as low as it goes.
留下升压功能。
Set your outdoor reset to 1. (fin tube) to start. You may be able to tune it downwards.
https://www.navieninc.com/downloads/ncb-e-manuals-installation-manual-en
Josh Durston Thanks for the detailed reply. Sorry for taking so long to reply, I really appreciate it. My newborn has me busy :)
所以我在我的一楼里做了一个Hearloss Calc，它有一吨窗户，我还没有更换它们，所以它比第二次泄漏。BTU要求如28k。一旦我重做窗户，还要把我的未加热的3季房间带入信封，它大约是32k。
I already changed my water temp to 145, although now that I did the calc, I think I have about 72 feet of baseboard on the first floor, so I may need to increase it up to 150-155 to make sure I can adequately get the first floor.
Using that calculator, it seems like you are right that even a small tank would help the second floor zone. Something as small as <25 gallons would work.
我会检查泵送。我需要看看Navien是否在其菜单中提供流量。我知道每个区域都有一个泵，我认为它们都设置为低，但我会仔细检查。
You boiler has a built in primary pump, I'm not sure if it's variable speed or not.
但我建议安装系统供应传感器以测量混纺供应而不是锅炉放电。如果二次流量高于锅炉可以补偿锅炉可以补偿那种方式。如果它们换热，我会将区域留在低温下，锅炉流量由内部泵确定而不是区域泵。区域泵只需要移动足够的水来加热区域。
如果您的流量太高，您可以安装各种平衡设备。高流量会升温，但是由于您的RWT可能会回来，因此您将牺牲锅炉效率。如果似乎你的流量很高，你可以将手动阀一点进行实验。注意您只需高速SWT温度和负载即可获得高度增量。随着您降低温度，Delta也会减少（假设恒定流量）。
你真的想尽可能低地获得你的RWT（120f或更低）。我甚至可能会尝试在RWT控制模式（而不是供应）中运行锅炉。（它仍将将供应温度限制为高限制。）有一个倾斜度来改变这一点（101F-147F RWT的翅片管户外复位设置可能是一个很好的起点）。跑步rwt有点补偿了太多的流量。
阿科斯' suggestion about interlocking the second floor to only run while the first is calling is a good idea. It may let you run much lower temperatures without short cycling the boiler. But I would play with the boiler thresholds and cycling parameters a bit first, to see if it runs ok without cycling.
理想情况下你想duratio锅炉运行n of a heating call, or if that's not possible close to 10 minutes would be reasonable target. Your min water temperature will probably be determined by short cycling (unless you add a tank), and your top temperature will be determined by your highest load on a cold day. Reduce both until your run into short cycling or comfort issues.
Hi Walta, to clarify, I have a gas boiler, I switched away from Oil.