Heat Pump Sanity Check – Empirical load versus NEEP tables
TL;DR; – I would value a gut check about whether I am correctly/realistically interpreting the output I can expect from a given heat pump at a given temperature based on the data from our friends at neep.org .
我处于设备选择的最后阶段，用于使我们的主炉/交流系统电气化。
在较早的帖子中，我总结了一些准备工作，我们为通过靶向泡沫和一些致密的包装纤维素降低了整体负载。链接在这里：
The result is that this morning, here in Chicago, it’s a windy and bitterly cold 10F and my Nest based instrumentation is indicating our existing furnace had a peak averaged output, just before the sun came up, of around 19K BTU/hr. This is for the “downstairs” furnace located in the basement. We have two independent HVAC systems, but 2 years worth of data suggests that during the winter, the first floor/basement system carries over 90% of the load. The house is 1500 sf (or 2100 sf if you include the foamed but unfinished basement).
The downstairs/basement furnace is a ducted natural gas unit. The registers all feed into various locations on the first floor which is actually a single “great room” covering the entryway, kitchen, dining room and living room. (As a single stage 80K BTU/hr unit, it is also profoundly over sized.)
I have for some time, had my eye on a Fujitsu cold climate single head unit with a nominal/rated output of 15K. Here is its NEEP data page:
https://ashp.neep.org/#！/product/25337
The NEEP data above indicates the unit can actually output 20,500 BTU/hr at 5F (with a COP just above 2). I’d be perfectly happy to set today’s conditions as my rough design load, and am prepared to cover any additional heat needed at lower temperatures with some combination of space heaters and our wood stove. My simplified understanding is to compare this to my measured heat demand this morning of 19,000 BTU/hr at 10F and to say “I’m good. Let’s go.”
我缺少什么吗？
这个单元（以及其他提供低温操作的供应商的类似大小的供应商）似乎是我所能获得的“最大”东西，在更高温度下，仍具有良好/高效的低输出操作，但仍具有良好的转换比率。因此，如果可以的话，我很想使它起作用。
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Replies
There are many units that have much better COP's and turn down ratios than that Fujitsu. Dig around the NEEP site and you will find some units that have COP's of 2.5-3 at 5 degrees. Take a look at this LG and Carrier for example.
https://ashp.neep.org/#!/product/25944
https://ashp.neep.org/#!/product/26721
Looking at the full specs, I'm not convinced either of those are better than the Fujitsu. The COP of the LG is not that great at more modest temps in heating mode, and it's abysmal in cooling mode below nominal output. The HSPF is a pretty good indicator of overall efficiency in heating mode, and both the LG and Carrier are lower than the Fujitsu, especially the Carrier at 10.3 is quite poor.
高输出处的改善COP令人着迷。我确实记得这里的一些成员解释了HSPF之间的差异，而HSPF是相当规定的官方和官方的，而不是更详细的NEEP人物，而AIUI在测试条件方面附带的字符串较少。
In any case, I'm still keen to hear some feedback on the other half of the question, which is whether anyone happens to know if the "Max" output figures can be viewed as a reliable/sustained output figure. (I suppose one particular concern is that these figures represent the output when heating but don't reflect the unavoidable periods of time where the unit is running a defrost cycle.)
我没有专家，但我相信最大输出没有考虑到解冻周期。
作为参考，我今年秋天在我家的一楼安装了15k楼层的富士通，并于今年冬天到目前为止已经加热了整个房屋。我住在底特律附近，2层家，手动J热负载约23 kbtu/hr，在5 f。
我计划安装一个导管装置(9 rlfcd)上for the upstairs, but this is for AC more than heat.