对老美的家庭温控系统很是不了解，特别是mutliststage系统的控制逻辑很是不了解，希望有了解的网友能帮助解答一下。
以下是对Nset官网关于What is a multistage system?的翻译，请大家指正，谢谢！
What is a multistage system?
什么是多级系统。
Multistage heating and cooling systems help households use less energy. The Nest Learning Thermostat is compatible with up to three stages of conventional heating and two stages of cooling.
多级加热和制冷系统帮助家庭使用更少的能源。Nest学习型恒温器兼容高达3级传统的加热和2级制冷。
Multistage systems use multiple levels of heating or cooling to save energy. Like a dimmer on a light switch, they adjust the level of heating or cooling to the temperature you set. These efficient systems use the lowest level
of heating or cooling needed and only use higher levels for those really freezing or scorching days.
Using lower levels of heating or cooling is more efficient because the system doesn’t need to turn on and off as often to maintain a constant temperature.
多级系统使用多级加热或冷却，以节省能源。就像电灯开关或者调光器，它们调节加热或冷却的水平到你设定的温度。这些高效的系统在必需的时候使用最低的加热或冷却水平，只有在真正冰冻或者炙热天才使用最高级别水平。 使用低级别的加热或冷却更高效，因为该系统并不需要经常打开和关闭来维持一个恒定的温度。
Most older systems are single-stage, on-or-off systems with only one level of heating or cooling.
大多数旧系统为单级系统，开/关系统只有一级的加热或者制冷。
Does the Nest Thermostat support multistage systems?
请问Nest恒温器支持多级系统吗？
The 2nd generation Nest Learning Thermostat supports up to three stages of heating and two stages of cooling for conventional systems, and two stages of heating and cooling with auxiliary heat for heat pumps.
在第二代Nest学习型恒温加热对传统系统支持多达三个级别和冷却的两个级别，还有2级加热和制冷并有对加热泵的辅助制热。
The 1st generation Nest Learning Thermostat supported two stages of heating and one stage of cooling for conventional systems, and heat pumps with auxiliary heat.
第一代Nest学习型恒温器为传统系统支持2级加热和1级制冷，加热泵支持辅助加热。
How can I tell if I have a multistage system?
我怎么才能知道我有一个多级系统?
Most multistage systems can be recognized by the wires attached to the thermostat. Conventional single stage systems will only have one wire for heating (W1) and one wire for cooling (Y1). Single stage heat pumps only have Y1 for
both heating and cooling.
大多数多级系统可以通过连接到恒温器的电线来识别。传统的单级系统将只有1条加热线（W1）和1条制冷线（Y1）。单级系统的加热泵只有使用Y1来同时完成加热和制冷的功能。
Multistage systems will have more than one heating or cooling wire. For example, three stage conventional heat uses wires W1, W2, and W3; Two stage cooling or heat pumps use Y1 and Y2. Some heat pumps also have auxiliary heat,
an additional stage of heating that is only used when the heat pump compressor can’t keep up with cold weather conditions.
多级系统将拥有超过1个制热或制冷接线。例如，3级传统制热使用W1、W2、W3线，2级制冷或加热泵使用Y1和Y2。一些加热泵也使用辅助加热，1个附加的制热级别只有在泵压缩机更不上冷天气的情况下使用。
What’s the difference between multistage systems and zoned systems?
多级系统和分区系统之间的区别是什么？
Multistage systems are different from zoned systems. Zoning has nothing to do with your system or connected wires. Instead, zoning is a way to heat or cool different areas (“zones”) of the home separately, either using separate systems or using dampers in the
ductwork to guide hot air to each zone.
多级系统不同于分区系统。分区系统与你的系统或者链接的电线无关。取而代之的，分区系统是单向加热或制冷区别于家里分别独立的区域（多个分区），使用单独的系统或者使用管道的调节阀来导流热空气到每个区域。
What is a multistage system?什么是多级系统？