In this lesson we're going to cover the addition of an energy recovery device. We're going to continue from the last lesson and add this to our dedicated outdoor air system, but the process would be the same, whether or not it was a dedicated outdoor air system. The only reason we're adding this to the dedicated outdoor air system is because it's a common question. To start, the first thing we want to do is go to the air-side HVAC module. All we have to do is click the dedicated outdoor air system (you could click any other system you were adding this to). We open this up and select outside air. We have several heat recovery options. We're going to just have one layer-- that's the most common. We're going to select that there's an ERV device installed. We select yes. This is going to prompt us with the type, and let's just go with the sensible heat exchanger. We click done. It fills out the effectiveness, the air film resistance, and the air film resistance exponent. These are just defaults. The two bottom values are often hard to find. They could be set by the manufacturer, but please note that these only matter when the air flow changes drastically. If you have laminar flow, this exponential value will be zero because as the flow changes, it will stay approximately laminar In addition to heat recovery one, we could add a second stage of heat recovery. Though this gets increasingly complex. For now, let's look at what the defaults do. If we select a sensible heat exchanger, we get cross flow, which is the most common. This means that we have exhaust air crossing one side of the wheel where the ventilation air, the fresh outdoor air, is coming in on the other side of the wheel. If we selected a heat pipe, we have to change these values. Let's just say it has a .5 effectiveness and the ratio was .5 and .2. We're illustrating that the default configuration is counter flow. There's one other thing in here that's really important, and it's the control sequence. The default operation is when fans are on, which makes sense for a dedicated outdoor air system. However, if you have an economizer, this means that you're going to be operating the energy wheel when the economizer is on. What's typically a better control sequence is to select when minimum outdoor air. This happens when you have your required amount of outdoor air by code operating, the energy recovery wheel will operate. So if you do go into economizer mode, the energy recovery wheel, or the heat pipe, will effectively be by-passed.