Manual S Performance Data
The Manual S Performance Data page lets you enter manufacturer performance data for your air conditioner or heat pump. You are allowed to enter net adjusted capacity data that you have obtained elsewhere or you can enter multiple performance data points for your equipment such that this page can perform an interpolation on those data and calculate the resulting net total capacity, sensible capacity and power input for your equipment at your design conditions.
Performing equipment selection per Manual S requires that you have the sensible and latent loads for your project, along with the indoor and outdoor temperature conditions. If you are calculating these loads through Rhvac Online, you should finish entering all of the rooms in your project before going to this page. If you have obtained the load information in some other way outside of Rhvac Online, you can still use this page by checking Allow Custom in the Loads section of this page.
The Manual S Performance Data report is flexible in that it can be created with varying detail. If every possible adjustment is used in interpolating and calculating net capacity values for a unit, up to 48 values can be included in the interpolation table portion of the report, and it is even possible to select that the interpolation values not be printed at all.
There is also a Simple Mode option that you can select that does not require multiple data points to be entered in the Interpolation Values grid. When in simple mode, there are only two values that need to be entered into the Interpolation Values grid, and those are the total capacity of the unit and the sensible capacity of the unit. The power input field is optional. See more details below about Simple Mode.
Current System: Specifies the system number for the performance data you want to edit.
Name: Specifies the name you want to see in reports for the current system.
Equipment was selected according to Manual S: If you have in fact selected the current system's equipment in accordance with the procedures given in the ACCA Manual S publication, you can check this box to add a paragraph to the System Equipment Data and System Room Load Summary reports stating that. The paragraph will also include a list of data for the current system required by Manual S to select equipment. If you have not read Manual S from ACCA or have not followed its guidelines in selecting your equipment, then you should not check the box.
Units: Specifies whether you want to use the same units (English or Metric) for the performance data as you selected for your project (Default), or whether you want to change it. This input is provided in case the performance data you receive from the manufacturer happens to not be in the same units in which you entered your project.
Capacity Units: If your manufacturer's performance data show capacities as MBtuh (1000 Btuh) then select that option. Otherwise, select Btuh. All capacities shown on the page, including those in the Heating Equipment and Cooling Equipment area, will be converted as needed to match your selection.
The inputs in this area are the same as those on the Equipment Data page, and are used primarily to document your project. They don't have any effect on the load calculations or the Manual S calculations. The optional capacity values are initially zero, but are provided in case you are able to obtain adjusted capacity values elsewhere, such as from a manufacturer's performance data program or web app.
Show More Heating [Cooling] Equipment Inputs: These buttons toggle whether you can see the whole list of inputs that document your equipment or just a few of the more important ones, such as the capacity inputs.
Sensible Gain, Latent Gain, Total Gain, Sensible Loss, Heating Entering Dry Bulb, Heating Airflow: These are the calculated values for the current system, unless you check the Allow Custom box, which allows you to enter custom values that you may have obtained from elsewhere.
Load SHR: Displays the sensible heat ratio of the total load (sensible / (sensible + latent)) on the cooling coil, including both supply and return side loads.
Allow Custom: When checked, the inputs in this section (except Load SHR) are enabled, and let you specify the load of the system for which you are doing a Manual S calculation. When unchecked, they are grayed out and disabled, and show the calculated load for the current system.
Outdoor Wet Bulb, Indoor Dry Bulb, etc.: All of these inputs are normally entered on other pages in the project, so if you change them here they will change on those other pages as well.
Outdoor Dry Bulb, Supply Airflow, Entering Wet Bulb, Entering Dry Bulb: Displays the values from the current project that are needed for the Design inputs in the Interpolation Conditions frame, below. The entering dry and wet bulb temperatures are defined as being related to the cooling coil. If you have not calculated the loads with Rhvac Online these values will initially be zero.
Copy All to Design: Copies the values from these inputs into the Design inputs in the Interpolation Conditions frame, below. Use this when you have non zero values to copy. Otherwise, you will need to enter appropriate values in the Interpolation Conditions frame.
Interpolate Outdoor Dry Bulb, Interpolate Supply Air Flow, Interpolate Entering Wet Bulb, Interpolate Entering Dry Bulb checkboxes: These checkboxes allow you to specify which parameters will be used in the interpolation process for calculating the adjusted capacity of a unit. The net capacity of a unit varies with changes in these values. Only check these boxes if you have expanded ratings data available for your unit. See the five examples available if you have these data. You are free to check any combination of these boxes, including none of them if you have no expanded ratings data available, or if you already have adjusted capacity values that you have obtained elsewhere. When you select a unit from the manufacturer databases in Rhvac Online, remember that this information is only the AHRI nominal rated data for the selected unit. There is no underlying expanded ratings information available from the AHRI databases. Expanded ratings data are only available directly from each manufacturer. Use the Simple Mode (explained below) if you have no expanded ratings data available.
Design, Next Lower, Next Higher: The Design column specifies the actual design conditions for the current system in the current project for which you want to find interpolation results. Enter these values directly or use the Copy All to Design button above to automatically copy the appropriate values into the Design inputs. Each of the four inputs in the Design column must be filled in for the calculations to work. The Next Lower and Next Higher columns need only be filled in when you have checked the box for that row. Values for the next lower and next higher columns are obtained from the expanded data tables for your equipment. See the Overview for guidance on how to obtain those data. See also the five examples that show how to use expanded ratings data. These data may not be available to you, and thus there is a Simple Mode that does not require expanded ratings data.
Calculate Entering Coil Point: If loads are being calculated with Rhvac Online, this selection will not be needed. It is sometimes needed when using custom loads, and will take you to the Calculate Entering Coil Condition page, where you can enter the parameters used to determine the entering cooling coil dry bulb and wet bulb temperatures. Normally, you will only need to click this button if you checked the "Allow Custom" checkbox earlier on this page.
Include on Manual S report: If this box is checked, when you print the Manual S Performance Data report the Interpolation Values you enter in these boxes will be included on the report.
Each of the inputs in these rows specifies a value that corresponds to the gray EWB (entering cooling coil wet bulb temperature), Air Flow and ODB (outdoor dry bulb temperature) inputs directly to the left. If in Simple Mode, only one total capacity value and one sensible capacity value have to be entered for just the top row.
Total Capacity: Specifies the sensible plus latent capacity of the unit at the indicated condition. Note that the total capacity remains the same even if you have a range of entering cooling coil dry bulb (EDB) temperatures specified. For two different EDB values, the sensible and latent capacities change, but still add up to the same total capacity. The total capacity will vary with different outdoor dry bulb temperatures, airflow values, and different cooling coil entering wet bulb (EWB) temperatures.
Power Input: Specifies the power input of the unit at the indicated condition. The power inputs are not required if you only want to get interpolation results for the capacity of the unit. You are free to leave the power input at zero, and if you do, power inputs will not be included in the reports.
S/T EDB Low, S/T EDB High: S/T is the sensible to total heat ratio (sensible / (sensible + latent)). EDB is the entering cooling coil dry bulb temperature. The actual EDB of your project will typically have a value between the table values from your expanded ratings data. Thus, there will be an EDB Low and EDB High value that you will take from the expanded ratings data. See the examples for more information on this. Some manufacturers publish the sensible capacity values, and some specify only the total capacity, and then the sensible to total ratio.
Sensible Capacity: Specifies the sensible capacity of the unit at the indicated condition. Some manufacturers publish the sensible capacity values and some specify only the total capacity and then the sensible to total ratio.
Simple Mode is when you have all the "Interpolate..." checkboxes unchecked, leaving only the top row of the Interpolation Values grid with any enabled textboxes. This mode sets things up to accommodate nominal capacity data or adjusted capacity data that you may have obtained elsewhere, such as from a manufacturer's performance data program or web app.
Set to Simple Mode: Unchecks all the "Interpolate..." checkboxes so you only have to enter one row of data.
Copy Nominal: Copies the nominal sensible and total capacity input values from the Cooling Equipment inputs to the top row of the Interpolation Values grid. The values that will be copied are shown to the right, under Sensible and Total.
Copy Adjusted: Same as "Copy Nominal," except copies the "adjusted" capacity values instead of the nominal values.
Refresh Button: If you have changed the nominal or adjusted values under Cooling Equipment since opening this page, you can click Refresh to ensure that the latest values are shown in the gray boxes under Sensible and Total.
Elevation Derating: Specifies any manufacturer supplied elevation derating factor you want to apply to the results. The total and sensible capacities in the Interpolation Results area will be multiplied by the value you enter here.
Miscellaneous: Specifies any additional derating factor supplied by the manufacturer that you want to be applied to the results. The total and sensible capacities in the Interpolation Results area will be multiplied by the value you enter here.
Direct (Direct Capacity Adjustment): If the manufacturer provides a direct capacity adjustment, you can enter it here. The value may be positive or negative. To reduce the capacity enter a negative number; to increase capacity enter a positive number. The value you enter here will be added to the final result, and will be reflected in the Total Capacity and Sensible Capacity boxes below this input.
Direct Adjustment to Sensible (Keeps Total the Same): If the manufacturer provides a direct adjustment to the sensible capacity, you can enter it here. The value may be positive or negative. To reduce the capacity enter a negative number; to increase capacity enter a positive number. The value you enter here will be used to adjust the sensible capacity and the latent capacity, while the total capacity will remain the same. If sensible goes up, latent goes down, and vice-versa.
Some manufacturers, such as Carrier, provide this kind of adjustment as a formula where you determine how much sensible capacity to add or subtract based on the number of degrees you are away from a given indoor dry bulb temperature, as well as what the supply airflow is.
Total Capacity, Sensible Capacity: If in Simple Mode, the total and sensible capacities entered in the Interpolation Values grid are passed on unadjusted to the interpolation results. If more than one row is filled out in the Interpolation Values Grid (meaning that you are not in Simple Mode), the capacity values in the interpolation results will reflect the interpolation effects of all the values entered in the grid.
Load and Cap/Load %: If Allow Custom is not checked, the Load column will show total and sensible loads as calculated by Rhvac Online. If Allow Custom is checked, the loads shown will be what you have directly entered as the total and sensible loads. The Cap./Load % shows the total and sensible equipment capacity values as a percent of their respective loads. These percent values should range from 100 to 125%, which would indicate that your equipment has sufficient capacity.
Power Input: The power input value is not an important part of a Manual S calculation. It is only a point of interest as pertains to the efficiency of equipment, but it does not have any bearing on whether a unit will meet the total and sensible loads of your project. As such, it is perfectly acceptable for this value to be zero, and if it is, nothing concerning the power input of the equipment will be printed in the reports.