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HVAC and Plumbing Piping Takeoff

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HVAC and Plumbing Piping Takeoff

In this article we’ll cover the new HVAC piping and plumbing material takeoff sheets which include labor units that were added to the MEP Academy Estimating Spreadsheets.

There are 4 new HVAC piping takeoff sheets, one for copper piping which includes ACR, Black steel pipe and fittings, Grooved fittings, and another for HVAC valves. For the Plumbing estimating spreadsheet there are 6 new sheets, one for Copper, CPVC, PEX, cast iron No-Hub, PVC DWV, and ABS DWV. For those with the combination HVAC and Plumbing estimating spreadsheet all 10 new tabs are available. On the menu click any of the buttons to take you to that page. Here we’ll click the HVAC copper piping page.

You can get a copy of this spreadsheet using the links at the end of this article.

We have provided material pricing and labor for some of the most used items. The page is very long and allows for you to add a lot more items if needed. The page starts with a list of copper pipe type “L” from ¼” to 8 inches, followed by ACR piping with a similar size range, and then soft copper. On the right side of the page are buttons that will take you quickly to that section of the page. For instance, if we click the button for copper Tee’s it jumps right to that section of the page.

MEP Academy Estimating Spreadsheet - HVAC Piping - Copper Material and Labor
MEP Academy Estimating Spreadsheet – HVAC Piping – Copper Material and Labor

If we want to get back to the top of the page just hit anyone of a dozen of these “back to menu” buttons located throughout the sheet. This takes us back to the top of the page where we can select another item. You always know what page you’re on by the highlighted  green button on the menu which shows that we’re on the HVAC copper page.

Manufacturers Price List

The prices listed here are the manufacturers list price as of the date indicated in this column. Some manufacturers change their price sheets monthly while others use the same one for years while adjusting the discount multiplier. The pricing shown can be changed when a new price sheet is available by just clicking on the link.

This takes us to Mueller’s price list page of their website where we can check to see what the current price sheet is. Estimators are responsible for ensuring that they’re always using the latest price list. There is the option to download an Excel or PDF version of the current price list or the previous one. Scrolling down the page we’ll find price list for fittings, refrigeration fittings and valves, PVC and ABS fittings and other products.

If we click on the PDF for copper piping this is what we’ll get.

We can see that this price sheet is effective August 4th, 2025, and that it supersedes the previous price sheet issued in July, 2025. Here we have prices for copper pipe type “K”, “L”, “M”, “DWV” and “ACR”.

List Price Sheet for Copper Piping from Mueller Streamline
List Price Sheet for Copper Piping from Mueller Streamline

Discount Multipliers

The estimator is responsible for maintaining discount multipliers for all pipe, valves and fittings. It is standard in the industry to know exactly how much of a discount you’re getting off the price list. This also makes it very easy to compare one supplier versus the next. If one supplier gives you a discount multiplier of 0.5 and the other 0.4, you can quickly determine which is the better deal.

Just put your discount multiplier here and all the material prices for this item will be adjusted to your discounted price. The spreadsheet allows you to use a different discount multiplier for various pipe, valves and fitting as they’ll vary accordingly.

Looking at the cast iron no-hub page we have listed the most used pipe and fittings. You can scroll down or just hit any of the buttons for any of the fittings you’re looking for, such as a sanitary tee. Once again you can click on the link to see what the current price sheet is for these fittings.

Vendor Website

Here is Charlotte pipes website where all their price sheets are located. If we click on the plus sign for cast iron a dropdown window opens revealing all their cast iron pipe and fitting price list. Here we have their List price sheet NH 124 in three versions, either Excel, PDF or HTML.

If we click on the PDF button it pops open the price list which we can download or just review online. We see that this price list became effective January 1, 2024, and was updated February 12, 2025.

Charlotte Pipe No-Hub Price List
Charlotte Pipe No-Hub Price List

We can see the type of fitting and the manufacturers’ part number which we have included in our estimating spreadsheet. Here we have couplings listed as part number NH 1.

You can also click on the HTML link, and it opens a version of their price list online. Here is the full list with the part number in the first column. Next is the size, and then the description. Descriptions such as the type of pipe or fitting, and the list price is in the far-right column. You can scroll down to see all the different cast iron fittings that they sell. Remember these are list prices and you’ll need to apply your discount multiplier to it to get your actual cost.

All the material cost and labor hours get carried forward to either the HVAC piping summary page or the Plumbing Summary page. This is where there is plenty of room for other systems or material types.

Get a Copy of this Estimating Spreadsheet using the following Links for the type you’re looking for.

HVAC & Plumbing Estimating Spreadsheet

Plumbing Estimating Spreadsheet

HVAC Estimating Spreadsheet

How Operating Room HVAC Systems Work

MEP Academy Instructor
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How Operating Room HVAC Systems Work

The HVAC system in a hospital operating room (OR) is far more than a climate control mechanism—it’s a front-line system for infection prevention, staff safety, and patient health. Designed in accordance with strict healthcare engineering standards such as ASHRAE 170-2021 and the Facility Guidelines Institute (FGI), OR HVAC systems are among the most regulated environments in building design.

In this article, we’ll break down everything you need to know into four key takeaways, focusing on how these systems are built to maintain sterile conditions, manage airflow, control contamination, and operate efficiently—all while staying code-compliant.

1. Air Changes per Hour

The primary purpose of an operating room HVAC system is to reduce the risk of surgical site infections (SSIs) by controlling airborne contaminants and maintaining a clean, stable environment.

According to ASHRAE Standard 170, 2021, an operating room must meet the following minimum conditions. Air Changes per Hour shall be a minimum 20 during occupied (surgical) conditions with a minimum of 4 Air changes per hour for outdoor (fresh) air.

The minimum of 4 air changes per hour from outdoor air, is to dilute airborne contaminants like bacteria, viruses, and aerosols generated during surgery. This high ventilation rate, mandated by ASHRAE Standard 170, 2021, ensures rapid removal of particles and maintains a clean environment, with HEPA filtration capturing 99.97% of particles greater than or equal to 0.3 microns.

How Operating Room HVAC Systems Work
How Operating Room HVAC Systems Work

Infections that result from airborne contamination can be deadly, studies show that up to 5% of patients develop SSI’s, contributing to thousands of preventable deaths annually. That’s why the HVAC system must maintain clean air, remove airborne particles, and create an environment that discourages microbial growth.

2. Airflow Patterns and HVAC Layout Protect the Sterile Field

The configuration and movement of air in an OR is not random, it’s engineered to flush contaminants away from the patient and surgical team. This is where airflow patterns and room layout come into play.

Per ASHRAE 170, 2021 and FGI Guidelines, supply air must be delivered using a unidirectional (laminar) flow system, located directly above the surgical table. Here’s how it works:

Supply air enters the room through laminar (unidirectional) ceiling diffusers, located directly above the surgical table in the sterile zone.

Air is filtered through HEPA filters. This clean, filtered air flows straight downward in a smooth column to protect the sterile field.

Return air grilles are positioned low on the walls away from the surgical zone, typically at opposite ends of the room, so that air exits after passing over the surgical zone.

This design creates a vertical airflow path from ceiling to floor minimizing turbulence and the spread of contaminants. The area directly above and around the patient is known as the sterile zone, while the outer edges of the room are considered non-sterile zones. HVAC airflow is engineered to always preserve that boundary.

3. Pressure Relationships Are Engineered to Prevent Contamination

An equally important part of OR HVAC design is managing room pressure relationships. In a surgical suite, air should always flow from the cleanest areas to the less clean areas. That means the operating room itself must be kept at a positive pressure relative to adjacent spaces.

Minimum Pressure of 0.01 Inches WG per ASHRAE 170 2021 (Hospital Operating Rooms)
Minimum Pressure of 0.01 Inches WG per ASHRAE 170 2021 (Hospital Operating Rooms)

According to ASHRAE 170, 2021, the operating room must be maintained at a minimum positive pressure differential of plus 0.01 inches water gauge relative to adjacent areas, including: Corridors, anterooms, scrub areas and nursing stations.

Here’s how the pressure cascade typically works:

The Operating Room is positively pressurized compared to corridors and adjacent support spaces. Sterile storage rooms are also positively pressurized to protect clean supplies. In contrast, soiled utility rooms or decontamination areas are kept at a negative pressure to contain contaminants.

These pressure differentials are actively monitored using sensors and pressure gauges. If pressure drops below the required threshold, alarms are triggered to alert staff. This directional airflow ensures that airborne particles from dirtier areas cannot flow into sterile spaces—critical for infection control.

4. Temperature and Humidity Control

Operating room’s must maintain temperatures between 68-to-75-degree Fahrenheit (20 to 24 degree Celsius). Keep relative humidity between 20 to 60% to ensure patient safety, staff comfort, and infection control. Tight control prevents microbial growth (high humidity) or static electricity (low humidity). Use Building Management Systems (BMS) to ensure precise regulation per ASHRAE and FGI standards. System temperatures can be set lower depending on the specific requirements of the operating room or staff.

Recap and Final Thoughts

To summarize, a hospital operating room HVAC system isn’t just about heating and cooling—it’s a critical infection control tool. Let’s quickly review the four key takeaways:

  1. Infection Control: HVAC systems prevent surgical site infections using HEPA filtration and airflow control by requiring a minimum air change rate which is defined by ASHRAE 170, 2021.
  2. Airflow and Layout: A vertical laminar flow pattern with low wall returns protects the sterile field by continuously removing contaminants.
  3. Pressure Management: Maintaining a minimum positive pressure differential of plus 0.01-inch water gauge is vital to keep clean air in and contaminated air out.
  4. Temperature and Humidity Control: Maintaining precise temperature between 68-to-75-degree Fahrenheit (20 to 24 degree Celsius). Keeping humidity (20-to 60% RH) in hospital operating rooms is critical for patient safety, staff comfort, and infection control. These conditions, mandated by ASHRAE 170, 2021 and FGI Guidelines, prevent microbial growth, reduce static electricity risks, and ensure optimal surgical outcomes. Building Management Systems (BMS) with thermostats and hygrometers enable tight control. This is done using reheat coils, humidifiers, and dehumidifiers to maintain stability. This factor underscores the balance between environmental precision and energy efficiency in OR HVAC design

By understanding these core principles, you’ll have a strong foundation in the design of one of the important systems in a healthcare facility.

Understanding the Air Quality Index (AQI)

MEP Academy Instructor
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Understanding the Air Quality Index (AQI)

Ever wonder if the air you’re breathing today is actually safe? Whether you’re going for a jog, sending your kids outside, or just stepping out for errands—air quality matters more than you think. In this video, we’ll break down the Air Quality Index (AQI) in simple terms, show you how to instantly check your city’s air rating using free tools, and explain what those color codes really mean for your health—today and long-term. Plus, we’ll show you how to compare your air quality to other cities around the world. Let’s clear the air—literally.”

What is the Air Quality Index?

The AQI is a standardized, color-coded system used in the U.S. and globally to communicate how polluted the air is—and what that means for your health. Index values range from 0 to 500, broken into categories from “Good” to “Hazardous”—each associated with recommended actions to keep you safe.

AQI is calculated for five key pollutants regulated under the Clean Air Act, including:

  • Ground-level ozone
  • Particulate matter (PM2.5 and PM10)
  • Carbon monoxide
  • Sulfur dioxide
  • Nitrogen dioxide

The index translates complex air quality data into a simple numerical scale from 0 to 500, with higher values indicating worse air quality. Each range corresponds to a color-coded category that describes the level of health concern.

How to Look Up Your City’s AQI

The EPA and other agencies maintain databases to track air quality across the United States. To find your city’s AQI, follow these steps:

  1. Visit AirNow.gov: Go to www.airnow.gov. Enter your city, state, or ZIP code in the search bar on the homepage. The site will display the current AQI for your location, along with a forecast and details about specific pollutants.
  2. Access the EPA’s Air Quality Index Report: For more detailed or historical data, visit the EPA’s Air Quality Index Report. Select your state and city from the dropdown menus. Choose the year and pollutant(s) you want to review (e.g., ozone, PM2.5). The report will show daily or monthly AQI data, including trends and summaries.
  3. Use the AirNow Mobile App: Download the AirNow app (available for iOS and Android) for real-time AQI updates on the go. Enable location services or manually enter your city to get instant air quality information.
  4. Check Local Resources: Many state or local environmental agencies provide AQI data tailored to specific regions. Links to these resources are often available through AirNow.gov.

Comparing Global Air Quality with IQAir

For those interested in comparing air quality across countries or identifying cities with the cleanest or dirtiest air, IQAir’s World Air Quality platform is an excellent resource. IQAir aggregates real-time and historical air quality data from over 130 countries, using measurements from ground-based monitoring stations, satellites, and environmental agencies. The platform provides a global air quality map, city-specific AQI readings, and rankings of the world’s cleanest and most polluted cities.

For example, cities like Delhi, India, often rank among the most polluted due to high PM2.5 levels, while places like Helsinki, Finland, frequently appear among the cleanest. IQAir normalizes data to a unified AQI scale, making it easier to compare air quality globally, despite differences in local AQI systems. Users can search for specific cities, view pollutant breakdowns (e.g., PM2.5, ozone), and explore health recommendations tailored to current conditions.

Why AQI Matters: The Health Perspective

Clean air isn’t just pleasant—it’s vital: Particulate matter (PM₂.₅) can travel deep into your lungs and bloodstream, causing inflammation and more serious conditions like COPD, heart disease, and even cognitive issues. Elevated AQI worsens asthma, affects pregnancy outcomes, and contributes to millions of premature deaths each year (Wikipedia). Globally, polluted air reduces life expectancy—by 5 years in India and 2.6 years in China (MedTech Pulse).

How to Protect Yourself on Poor AQI Days

  1. Check daily AQI before heading out—both AirNow and IQAir apps offer alerts.
  2. Limit outdoor activity when AQI levels are unhealthy or worse.
  3. Use N95 masks and indoor HEPA air purifiers during wildfire seasons or high pollution days.
  4. Plan outdoor time smartly—AQI often peaks in afternoon hours due to ozone and morning rush-hour pollution (AirNow, Wikipedia).
  5. Advocate for cleaner air—support policies that reduce emissions from transport, energy, and industry.

How to Read the AQI

The AQI is divided into six categories, each associated with a color, a numerical range, and a description of the health implications. Below is a breakdown of the categories, based on information from AirNow.gov:

AQI RangeCategoryColorMeaning
0–50GoodGreenAir quality is satisfactory, with little to no health risk.
51–100ModerateYellowAir quality is acceptable, but sensitive groups may experience minor effects.
101–150Unhealthy for Sensitive GroupsOrangeSensitive groups (e.g., people with respiratory issues, children, elderly) may experience health effects. General public is less affected.
151–200UnhealthyRedEveryone may experience health effects; sensitive groups may face serious issues.
201–300Very UnhealthyPurpleHealth alert: everyone may experience serious health effects.
301–500HazardousMaroonEmergency conditions: the entire population is likely to be affected.

Each pollutant is measured separately, and the AQI reported for a specific location is typically based on the pollutant with the highest index value at that time. For example, if ozone levels yield an AQI of 120 and PM2.5 yields an AQI of 80, the reported AQI will be 120 (Unhealthy for Sensitive Groups).

What the AQI Values Mean for You

The AQI provides guidance on how to adjust your activities based on air quality:

  • Good (0–50): Safe for outdoor activities for all.
  • Moderate (51–100): Most people can continue normal activities, but sensitive groups (e.g., those with asthma) should monitor for symptoms.
  • Unhealthy for Sensitive Groups (101–150): Sensitive groups should reduce prolonged or heavy outdoor exertion.
  • Unhealthy (151–200): Everyone should reduce outdoor activities, especially sensitive groups.
  • Very Unhealthy (201–300): Avoid outdoor activities; sensitive groups should stay indoors.
  • Hazardous (301–500): Everyone should stay indoors and avoid physical exertion.

For real-time advice, check the “Air Quality and Health” section on AirNow.gov, which provides specific recommendations based on current AQI levels.

In Summary

The AQI makes air pollution data easy to understand—through colors, numbers, and health advice. Platforms like AirNow and IQAir provide real-time updates for local and global air quality. Monitoring AQI can help you make smarter daily health decisions, and reduce chronic risks tied to air pollution. Advocacy and awareness lead to healthier air—and longer lives.

Stay curious, stay alert, and breathe easier knowing you have the tools to assess the air around you.

How to Read a Psychrometric Chart

MEP Academy Instructor
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How to Read a Psychrometric Chart

Ever looked at a psychrometric chart and thought, ‘What is this crazy spider web of lines? You’re not alone. But today, we’re going to break it down simply—no fancy math, just real-world HVAC understanding. You’ll learn how to read a psychrometric chart and use it to solve a basic problem you might face on a job site or in a mechanical plan review.

https://youtu.be/-SbfdTXGjhM

What is a Psychrometric Chart?


A psychrometric chart is a graphical representation of the properties of air. It helps HVAC pros analyze air conditioning and ventilation processes. Think of it like a map of air behavior.

Here are the key components of the chart:

Dry Bulb Temperature Lines

The horizontal axis shows Dry Bulb Temperature — the air temperature is in degrees Fahrenheit. Moving to the right the air temperature gets warmer, while moving left the air temperature gets cooler.

Psychrometric Chart Dry Bulb Temperature Lines
Psychrometric Chart Dry Bulb Temperature Lines

Relative Humidity Lines

The vertical curved lines are Relative Humidity lines, from 0 to 100 percent. These curved lines show the amount of moisture in the air compared to how much it can hold at a given temperature. It’s expressed as a percentage. When the relative humidity is 100 percent, the air is fully saturated, meaning it can’t hold any more water vapor and condensation may occur. This 100 percent relative humidity condition also happens when the dry bulb and wet bulb temperatures are the same, which is why that point lies right on the saturation curve of the chart.

For example, if we follow the 70-degree dry bulb line toward the 70-degree wet bulb the relative humidity keeps increasing until we reach this curved line which indicates the air has reached 100 percent relative humidity and is fully saturated.

Humidity Ratio

The vertical axis on the right shows Humidity Ratio, or grains of moisture per pound of dry air. The vertical axis on the psychrometric chart represents the humidity ratio—the actual amount of water vapor in the air. It’s measured in pounds of moisture per pound of dry air. As you move up this axis, the air holds more moisture.

Dry Bulb. Wet Bulb and Relative Humidity Lines on a Psychrometric Chart
Dry Bulb. Wet Bulb and Relative Humidity Lines on a Psychrometric Chart

For example, let’s look at the 70 degrees Fahrenheit dry bulb temperature line. As you move along that line and pass each increasing relative humidity curve—from 20 percent, to 40 percent, to 60 percent, and so on—the humidity ratio increases. That means there’s more water vapor in each pound of air.

When you reach the point where the dry bulb and wet bulb temperatures are both 70 degrees Fahrenheit, the air is fully saturated at 100 percent relative humidity. At that point, the humidity ratio is at its maximum for 70 degrees Fahrenheit air—about 110 grains of moisture per pound of dry air. That point lies right on the saturation curve.

Saturation Line

The curved upper boundary is the Saturation Curve — that’s 100 percent relative humidity. This outer curved boundary is called the saturation curve. It represents 100 percent relative humidity—air that is fully saturated with moisture. Along this curve, the dry bulb temperature and wet bulb temperature are equal. At any point on the saturation curve, the air cannot hold any more water vapor without condensation occurring

Wet Bulb and Dew Point Lines

Diagonal lines show Wet Bulb Temperature, Enthalpy (total heat energy), and Dew Point. The diagonal lines that slope upward to the left are wet bulb temperature lines. Wet bulb temperature reflects the lowest temperature air can reach through evaporation. On the 70 degrees Fahrenheit dry bulb line, as the wet bulb temperature increases—from, say, 55 to 65 degrees Fahrenheit —the humidity ratio also increases, meaning there’s more moisture in the air. At the same time, the relative humidity rises. When the wet bulb temperature reaches 70 degrees Fahrenheit —equal to the dry bulb—the air is fully saturated at 100 percent relative humidity and lies right on the saturation curve.

Why It Matters in HVAC – Real Use Cases


In HVAC, we use the chart to: Size dehumidification or humidification equipment. Analyze cooling coil performance. Control air mixing and ventilation and troubleshoot comfort complaints.

For example, let’s say your client is complaining about it feeling ‘muggy’ in their office—even though the thermostat reads 72 degrees Fahrenheit. The psychrometric chart can help you figure out if the humidity is the real culprit.


Let’s walk through a simple HVAC scenario.

PROBLEM: You’re conditioning air in a commercial office building. Outdoor air is coming in at 95 degrees Fahrenheit dry bulb and 60 percent relative humidity. You need to condition it to a comfortable indoor design condition of 75°F dry bulb and 50 percent relative humidity.

Air Conditions Plotted on a Psychrometric Chart
Air Conditions Plotted on a Psychrometric Chart

Step 1: Plot the Outdoor Air


This is your starting point. Use the dry bulb and move up to the 60 percent relative humidity curve to find the outdoor air condition.

Step 2: Plot the Desired Indoor Air


This is your target condition—comfortable for most people.

Step 3: Draw a Straight Line Between These Points


This represents the path air must take through cooling and dehumidification.

Step 4: Analyze What Happens Along the Line


As air moves across this line, it cools down and loses moisture. The cooling coil removes sensible heat and latent heat (humidity).

Step 5: Estimate How Much Water Is Removed


At 95 degrees Fahrenheit and 60 percent relative humidity, the humidity ratio is about 120 grains per pound.
At 75 degrees Fahrenheit and 50 percent relative humidity, it’s about 65 grains per pound.
So the cooling coil removes 55 grains of moisture per pound of dry air.

This is a simple explanation of how the psychrometric chart is used to solve problems and determine what happens to the air at various conditions.

Step 6: Total System Load (Optional Advanced)


“If you know the airflow rate—say 2,000 CFM—you can estimate total moisture removed per hour using formulas. But for now, just know this: The chart tells you how much cooling and dehumidification your system needs to achieve comfort.”

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