How do you fix a humidity problem?

Humidity, the 8th wonder of the world, is a tough nut to crack. Unlike sensible heat transfer, it’s very difficult to measure its movement into buildings through cracks, doorways, and other openings.

But, there are ways to combat these higher than expected humidity levels.

Here are 11 ways to decrease the relative humidity in your space. The answer could be one of these 11, or in many cases it’s a combination of a few. 

      1. Check and Reduce Airflow if Necessary 

        This is a great place to start because if your airflow is not in a good range, you will avoid future issues by correcting it now. We discussed this in our previous blog, but basically, the lower the discharge air temperature off the coil, the lower the space humidity will be. And when you reduce the airflow, the discharge air temperature will decrease. 

        So, step #1 would be to measure airflow, and if it is HIGHER than 400 cfm/ton, reduce it to the nominal rating. If that doesn’t help, lower it some more, but don’t go much lower than ~320 cfm/ton. 

        CAUTION #1: If you lower airflow below ~320 cfm/ton, you risk freezing the coil in standard A/C operation. Make sure you check filters consistently, because a plugged filter will freeze the coil faster at lower airflow speeds. 

        CAUTION #2: When you lower the discharge air temperature, you will lower the temperature of the ductwork and supply registers, which means they might sweat. 

        CAUTION #3: Lowering the airflow reduces your unit’s total capacity. If you can’t afford to be low on capacity during the heat of the summer, this might not be the right move. 

      2. Check economizer minimum position 

        Most rooftops and split systems are now being installed with an economizer for free cooling, but if it’s not set up properly it can cause humidity issues. If the thermostat fan mode is set to “on” instead of “auto”, and if your economizer minimum position is open, you might be bringing in HUMID air constantly. And if that air doesn’t have a very high (dry bulb) temperature, then you might not get a call for cooling to remove the excess humidity. 

        If local code requires fresh air for people, consider installing a CO2 sensor, and setting the economizer to be 100% CLOSED unless the CO2 calls for fresh air. 

      3. Add a VFD to stage airflow

        On units that have multiple cooling stages, this will help. When first stage of cooling is running and the supply fan is at full speed, the evaporator coil doesn’t remove as much moisture. If you install a VFD (Variable Frequency Drive) on the supply fan motor, and then operate the fan at 50% air flow on the first stage cooling call, you will lower the coil temperature and remove more moisture. You also will lower the capacity of the unit (at the half speed setting) and thus will run longer to satisfy, which will remove even more moisture. 

        CAUTION: Check the evaporator coil circuiting. If it is row split or intertwined split, you are good to go. But if you try to do this with a face split coil, you will probably freeze the coil at the lower airflow. 

      4. Auto-Fan control is your friend 

        We discussed this briefly in #2, but its worth further discussion. If the thermostat fan setting is set to “on”, then the unit will be bringing in outside air constantly, which could be humid air and might be causing the issue you are having. 

        The other problem with “on” fan, is after the cooling call goes away, all the moisture on the evaporator coil will evaporate back into the air stream and into the space. 

        Setting the thermostat or controller to “auto fan” control avoids these two issues. 

      5. Different setpoints 

        If you have multiple units serving the same space, you can set one unit at a 1 or 2 deg higher setpoint. For example: unit #1 set temp at 74, unit #2 set temp at 75. When you do this, the first unit runs full cooling before the other one comes on. If you don’t do this, each unit will cycle on/off on first stage during mild weather, and neither will run at full cooling. Which means the evaporator coils never get cold enough to maximize moisture removal. This is the same concept as adding a VFD (#3) or lowering your airflow (#1). 

      6. Raise the thermostat set temperature

        It’s probably worth your time to review our other blog, How to avoid a humidity problem. When you lower the space temperature setpoint, you will actually RAISE the space relative humidity. Yes, it’s counterintuitive, so in the best interest of time, check out our other blog.

      7. Check building pressure

        Are there exhaust fans removing a lot of air? If so, is there a makeup air unit making up that air and cooling it? (Like a DOAS unit). If the makeup air is coming in through louvers or through a standard rooftop, this could be the cause of the issues. 

        If there IS a make up air unit, make sure its running properly. If it’s running, but the building is still under a big negative, there is something still missing from the equation. 

      8. Check the ductwork

        Is all of the supply and return ductwork serving the same area? If the return ductwork is pulling air from another space (that is humid for some reason), that might be the issue. 

      9. Vapor barrier 

        Is there one? 

      10. Spot removal 

        Does the building have a piece of equipment generating steam or humidity in a concentrated spot? You might look into a hood and exhaust fan to remove it. Beware though, this might put you in a negative pressure situation (#7).

      11. Dehumidification units

        If every option has been exhausted, this is where you might end up. The only way to TRULY control humidity is by using a unit with a dehumidification circuit. If you are prepared, this feature can be built into packaged rooftop units during the manufacturing process. If you don’t have that luxury, then you might need to look at adding electric, steam, gas, or hot water reheat of some kind. This allows the unit to run in full cooling mode on a call for dehumidification, but then reheat the air so that you don’t OVERCOOL the space. 

Do you have a project that needs an extra set of eyes? If so, give us a call at (800) 322-9675 or shoot us an email at

How many tons of air conditioning is this DX or Chilled Water coil?

If you are measuring a Direct Expansion (DX) or Chilled Water coil in the field, or just quoting a replacement coil, you can quickly estimate its nominal tonnage based on the square footage of the FIN area of the coil. 

This is a useful “rule of thumb”, which will help ensure that you have all the information you need before leaving the site or getting off the phone with your customer.

It’s also a good double check to make sure you aren’t missing something major.

Since most evaporator coils are designed for a maximum face velocity of 500 fpm (to eliminate condensate blow-off), and nominal airflow is typically 400 cfm/ton for comfort cooling applications- here is the formula for determining nominal tonnage based on square footage of the fin area of the coil. 

(Ft^2 of fin area) x (500 fpm) / (400 cfm/ton) = Nominal Tonnage

For example-

If: Fin area of the coil is 58” x 20”

Then: Fin area = 58 x 20 / 144 = 8.0 ft^2

8.0 ft^2 x 500 / 400 = 10 Nominal Tons

To simplify the equation: (square feet of fin area x 1.25) = Nominal Tonnage 

This can be done in reverse as well:

(Nominal tonnage) x (400 cfm/ton) / (500 fpm) = approx. fin area in square feet

So, if you are about to go measure a 30 ton evaporator coil, you should expect to find a coil that has approximately 24 square feet of

fin area (30 / 1.25 = 24 ft^2).

Note: All of this ASSUMES 500 feet per minute and 400 cfm/ton airflow. 

Make up air units typically run at HALF of this airflow (~200 cfm/ton). And plenty of air units are designed for 300 fpm across the evaporator coil. 

The point is, these equations should only be used as a “rule of thumb” to double check or to estimate the nominal tonnage of the system. 

If the square footage is far off, then you might be dealing with a 100% outside air system, or a low discharge temperature application. 

Let us know if you would like us to meet you in the field to measure a replacement coil. We’d love to help!

What’s in a slogan

“Melts in your mouth, not in your hand”

“The few, the proud, the Marines”

“What happens in Vegas, stays in Vegas”

A close up of text on a white background

Description generated with very high confidenceThese are just a few memorable slogans that we all know. Why? They are catchy, short, and it allows us to connect with the brand.

Having a slogan produces many benefits and companies of all sizes can and should have one. A well-constructed slogan can really make a dramatic difference setting you apart from others in your industry. If you have a memorable and authoritative tagline this will certainly leave an impression in the minds of consumers.

The purpose of a slogan is to give information about key benefits of your product or service and what makes you different from your competitor. It makes people aware of what you are offering and how you are different from everyone else in the industry. Think of this as your “mini” elevator pitch, make it strong and highlight a benefit of your product or service. It will provide future customers with a picture of what you offer. Keep the message clear, include at least one benefit and no more than a few words, keep those words positive and upbeat. A brief catchy tagline goes a long way in branding and identifying your business. Slogans can generate publicity and attract attention to a product or service.

There is no denying that historically taglines and slogans have been memorable, pervasive and influential to consumers. As our world becomes more sophisticated and technology driven more and more companies are coming up with clever ways to capture the attention of consumers. Puns, nouns, adjectives and even made up words are just a few ways of capturing that audience. The future of slogans might even be determined by the words and phrases being used, especially when using Google to find a business. Take some time to think about a creative message for your slogan, you’ll be glad you did.

Here are some fun memorable slogans, do you recognize them?

  • “Where’s the Beef?”
  • “Just Do It!”
  • “You’re in Good Hands with Allstate”
  • “Taste the Rainbow”
  • “Got Milk?”
  • “I’ve fallen and I can’t get up”
  • “Clap on! Clap off!”
  • “He Likes it! Hey, Mikey!”

If you would like help creating a unique slogan give me a call and I can help you make your business slogan stand out from the rest.

How to avoid or fix a humidity problem

One of the problems that we run into during the summer months is “Our space humidity is too high”.

Or, “We would like to design our space temperature and humidity to be “68 degrees and 45% RH,” for example.

The purpose of this post is to help you quickly determine if standard unitary equipment will do the job, or if you will need a more customized solution (both of which we can help with).

In order to learn this subject, all you need is an open mind and a psychrometric chart. If you don’t have a psychrometric chart handy, don’t worry, we will show you all the info you need below.

Discussion #1

How to design for a specific space temperature and humidity requirement:

1. Choose the design space temperature and humidity requirement

2. Plot this point on a psychrometric chart

3. Draw a line straight to the left to determine the MAXIMUM discharge air temperature

4. Add reheat if necessary

5. Vapor barrier and other considerations may come into play depending on building construction and project requirements

The major point to note here is that standard air conditioning equipment is typically designed for a discharge temperature between 55-58 degF. So if the required discharge temperature is close to this, you can probably get away with unity equipment.

If, however, the required discharge temperature falls into the 40s or lower, you will need to look at a custom solution. Either way, ask your distributor or manufacturer’s rep to run an equipment selection to verify that you can achieve the necessary discharge temperature for your application.

Discussion #2

How to correct a space humidity issue:

1. Plot the current space temperature and humidity on a psychrometric chart

2. Plot the desired space temperature and humidity on a psychrometric chart

3. If you can draw a straight line to the right to achieve your desired set point, simply raise the space temperature set point

4. Vapor barrier and other considerations may come into play depending on building construction and project requirements

This is the very first step to take when diagnosing a humidity issue. It’s a common misconception that lowering the space temperature reduces the relative humidity. As you can see from the psychrometric chart, when you lower the dry bulb temperature, you actually RAISE the RELATIVE humidity.

If this doesn’t fix the problem let us know and we can help you find a solution that will work for your project. Many times an airflow or building envelope tweak can fix the issue.

Do you have a humidity problem we can help fix?

Are rooftops a commodity? Maybe.

Are rooftops a commodity?


But there is a lot to think about when replacing an existing unit, or doing a design/build job.

Is quick and easy access important? Maybe we should look at a unit with hinged and toolless access and a slide out blower.

Is comfort critical? Maybe we should look at more cooling stages and adding a VFD.

Is this a mission critical job where no downtime is important? Maybe we should add Fault Detection & diagnostics to give us early failure warning sign alerts.

Do we need to keep utilities on budget? We might want to look at a high efficiency unit, or adding a VFD.

Is ease of scheduling important? Then we might want to look at a control solution, which could require a special MODBUS, Bacnet or N2 board.

What are the existing controls? Maybe there is a proprietary control system that won’t communicate with a standard rooftop board.

Do we need cooling year round? There are lots of ways to do this- economizer, condenser fan cycle control, condenser fan speed control based on liquid pressure, condenser fan speed control based on liquid temperature. Which method is the best for the application? Maybe it’s a combination?

What city is the job in and what are the local energy and mechanical codes? Does code require an economizer? Should that economizer be dry bulb, enthalpy, or dual enthalpy?

How many stages of cooling does code require?

Does code require CO2 sensors or a smoke detector? Maybe two smoke detectors depending on the unit size?

If we have to meet ASHRAE 90.1-2010 we will need to add a VFD if the unit is 10 tons or larger.

Is there a humidity requirement? Might need to consider hot gas reheat. Or we might need to design to a 45 or 50 degF discharge temperature (grab your psychrometric chart first!).

Is it important to have replacement parts available quickly? Might need to make sure we select a unit supported by a distributor with a local stock of parts.

Is building pressure control important? Should we look at on/off power exhaust? Or modulating exhaust with a VFD and building static controller?

And…the list goes on.

Either way, this LONG list is the reason we ask so many questions when we get asked to price a rooftop unit.

We want to make sure we get the right unit on the job the first time.

What questions did we forget to address?

HOW-TO Access Your UPGnet Profile and Change A Password


“Can you reset my password?” is one of the most frequently asked questions I get from our dealers. With technology hacking these days, a strong password is vital to keeping information secure. But it can also be annoying when every website you use has different password requirements and different expirations. Most people take advantage of the browser password storage option. The big downside to that is you get used to using the storage option then when you need to remember your password, you can’t see what the password is, and you can’t remember it on your own.

Such is the case with many of our dealers and UPGnet has a set amount of time before they expire a user’s password and require a password change. That’s where I come in. As one of your UPGnet Administrators at cfm, I have easy access to go in and reset your password. However, this isn’t always the easiest or quickest option if for some reason I am unavailable. So here are a couple of easy steps to get you into your user profile so you can update your password and settings to get an email from UPGnet when your password is about to expire.

Step 1.

First log in by going to Once there, you will be asked to enter your username and password. Your username is all lower case and all one word (johnsmith). Enter your password and hit LOGIN.

Step 2.

Once logged in, you will see the screen below. Feel free to click the DO NOT SHOW THIS PAGE AGAIN link if you want it to take you straight to the homepage.

Click on the GO TO CENTERS button to head to the home screen.

Step 3.

Click on the ADMIN AND HELP CENTER link to the left.

Step 4.

Click the PROFILE button

Step 5.

You should now see a screen like the image below that gives you access to your profile. You will see all of your information such as phone, address, email etc.

About halfway down on the screen you will see a check box called * !PasswordExpEmail!. Check this box and click UPDATE PROFILE to ensure that a “Password Expiration” email goes to the email address in the user profile. usually sends an email reminder 2 weeks before your password is set to expire.

And lastly,

Step 6.

At the bottom of your profile screen you will see a spot where you can update your password. Please make note that you must know your old password to update a new password on

All passwords must include the following:

  • one uppercase letter
  • one lowercase letter
  • one number
  • one special character such as: !@#$%^&*

NOW YOU’RE ALL SET with step-by-step instructions on how to access your user profile and password. Please remember that if you ever need any assistance with, contact your cfm Marketing Team and we will always assist you.

Get In The Millennial State of Mind

Millennials are the digital generation, they’re smart, savvy and socially conscious and they make up the largest generation today, with estimated 79-80 million members. Why is this important to your business? The larger the population, the bigger the impact on culture, opportunities, behavior, trends and so much more. If they don’t fall within your businesses target audience they should because this generation will be valuable down the road.

These young adults are also some of the most educated individuals in US History with over a third earning a four-year degree or higher. This tech-savvy generation researches brands and services and do their homework when it comes to finding a brand, product or service. They look for companies who are authentic, honest and are upfront with pricing.

More and more millennials are purchasing homes and the rise of this generations home buying has been growing year over year. Last year was the largest increase of any age group over a previous year.

So how do you advertise to this progressive, fearless and tech savvy generation? It’s certain that they find most of their information about products and services through social media, online research and referrals from friends. This group has the highest use of the internet as the main source of gathering information so you need to be at the right place at the right time to capture their attention. Below are several key factors to consider when marketing to millennials.

  • Emphasize Digital Marketing

Make sure your website is up-to-date and mobile friendly, if not, they will pass you by. Have a social media presence on Facebook, Instagram and Twitter. Digital display and video ads that run across multiple devices (especially a mobile device). You can retarget them with your ads as they move along the internet. Millennials would rather watch a video or see a graphic ad than read text. Remember, this group has grown up with technology and this is the norm for them.

  • Appearance and Style

Show the difference between your product and service and your competitors; that way the “all of these look the same” mindset is gone. Talk to them about digital thermostats and how HVAC units are more digital than ever before. This will intrigue them and they will respect that you took the time to give them additional information even though they’ve done their research online prior to calling you. After all, this is the most tech savvy generation.

  • Referrals

Word of mouth is still the best type of lead and it holds true with this group since they are social media gurus. Reviews and recommendations on your social sites and other review sites is imperative if you want to be considered by a millennial. Ask for a reference from another millennial that you’ve done work for and use that to gain additional millennial customers.

If you want to take advantage of this generation and their buying power you’ll need to stay up-to-date on their trends and incorporate your marketing strategies and advertising tactics to attract and retain them.

Do you need help marketing to millennials? Give me a call today and I can help you construct a plan.

EER, IEER, SEER, IPLV, HSPF… What do all of these efficiency terms REALLY mean

EER, IEER, SEER, IPLV, HSPF… You have probably seen all of these terms before and never even thought of what the heck they stand for, or why you would care to look at one over the other. In order to look out for the best interest of the building owner, however, it is important that all of us in the industry can articulate the differences to our customers to ensure the proper equipment is selected.

With the Department of Energy changes on the horizon, I thought I would take the opportunity to dive into what all of these efficiency terms REALLY mean, and what impact they have on end-users and the environment.

EER – (Energy Efficiency Ratio)

This value shows efficiency when operating at peak load capacity (when you could fry an egg on the sidewalk). Although it is a good reference, it can be a misleading representation if you live in a part of the country with seasons.

Defined as “the ratio of the cooling capacity of the unit (in Btu per hour) to the power input (in Watts)” – This is calculated at 95/75 degrees DB/WB (AHRI Standard Rating Conditions).

IEER – (Integrated Energy Efficiency Ratio)

This value is more representative of the actual efficiency you will get out of your HVAC equipment. To calculate this value, efficiencies are reported at different loads (outdoor temperatures ranging from 65 to 95 degrees F) and then given weights to obtain an overall efficiency value. Surprisingly, the peak load efficiency only counts for 2 percent of the overall value! IEER is calculated as follows:

IEER = (0.02 * A) + (0.617 * B) + (0.238 * C) + (0.125 * D)

Where as:

A = EER at 100% net capacity at AHRI standard condition (95 deg F)

B = EER at 75% net capacity and reduced ambient (81.5 deg F)

C = EER at 50% net capacity and reduced ambient (68 deg F)

D = EER at 25% net capacity and reduced ambient (65 deg F)

SEER – (Seasonal Energy Efficiency Ratio)

Calculated very similar to IEER above, however, this is more common for residential equipment.

IPLV – (Integrated Part Load Value)

More geared towards Chillers, but still calculated the same way, and gives a standard for real-world efficiency comparison. The formula from AHRI is below:

IPLV = (0.01A) + (0.42B) + (0.45C) + (0.12D)


A = COP or EER @ 100% Load

B = COP or EER @ 75% Load

C = COP or EER @ 50% Load

D = COP or EER @ 25% Load

So, if you are designing for a space with somewhat constant internal loads that are independent of outdoor air temperature, EER is a good indicator. These types of applications come about from time to time in commercial and industrial spaces so it is important to make sure to use the correct basis for comparison.

However, in the much more likely scenario that you live in a place with varying outdoor air temperatures and internal loads, IEER and SEER will be your best bet!