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Everyone makes mistakes.

The important thing is not to make the same mistake twice.

Each quarter we will take a moment to review a few details where encountered a learning experience of some sort.  The goal is not to point fingers or assign blame, but rather to create a space to learn from our collaborative experience, and offer resources so that if these issues ever occur in the future, you know what you are looking for, and how to *hopefully* ward of costly errors.

Rogue Roof Curbs
Roof curbs.jpg

The Issue:

In the picture on the right, the wrong curbs were sent to the job site by the manufacturer.  A detail we didn't notice until after the units were placed and after factory startup.  OUCH.

Take a look at the picture on the right, and note that the return sections are not lining up.  You can also see exposed gasket running down the center of the curb, sealing a whole lot of nothing.

The Fix:

This is a pricey fix.  Removing and redoing the curb isn't an option, so a curb adapter is most likely required. These can cost around $1500, not to mention the additional cost of the crane, and labor to do the fix. Up goes the job expense, down goes our profit in the job.


  • Triple check the curb submittal to make sure it matches the RTU submittal.  Vendors and manufacturers make big mistakes, especially when facing shortages like the current market.

  • Confirm the configuration of the supply and return when the curb is set, before the unit is set, and again when the unit is in place.  Make certain everything lines up correctly.

  • If you are not sure; stop and ask the question.   The delay in time for you to check the details is far cheaper than this fix when all is said and done. 


Check out our MCI STAT Course on Roof Curbs so this issue, is no longer an issue!

Rogue Roof Curb
Hole-y Moley
Hole in drain pan.jpg

The Issue:

This is one of those that makes you go "are you serious?!"

The electrical subcontractor drilled through this stainless steel drain pan... TWICE... on four different AAON units to run conduit for the fire alarm.  They also used standard MC (which will rust), instead of waterproof conduit ( a drain pan... made to catch water).

The Fix:

Undoubtedly a good deal of actual repair cost will get shifted back to the electrician who made this error. They will have to come back out to move this conduit, and we will need to seal the hole left in its place.  A welded patch is likely ideal, along with silicone reinforcement.  However it's important to note that once the stainless is compromised, any patch in the future will eventually leak.  There's a good chance that this will drive up warranty costs in the future.

Not to mention additional delays to the job, and added labor costs to fix it all.  Time is money!

Hole in drain pan 2.jpg


  • Just because they're supposed to be the experts hired to do the job, doesn't necessarily mean they know what they're doing.  Coordinate in advance with the electrical subcontractor on the job, and make sure that they know what they're doing as it relates to your scope on the job. 

  • This is a long shot, but try to keep an eye on their work.  Maybe we could catch this before they get through 4 units? Tough to say, but definitely a head-shaker.

Hole-y Moley
Gas Regulator Gripes
plumbing sub gas piping_edited.jpg

The Issue:

In the picture on the right, this gas regulator was installed backwards by the plumbing subcontractor.  The vent should be on the input side. 

The Fix & Takeaways Combo:

This isn't necessarily our issue, but since we do deal with natural gas piping and it affects our equipment, its important to know what to look for here.


How can you tell?  There's a couple of details to break down.  First, if you look verrrry closely at the left side of the regulator, you can see a tiny "IN" on the housing. That's right ladies and gentlemen... it literally says it on the valve. 

Beyond that, it's important to know how a gas pressure regulator works and you'll be able to notice these issues quickly because you understand the big picture. And guess what? There's a STAT for THAT.


Check out our MCI STAT Course on Natural Gas Piping for an excellent breakdown of how these valves work, and how they should be installed !

gas regulator slice.png
Gas Regulator_edited.jpg
Gas Regulator Gripes
Hepa Filter Hardship

The Issue:

This is a doozy without necessarily any advised "fix" because the reality is that we don't really know what went wrong.  When doing clean room certification for a local medical office building, 12 of 36 HEPA filters were tested and failed.  The inspection was then stopped, and it is assumed that the remaining filters will fail as well.  We are on the line to replace all of these filters at a very high cost.... but what went wrong?  Well, it could have been a number of things.  Let's discuss so that you might know what to look out for if you come across a similar situation.


  • The first rule when it comes to these filters starts when you receive them; please double check for any damage from shipping or transportation. If the box is damaged, note it and reach out to the manufacturer as a precaution.

  • Ensure that these filters are stored in the proper manner; that means out of the way from busy traffic and in a climate-controlled space. One possible failure for this filter is they sat in a connex for several months and faced extreme temperatures causing issues with the gel gasket.

  • Another important note is to inspect the filter and grille prior to installation. If you see any damage, document it with pictures and report it to your supervisor immediately. If the grille is damaged, then you will not get a proper seal and will need to be replaced.  There is no fixing it in the field. These filters come tested from the factory and will not be replaced under warranty if the proper precautions are not taken.

  • This is not a one-person job.  With how these filters work is you get one shot to install and get a good seal, if you don’t then it’s a $500 mistake per filter if you don’t get good adhesion and the proper seal. It takes a minimum of two people per filter to install.

  • Rubber gloves are required for installation and no contact with the filter’s media can occur, otherwise it voids the HEPA certification. The surface where the gel gasket goes to needs to be cleaned with acetone and free from dust. This is the most important part of the installation process. This is a common failure point for these filters, and where they fail in HEPA filter testing is around that gel gasket. The key is to take your time and ask questions if you are unsure.

  • The other lesson learned if you are going to have HEPA filter testing is to ensure you only install a couple and have them test those first prior to installing all of them this ensures that your method of installation is correct, especially when you have large quantities of these filters. It is also important to have spares, these filters lead times vary and if you have a failure then you need to have a few spares as it can take several weeks to get a replacement.

HEPA Filter.jpg
Hepa Filter Hardship
Multi-Story Misfortune

The Issue(s):

We’ve had a couple of installation issues revolving around terminal units. 


The first issue we had was with a fan box being installed upside down. The installer’s intent was to give themself the maximum clearance to the electrical cabinet, as we sometimes do with single duct units (VAVs).  Unlike VAVs the fan powered boxes must be installed with the top of the unit up in order to maintain service access to fan and motor. 


The second issue we came across was an exhaust air VAV installed backwards. The exhaust air boxes are all single duct VAVs. These units must be oriented so that the exhaust air hits the flow ring first. However, many engineers show these boxes on the plans oriented in the same manner as a typical supply VAV. This discrepancy between the drawings and the actual equipment function creates confusion in the field, and often results in the boxes being installed backwards. It also complicates the duct fabrication process, as the inlet of the box is often shown on the upstream side of the duct system, which is incorrect. 


In both cases we were able to identify the issues during a construction progress walk, which allowed us to correct the installation with limited impact to the job.

VAV Boxes.jpg


Get familiar with the installation of terminal units through our STAT course dedicated to proper install and common fails.

Multi-Story Misfortune

When you make a mistake there are only three things you should ever do about it: admit it, learn from it, and don't repeat it. 
Paul Bear Bryant

Have you come across a learning experience? 
Let us know. We may have educational resources that we can share to the benefit of all.

Thanks for submitting!

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