Tag Archives: inspection

If all else fails, read the instructions

Buildings have always been changing, new material, new techniques and improved environments, that are slowly evolving to meet our needs.  In the past 10 years, the push to reduce greenhouse gases has accelerated this rate of change. In BC, the LEED standards mandated by municipalities, and the recently adopted ASHRAE 90.1-2010, are bringing some of the biggest changes in construction since the invention of Air Conditioning or the Elevator.  Most of these changes have also increased the complexity of the structure, and with any complex system, comes the increased probability of failure. Whistler

Take for example, this major high end hotel in Whistler. In the first two years, the owners of this property paid out over $100,000 in repairs because of problems with the mechanical system, that was not properly commissioned.  I was called to this site, to look at an issue with a make-up air unit ( MUA ) which was locking out on flame failure. On inspection, I noticed air blowing out of a sealed combustion chamber when the supply fan was on. This air pressure, was interfering with the burner ignition and causing the lock out. If the unit was 20 years old, this kind of issue can be expected, but this unit was only two years old. When I looked at the heat exchanger, the top part looked fairly new, while the bottom was a very dark colour. The duct work that was attached to this unit, looked normal and large enough to do the job.  However, how it had been connected, was a problem. The air flow over the heat exchanger was not even, it was creating a dead space over the bottom section of the heat exchanger. This difference, created thermal stress that warped the heat exchanger, just enough, to bend the tubes and open the seams. The manufacturer installation manual, did, provide proper instruction for the duct connection and, detailed the need for even air flow.  Although, due to how it was connected, it is highly unlikely the installer ever read the instruction. And so, I say thus, “When all else fails, read the instructions!”

 

Eng Air Make Up Air Unit
Eng Air Make Up Air Unit

The MUA, is used to pressurize the hallways and supply ventilation air to the building with outdoor air. Gas heating is used to warm the air in the winter and a chilled water coil is used for cooling the air in summer. A fairly common configuration for this type of building, but, there was also something unusual about how the chilled water was piped in. The Mechanical engineer, wanted to improve the efficiency, and use the cooling coil in the MUA, as an economizer, to cool the chilled water supply, when conditions allowed. This would reduce compressor operation and save energy. The design used a 3 way valve, to bypass the chiller barrel, and send the water to the MUA for cooling, instead of flowing to the chiller for mechanical cooling. When the economizer could not be unused, the compressor would cool the water and then flow to the MUA if the air required cooling. It would have worked too except for one little issue.

The mechanical drawing showed a 3 way valve, or at least that is what it tried to show. The symbol used for the valve on the drawing was a little unusual and was not very clear. The scale on the icon, may have been wrong when it printed and may have looked normal on a screen, but when printed, it did not come out right. There are a lot of little details in 2 dimensional mechanical drawings, and some can be confusing. I was told the plumber thought it was a thermometer and not a 3 way valve, so he  installed a tee instead, with a thermometer next to it. The construction plumber has no expertise in a Chilled water design, their skill is running piping. This little mistake, eventually resulted in a failed compressor, in the first 2 years, on a large chiller and, after the warranty and, long after the contractors hold backs were paid.

So why did two major pieces of equipment fail within two years?

Did someone forget to test the equipment? Did anyone inspect the workmanship? Who should pay for it? This is when the litigation phase of construction starts.

Had a Commissioning Authority been included on the design team, these problems would have been detected.

Out of site, out of mind

When inspecting a building after it has been constructed, it is very difficult to identify all the issues. A lot of details get buried into the building and not everyone on the site is concerned with the quality of the construction. If the expectation on quality, is not clearly defined in the beginning of a project in the pre-design phase, tradesmen, contractors or even design professionals can be motivated to hide details that might have a negative result.

Infrared Image of duct work
Infrared Image of duct work

 

An infrared camera is one tool we use reveal some of these hidden issue. It is a valuable tool in protecting your investment. In this picture, you can see the joint in the supply air duct work, that has been poorly sealed. This image told us to have a closer look at the duct work. The specifications for the duct work, were for all joints in the main ducts, to be sealed to Class A standards. In this case, the contractor used a lower grade sealant and is leaking more air than it should, a problem that is easily fixed. Because this issue was raised before the contractor received full payment, there was not even a hint of an argument and sealant was reapplied with a little more care and attention.

 

 

 

 

Above the duct work, the image shows a dark blue spot in the pre-cast concrete floor. Under normal light, the concrete appears normal and totally dry.  The cold spot, is water trapped inside the hollow cores of the pre-cast concrete. We drilled into the centre of this spot and drained about out 20 liters of water.

Image of water traped in pre-cast concrete
Infrared image of water leaking from pre-cast concrete slab

Eventually, we found that this was just one, of 50+ different locations throughout the building, where water had been trapped inside the building.

 

 

 

 

 

 

 

 

1-FLIR0331
Water leaking from Pre-cast Concrete Slab

 

 

 

 

 

 

 

 

 

Image of water draining from pre-cast concrete slab
Water collected from Pre-cast concrete core.

In many places, we were able to find the water and release it, and in most cases, control the release of water. We used a funnel and hose to channel the water to a container.

In other cases, the water release was a little more chaotic.

1-PCMC-Mens-Room 14-12-2013 5-54-56 PM

Click here for U Tube Clip of the Water Leak

When we investigated to find the source of the problem, we found several of the tradesmen on site were aware of the issue and brought it to the attention of the GC but never raised the issue with the design team.  The tradesmen on site, had been complaining about the water problem for several months and even offered solutions but their complaints were ignored. This issue was never raised at any of the job site meetings and the design team was never alerted to a problem.  Had the problem been dealt with it was first identified it would have been easily to resolve.  No action was taken until after the building was occupied and it became a serious and very expensive issue.