2019 AHR Expo

Just returned from attending the Air Conditioning, Heating, and Refrigeration Expo held in Atlanta Georgia.  Some of the biggest names in the HVAC industry, such as Carrier, Trane, and York, were in attendance.  Along with cooling and heating equipment, those manufacturers that make specialty items such as boilers, compressors, piping, controls, motors and refrigerants were also in attendance.  Visitors, as well as vendors, came from all over the world to see new product lines as well as to showcase their products.  The trend, as has been the case for several years now, is to make machines more energy efficient.  Incorporating electronics to measure different parameters such as temperature and pressure, is now routinely done.  Depending on the type of equipment, manufacturers are also offering options on how the equipment is monitored.  Some owners prefer to let their on-site personnel keep up with the operation of their equipment while others are connected by internet to a servicing agency.

No matter how efficient or how well built a machine is, it will eventually fail.  Hopefully, when it does, there won’t be any property damage or personal injury.  But if there is,  the information collected during the Expo on various products will be invaluable in helping to determine the cause of failure and subsequent damage.  More specifically, the literature can be used to help identify a machine by model number, determine the pressure limitations, or establish the power requirements.

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Pumps and Glycol Solutions

Just completed two webinars; one on the use of glycols as heat transfer fluids and the other on retrofitting pumps in HVAC applications.  Both of these topics are related in that pumps are used to circulate fluids, including glycols, to transfer heat.  Typical applications for glycol use include the food and beverage industry, HVAC, and process chemical.  Pumps applications not only include the previously stated industries but also, utility; both electrical and water, petrochemical, and plastics, to name a few.  Insurance carriers that cover businesses in these industries need to be concerned because property damage as well as personal injury can occur when spills and pump failures occur.  Corrosion is a major problem in systems using carbon steel piping as a conduit for the transmission of the gylcol.  If not properly mixed and the correct inhibitors added, the glycol solution can be acidic and cause wear to occur in pipes and fittings resulting in leaks and spills, if not carefully monitored.  Similarly, the internal components of pumps can come under attack and fail as a result of the acidic conditions that could arise if the glycol solution is not properly mixed.  However, during such instances, insurance carriers are also considering the possibility of subrogating against a third party in order to recover their expenditures.  Potential defendants would include the company mixing and/or installing the glycol solution, the designer and installer of the piping system, and the selector and installer of the pump used in circulating the glycol.  It should be noted that the internal components of the pump can be selected based on compatibility of the fluid to be circulated.

Runaround Coil Heat Recovery

With all the talk about green house gases and oil dependency, energy efficiency and specifically, energy savings, is a top consideration these days.  One of the things that you don’t hear about too often is something called a “runaround” coil.  The system isn’t really limited to a coil but, instead describes a very simple  system for absorbing heat from one air stream and rejecting it to another.  Consider a large office building or hospital application where 100% outside air is conditioned, distributed to the individual spaces, and then completely exhausted.  A runaround system is nothing more than two heat transfer coils, one positioned in the inlet air stream ahead of the conditioning coils, and the other in the exhaust air stream.  The two coils are connected by piping in which water or a glycol solution is circulated by a centrifugal pump, hence the name “runaround”.  During the summer when outdoor air temperatures can reach into the 90s and 100s, the fluid in the runaround system absorbs heat from the outside air and in the process, cools it to a certain temperature.  The heat carried by the fluid is then circulated to the coil in the exhaust air stream where it is rejected to the air.  Heat rejection occurs because the exhaust air is at a temperature lower than that of  the fluid stream.  Significant energy savings occur when the cooling requirements of the building can be reduced.  For example, a building without a runaround system has a 100 ton load.  In order to meet the load, the cooling equipment has to cool outside air from 95 to 55 degrees.  Precooling of the outside air by 5 degrees (90 degrees) reduces the load on the cooling equipment to approximately 87 tons.  Dropping the cooling requirement by 13 tons can result in significant electrical energy cost savings.  Now, what happens if evaporative cooling is employed in the exhaust air stream? If an evaporative cooler is added upstream of the runaround coil, then the air stream can be cooled further resulting in an increased heat transfer rate from the fluid to the air stream, further reducing the cooling capacity requirements of the cooling equipment.   The use of a runaround coil is not a novel idea but one whose time is coming.

Air Conditioning in the Winter?

Whoever heard of air conditioning in the winter?  It’s cold outside and you need warm air, not cold to be comfortable, right? That certainly sounds reasonable.  After all, most people are using their furnaces at this time of  the year.  You might not be aware of it but, it is possible to create enough heat enough within an enclosure so as to require cooling instead of heating.  Most homes lose heat at a faster rate than can be replaced by supplemental sources (ovens, televisions, dryers, etc). As a result, some type of heating system has to be implemented in order to keep cold weather at bay.  However, in some office buildings, for example, the number of people and machines can easily produce enough heat to require space cooling in order to keep people comfortable.   Consider for example a 40 watt flourescent light bulb.  For each watt of power, the bulb produces 3.41 BTU/hr or 136.4 BTU/hr/bulb.  Most light fixtures are equipped with four bulbs. So, each fixture produces 545.6 BTU/hr. Imagine an office space equipped with 100 light fixtures. The total heat produced by all of  these fixtures is now at 54, 560 BTU/hr.  In terms of cooling, 1 ton of cooling is equal to 12,000 BTU/hr. The lights will require a cooling capacity of 4.5 tons. This doesn’t sound like  much but, when you start adding in other loads like people and computers, the heat output can be significant.

Buyer Beware!

Recently, we were called to investigate damage to a residential air conditioning unit. The allegation was that the unit was destroyed by fire.  Upon examining the unit, no evidence of fire was found.  That is, there was no evidence that any wiring or controls were burned and the compressor and condenser were both undamaged (as far as fire was concerned). However, during the examination of the unit, the compressor was found to have blown a terminal and caused its destruction. Most HVAC technicians will recognize this scenario. The possibility of lightning causing the damage was also explored and eliminated because there was no lightning in the area at the time of the compressor failure.  Instead of replacing the compressor, the homeowner had the entire unit replaced with a unit of greater capacity.  In doing so, the homeowner assumed that the insurance company would pay for the new installation which amounted to more than $8000.00.  Without a covered loss, the insurance company denied the homeowner’s claim leaving the homeowner to  absorb the entire cost of the new installation.   The lesson to be learned here is that you do not want to commit to a major purchase unless you can handle the expenditure if your insurer denies your claim. In this case, the cost to replace the compressor and recharge the unit would have been in the neighborhood of $1200.00 to $1500.00, which is significant lower than the new unit.

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