Keep Your Balance

Keep your balance!  When you're roller skating you know the importance of that statement.  Lose it and it's gonna hurt. 

In a commercial building if we lose our balance it's going to hurt, too.  But the balance we're talking about is not the same as when we're skating and the hurt is different, too.  In this case the balance has to do with the air quantities that flow through the air conditioning system and into and out of the building.  An imbalance in these air flows can create serious problems. 

Most often comfort issues such as hot and cold areas in the building are the trigger for investigating the air flow balance.  Humidity issues are also closely associated with balance, but the connection between the two is frequently missed.  Energy consumption is also another area that is connected with balance, but not often recognized.  (The cost can be significant if proper balance of air flows is not maintained and that hurts your bottom line!)  

In a commercial building air is exhausted from the building for many reasons.  Thankfully, restroom exhaust is mandatory.  Additional air is exhausted from buildings for many other reasons, such as kitchen exhaust or dirty linen closets.  In many cases the volume is very large.  Air to make up or replace this exhausted air must come from somewhere. 

Make up air systems are one way it is replaced.  These are dedicated to introducing outside air into the building.  In other cases make up air is drawn in through openings on roof top package air conditioners.  These openings are composed of a rain hood and damper to regulate the air flow to a measured volume.  These systems can be active; that is, responding to controls that will regulate the amount of air being allowed or brought in, or passive (the majority are), that is fixed, the volume of air does not change. 

Pressure imbalances (loss of balance in the exhaust and make up air systems) can - and do - cause serious problems.

Changes to the air conditioning system often result in air flow balance problems. 

Equipment is simply replaced, total air flow is not tested.  Make up air volume is not measured.   Building pressure is not measured.  It is assumed that because the same "size" unit was used, the air flow will be the same.  While overall cooling or heating capacity might be close, the blower capacity (the volume of air that the blower can move against a given pressure) differs from manufacturer to manufacturer, even between models from the same manufacturer.  Exhaust fans are often replaced with the same assumption being made. Often equipment is repaired, motors and pulleys replaced, with no thought given to what these changes will do to the air balance.  If the air volume changes, the balance is lost. 

For example:   An exhaust fan is replaced - it is a similar model, so no thought is given to checking the actual air volume being exhausted by the new fan which is exhausting a slightly higher volume of air than the old one. This results in the building pressure being slightly lower than the outside pressure (negative), unconditioned and unfiltered air is drawn in through any (and every) pathway available.   Humidity problems result from the additional moisture load.   Cooling or heating capacity is exceeded with the additional load.  Issues with gas fired equipment result.  Back drafting of gas fired equipment creates a fire hazard as well as a carbon monoxide threat.   As air is drawn down the flue pipe by the negative pressure within the building, flue gases are introduced into the occupied space  -  instead of being vented to the outside, now they are exiting inside the building.  If carbon monoxide is present (and only with perfect combustion is it not found) the results can be fatal.   Flame "roll out" caused by this condition results in equipment damage and fire.   As the name suggests, the flame "rolls out" of the equipment and can set fire to anything combustible.  Commercial kitchens have many pieces of gas fired equipment which are vulnerable to this condition.  Wiring and even gas valves, will melt down on equipment experiencing this problem. 

Count the number of exhaust fans on your building. 

• How many have been replaced in the last five years?
• How many have been repaired?
  
• How many have been tested for proper air flow? 
  

Make up air systems can fail or be altered resulting in very similar consequences. Replacement or repair of any equipment that is moving air into or out of the building can cause problems.  Unless the air flow volume is tested and verified as being correct, it's only a guess if it is going to work properly.  Not to be overlook is the air distribution system within the building, the duct work.   Is the air getting where it needs to go?  Air being supplied by the air conditioning system is distributed to individual areas of the building.  Changes to the equipment or duct system can alter the volume and distribution of this air.  For example, changing the style of grills in a renovation, can greatly effect the air volume. Cold or hot rooms, drafts, noisy supply grilles can all be associated with a loss of balance in the system.  Even equipment failures, such as compressor failures have resulted from air flow problems. Losing your balance is serious.  But it is seldom recognized as the source of seeming unrelated problems.

Specialized test instruments allow us to measure not only the volume, but the speed that air is moving in your air distribution system.   Sensitive meters allow us to detect pressure imbalances that can create serious problems within your building.  With this equipment and the necessary experience we can help you regain your balance!

Air Express Air Conditioning Inc.

Advanced Building Diagnostics