Top 5 A/C Code Requirements not Enforced

  This list does not represent the entire code, or even all municipalities.  Everyone knows those towns that will hit you on every piece of the local code requirements, word for word from the text.  But, don't be surprised when code officials, both building and mechanical inspectors, start failing permit inspections for these previously rarely enforced portions of the code!  Are you going to wait until enforcement, or lead the industry in doing what the minimum is required by law?

1.  Duct Testing

  Although this has been enforced to some degree throughout MA and RI, the code is about to become a whole lot more stringent.  Gone will be the days of installing your duct systems within the building envelope to avoid pressure testing your ducts, better known as the leakage to outdoors test.  The only enforced standard, based on the 2012 International Energy Conservation Code (IECC), will be a total leakage test.  New duct systems must be pressure tested to 25 pa (.10"w.c.) and leak no more than 4 CFM per 100 square feet the unit services (Total Leakage/Sq.Ft = <4%).  To go from zero enforcement to the most stringent code internationally will be quite the wake up call for all of us tin-knockers!

System Design starts with a Load Calc!

2.  Equipment Selection

  ACCA's Manual S, Residential Equipment Selection, has recently been revised from the original published in 1995.  These updates include allowances for variable speed equipment.  I recommend you understand the sizing limits imposed in this manual as the 2012 International Residential Code requires proper sizing in the design process.  Some manufacturers make this process easy for you electronically, but most do not and some basic math will be required!  Equipment selection not only takes into account maximum and minimum limits to sizing, but also requires you re-rate your equipment based on the airflow and design conditions of your home.

3.  Condensate Overflow Switches

  This one sounds so simple, how could it not be enforced?  Well, this code requirement applies to all A/C, Heat Pumps, and condensing furnaces.  For conventional equipment, this overflow switch is typically installed on the overflow/secondary pan and stops possible damage to ceilings and floors.  What most do not realize is that this applies to Ductless, Mini-split systems as well. The switch must be much smaller than for conventional equipment and this cost can add up per indoor unit!

4.  Locking Refrigerant Caps

  Another "no-brainer" here.  This code requirement was without a doubt written blood, like most laws.  Unfortunately, every year there is a national story of some unexpected child that loses their life attempting to "huff" refrigerant.  I do not need to get into the particulars here, just start using them if you have not already.  This is one that I would promote manufacturers just institute on their own, it is an International Residential Code requirement!

5.  Line set Insulation

  In order to meet the minimum code for insulation on your line sets, they need a minimum R-3 value.  This should be clearly marked and listed by the manufacturer.  This seems simple but most of the industry uses untested, unmarked line sets that have no UV ratings.  Spend the extra few dollars, particularly for heat pumps, as this will go a long way with regards to efficiency.  Plus, it is required by code and not worth finding this out and re-installing a split system - that is a profit killer!

     There are many more code requirements that any HVAC Contractor should already know.  This list tends to be the least enforced in most areas.  Just because the speed limit is not actively being enforced does not mean you can safely travel at twice the speed, does it?

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Comment by Eric Kjelshus on June 16, 2014 at 6:30am

We just did comm job 50 sf per ton 100% outside air,  res very tight home with R- 20 wall and R-60 attic R-10 windows casement 1100 sf per ton.   Use better soft ware

Comment by Bob Blanchette on June 16, 2014 at 4:37am

Man J is too easy to fudge by changing input values. Is it a coincidence that most come out to about 500sqft per ton regardless of location and age of home?

Comment by Eric Kjelshus on June 9, 2014 at 2:51pm

I was teaching a class to high school kids  and I saw a " huffier"  with R-12  and sliver paint.   Most just steal the brass off the caps and make ear lobe hangers off the caps.    

Comment by Matt Giudice on June 9, 2014 at 2:46pm

Regarding number 1. Duct Testing... I believe the 2012 IECC still provides an exception to testing for duct leakage if the ducts and air handler are located entirely within the building envelope.  IECC residential provision R403.2.2 has an exception at the end after the duct tightness testing requirements:

"Exception: The total leakage test is not required for ducts and air handlers located entirely within the building thermal envelope."

It is true that duct leakage testing to the outside is no longer allowed as a compliance option in the model code, so maybe you are talking about situations where only part of the duct system is installed within the building envelope.

Some states (Iowa, for example) have adopted the 2012 IECC, but have made an amendment to that section in order to allow a testing option for duct leakage to the outside.

Comment by John Proctor on June 9, 2014 at 12:35pm

Christopher: I have been exposed to the statement that children die every year from huffing refrigerant. I would like to see reports that actually document specific incidents.

Comment by Greg Labbe on June 9, 2014 at 11:17am

She makes it look so easy, like Manual J is child's play!  ;-)

Comment by Eric Kjelshus on June 6, 2014 at 8:50am

Missing duct insulation now out side the building is now R-8  most I see just R-4.  

Locking caps on the outside is a pain - the lock can rot/rust/stick. then can not get off easy.  I have taken hack saw to take them off.  

Comment by Glen Gallo on June 6, 2014 at 6:57am

what about 12 inches clear for the condenser which I almost never see especially in production homes

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