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?