The HVAC technician is burdened with so many layers of laws, standards, regulations, and instructions it is bewildering. I figured I'd start a thread just to get some dialogue going:
In a State where you have building codes, those codes are the LAW. They are not suggestions or Best Practices. They are what you will be held to in a court of law should there be a loss with damages/ injuries. Now, a municipal building official is a Code Enforcer--not a Code Legislator (I'll wait for the laughter to subside). There is a legal mechanism to change local codes. Once the State has adopted a code, the local municipalities may or may not be allowed to accept it depending upon your State laws. For instance, the Statutes in Pa. allow municipalities to "opt out" of the Pa Uniform Building Code, which is essentially the 2009 ICC code suite. Therefore, when you work in each of the various 1,347 or so jurisdictions within the Commonwealth, you need to know if they adopted the Pa UBC/ IRC or kept the old BOCA codes. Regardless of what an inspector tells you, you are held to that code that was voted into law. He legally does not have the power to willy nilly change the code to suite his purposes. In order to change a local code (ordinance), you must submit the request to the governing body with substantial documentation on why this change is relevant and necessary, what the drawbacks are, economic burden, inspection and enforcement ramifications, etc. Once the Council has voted to proceed, you need three public hearings so stakeholders and the public can comment. If adopted, then and only then does it become an enforceable law.
Now, within that code are references to various other codes, standards, regulations, etc. By Statute, you are held to those standards the same and the full body of the code. For example: You go to replace an oil fired boiler with a gas fired one. Do you have any obligation to inspect or reline the chimney and if so by what authority? The IRC says for gas appliances, refer to NFPA 211 for what constitutes an acceptable masonry chimney. Now, the IRC details in Ch 10 how to build a masonry chimney and fireplace and that is not as restrictive as 211. So, which do you refer to? 211. It is specified in G2427.5.2 specifically. Moreover, it is also almost universally referred to in all installation manuals. So, what does 211 say? Well, that's a whole week long inspection cert. course but suffice it to say no existing masonry heater flue can pass a Level II inspection per Ch14 of NFPA 211 without a listed liner. So, you will have to reline.
What about an oil fired boiler installation? Well, the IRC refers you to NFPA 211 for the chimney, NFPA 31 for the general oil burner requirements and ASME CSD-1 for the boiler installation.
What about using listed factory built chimney or venting? The IRC simply states to refer to the listed instructions of that vent mfr. What if the listing calls for a clearances less than that typically stated in the code? Those clearances in the code are intended for unlisted appliances or when the listed instructions cannot be located. However, if a mfr. has tested and listed their product at a reduced clearance, then you may go with the listed spec.. Listings trump codes. Codes are general rules for the absence of engineered, tested, listed appliances and products.
That ought to stir some discussion. Enjoy!