Thank you for that useful code reference. It might yield a solution to my situation.

I don’t think it takes much maneuvering to get to the code requiring it. Another example is the requirement for Manual D but no mention of ZR. But wait, there is a reference in D saying zoning systems should be designed in accordance with ZR. So in my “non liar”, I mean “non lawyer” mind, ZR would be required by code via the reference. Same is true for installation of flex duct referring to ADC guidelines which is in lots of flex duct installation instructions.

But at the end of the day, I dont think relying on code enforcement will make any difference. It has to be market driven. Change will occur when the consumer demands better design. Sadly, these days, the consumer doesn’t demand it up front and gives it no thought until a failure that cost them money, money, inconvenience or makes a family member sick. As Emerson said, no one studies geology until the day after the earthquake.

One thing you said intrigues me: “… since installation instructions are a mandatory code requirement”. That is an interesting angle. Is there actually something in the code that requires them to follow manufacturer instructions? I don’t recall reading that point anywhere. A reference to that specific thing would be useful. I see multiple instances of not following manufacturer installation instructions in my impending system.

Danny G,

I quite agree with you regarding lack of HVAC knowledge among many code inspectors. The village in question contracts out for electrical and plumbing inspections but handles the rest on their own. ACCA attempts to provide a solution for this by providing questionnaires for code inspectors to measure compliance but few seem to be aware of this resource. Doubtless the inspectors would cite a lack of time and manpower for real HVAC submittal evaluation.

https://www.acca.org/viewdocument/hvac-brochures-for-code-officials

Regarding duct design, I have a notion for how they could simplify system evaluation: static pressure measurements. Check total external static pressure compared to equipment ratings. Anything substantially outside of equipment design specification means that the installation does not conform to code. The majority of the time, it will be due to undersized ducts. For my system there is absolutely no design allowance for the optional media filter. I requested a friction rate worksheet from the HVAC contractor and their response was that they do not share their design details. They went on to explain how the ducting was properly sized for a .08 friction rate. At that point, it became obvious that they only use their Wrightsoft package to generate a local code required Manual J and duct design drawing that is not reality based and totally ignore the duct design capabilities of the software. One cannot share design details that were never created. As a result, I also hold the HVAC contractor responsible for what, in my opinion, is negligent work in violation of code since they are obviously not following ACCA or any other recognized rigorous design standard. I am unfamiliar with ASHRAE standards but seriously doubt my as yet uncompleted system would meet their standards either.

The builder shares responsibility here for enabling bad practices. I suspect that economics also come into play here. The builder received my protests as my wanting custom installation and refused to recognize my code objections because “they have built houses for years without major HVAC warranty claims” and “it passes code inspection”. Unfortunately, since I am not directly in the trade I am not given standing in the builder’s eye’s. My dad was in the trade and was trained in balancing too. I was exposed to much of Hank R’s knowledge that way so I actually do understand how badly this HVAC job is being executed.

Perhaps part of the plan b solution is inverters which modulate frequency from the actual building load imposed on the evaporator coil using temperature or pressure inducer employing refrigerant/temp as a surrogate. That might address the oversizing issue. But the duct design is still an unresolved issue.

Requiring independent review of HVAC design submittals with post installation inspection seems to be the only way to address this as someone else noted earlier.

Coming up with a plan B to deal with this mess is certainly challenging!

Specified Carrier 59SC5B 80,000 BTUh with 2 ton A/C when my own MJ8 shows only need 60,000 BTUh with 1.5 ton A/C. In model of this house at part load full sun 82 degree day A/C short cycles 8 minutes with no dehumidification 56.5 RH 55.4 DP. Above full load full sun 97 day runs short cycles 10 minutes with minimal dehumidification 60.3 RH 58.4 DP in low humidity Chicago June weather.

Duct work appears to be sized at 760 CFM design airflow with fixed .07 friction rate instead of actual CFM and calculated friction rate. In model return air is overly restricted with insufficient intakes and strangling the furnace on A/C with return duct 0.6 iwc so TESP estimated 1.1 to 1.5 iwc. A/C fan set about 1600 CFM! Heating CFM set such that high limit trip may occur with overall excessive static pressure.

I reviewed 4 MJ8 reports on 4 different builds of this same house with slightly different variations of most of the same errors which makes no sense. It screams careless at the very least.

Can you say code violations?

“For permitting, inspections, certificate of compliance or certificate of occupancy, verification of Calculations for HVAC Systems – ACCA Manual D, ACCA Manual J nor ACCA Manual S calculation submittals and review shall not be required”
Section 312 NC Mechanical Code

Problem Solved!