There are a bunch of fundamental issues that work together as a system for a home to be comfortable and durable. The Air Conditioning Contractors of America (ACCA) has distilled a massive amount of information into a series of manuals and standards. Most of them are very familiar (or should be) to HVAC contractors and engineers. Although the concepts are similar, every house is different in one way or another – a Manual J analysis of one house is not the same as the Manual J analysis of another. That is like a drive-by blower door test: “I did a blower door test for a house that looked like that yesterday, so this one must be the same!”

When houses were . . . just built and a large fireplace was the primary comfort device, there was no air conditioning, only rudimentary insulation and house wraps, and house construction was air-leaky enough for the structure to wet and dry naturally. Over the years, the technologies of comfort and durability have improved, and it is important that HVAC contractors understand how all those systems work together.

The manuals of the ACCA System Design Process are:

• Manual RS – System Concept
• Manual J – Room by room load calculation
• Manual S – Equipment selection
• Manual D – Duct sizing and system design
• Manual T – Air distribution and terminal selection
• Manual B – Adjust, Test Balance (Residential Duct Diagnostics and Repair)
• Standard 4 – Maintenance of Residential HVAC Systems
• Standard 5/QI – HVAC Quality Installation Specification

There are also a few less familiar – but none-the-less useful manuals and standards:

• Manual H – Heat Pump Systems Principles and Applications
• Manual P – Psychrometrics Theory and Applications
• Manual LLH – HVAC System Design for Low Load Homes

All eminently useful information, although the glaring missing link for me is ventilation system design, installation, balancing, and testing. The ‘V’ in HVAC is all too often a by-the-way remark. There is information on how ventilation impacts the heating and cooling loads but nothing on how the heating and cooling loads might impact ventilation.

The Home Ventilating Institute (HVI) has test procedures for verifying the performance of ventilation products for air flow, sound, and static relief vents and termination fittings. They used to have an installation manual (929) for Heat Recovery Ventilators. Because mechanical ventilation in low load homes is so vital and because there has been a rush to install a variety of balanced ventilation approaches, I have begun to renew the 929 manual and expand it beyond heat recovery ventilators to other balanced ventilation systems with a working title of Manual BV. If these systems are not designed, installed, commissioned, and maintained correctly they can be harmful to both the home and the occupants – and a waste of money! So please contact me and let me know your thoughts about balanced ventilation.