I’m not actually surprised that I failed the first inspection of the ventilation system. It makes sense that I would do some things incorrectly or at least not up to code. In this case I substituted lightweight zip ties over the approved tape to connect flex duct to the pipe. I needed to use a more heavy duty code approved band. The inspector recommended the stainless steel ring clamps which I used for some of the connections and so I’m getting more of them and redoing all the connections made with the zip ties. Tape, then ring clamp, then I should tape instead of zip tie the insulation over the connection.
The other problem I have is that I had the piping too convoluted and too close to the top of the ERV. Not enough room for maintenance for the unit. It is very tight with the unit in the space. Because the vents are on each side of the unit, it is more difficult to fit the piping in the space I created for the unit. This piping won’t do.
Three intertwining flex ducts
So I moved the ERV closer to the middle of the attic area and placed the pipes along one side of the ERV instead of over it. The inspector suggested I use duct pipe elbows to avoid having to make 180 degree turns with the flex duct. So I am adding 8″ elbows to the outside air supply and exhaust.
Supply and exhaust with elbows
The pipe has just enough room now to lay flat next to the ERV instead of over it. I have to change the pipe supports from the perforated metal strips to a wider mesh banding that won’t work holes in the insulation covering too.
New pipe layout
Unfortunately there is much less room to get around the attic area now. But hopefully enough for the installation to be approved.
The inspector also asked for the design documents. Luckily all of those are prepared for the LEED documentation so I sent these two files:
I hope they are adequate for the professional level of duct design and ventilation requirements that are expected for this type of system.
The inspector said since the unit and ducting are accessible we could progress towards getting the drywall finished before calling him back for another HVAC inspection. So we are close, but not yet approved.