Ducting Plan for ERV
Sorry for the length of this, but I’m going crazy with the amount of available information on ventilation systems, and I’m hoping you would all be willing to help me out again on decision making for new house options (I took Akos advice to skip flash and batt and just go with R21 fiberglass cavity insulation on another post).
I realize that an ERV with dedicated ducts is best. The problem is the track/spec home builder I’m buying from only offers a few custom items. They will install a Trane ERV on one of the two Trane air handlers for $3,800. I don’t believe I can get their sub to do a standalone ERV system. Base price includes the code minimum exhaust only system with a bathroom exhaust fan on a timer. I guess these are my options:
1. Get the Trane (rebranded RenewAire I think) ERV. I realize this isn’t the most efficient design, but keep in mind I will have a variable speed ECM air handler. It also saves me the headache and time requirement of the other options, which is equally as important to me as the upfront cost.
2. Do nothing now, have just the exhaust only system, wait until I move in and test for CO2. Then at that time if needed do one of the following:
2a. Install standalone ERV (likely Panasonic intelli-balance) which will cost $1000 plus materials for ducts and bulkheads. Then take the timer off the exhaust fan.
2b. Install supply fan for balanced system in forced air return duct. Control based on either exhaust fan or air handler activation? I’m thinking have it turn on when heat/cool comes on so it is always treated, realizing that I will have an exhaust heavy system on shoulder seasons.
2c. Install supply fan for balanced system into open area, controlled by exhaust fan timer. My house is an open concept with an open stair at the end of the house that connects conditioned basement, first, and second floors without doors. I was thinking of dumping the outside air here if I go this route.
Assuming those are options, which would you recommend? Option 1 is quick and easy but pricey and not perfect. Options 2a-c may not even be needed if the exhaust only system works well enough, but that is a risk. They are then cheaper but either less efficient than option 1 (2b-c) or require almost as much money but extra time and retrofit effort (2a).
Thanks for taking the time as I assume it will be beneficial for lots of buyers in the mid-Atlantic area. Some of my specs for consideration:
Maryland – Zone 4A
2018 IRC/IECC design
Around 4,800 square feet not including conditioned basement.
Around 6,500 square feet including basement.
All electric, no combustion appliances
1 air handler for top floor (unit in closet, ducts in attic (sorry))
Bedrooms for the two kids, the wife and I upstairs.
1 air handler for main floor and basement
Apartment for the elderly in-laws on main floor.
Exhaust fan on timer is in buddy bathroom shared by kids with doors opening into each of their bedrooms (not hallway).
Thank you all again for the great content and advice
GBA Detail Library
A collection of one thousand construction details organized by climate and house part