Forced air register placement
I’ve read a fair bit about register placement but most of it seems to be relatively old (5 years or more) and I would love to hear an updates discussion (debate?) about the best practices today.
All of my registers are placed on exterior walls, generally under windows. They are all the “baseboard” style, which means the duct boot is installed in a floor cutout and a triangular metal register directs the air.
Being in a heating climate this was traditionally considered the best approach for comfort reasons. However, it also means that on the second floor the ductwork must be run inside an exterior wall with all the associated tradeoffs.
With our renovation project we will have the opportunity to move ductwork around and I would like to hear what the current thinking is on this. I’m also curious about using true wall registers instead of baseboard registers.
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Replies
Christopher,
I'm not an expert, but my experience in a high-performance home suggests that duct placement is less of an issue when you have a tight envelope and quality windows. If I were planning a major renovation, I'd use a blower door to establish a baseline for making decisions. I'd focus on air sealing and insulation (as much as possible). If the windows are subpar, I'd consider replacing them or adding storm windows.
I'd also hire an independent engineer to develop a HVAC spec. Properly sizing the system is critical to comfort. The Manual D can guide you in optimizing the location of ducts.
You'll usually get the most even temperatures in any given room by trying to put the heat vent in the coldest area of the room (near a window, in an exterior corner, etc.), and putting the air return on the opposite side of the room, and ideally at the opposite location in terms of height (floor or ceiling) too. This gets more crossflow, so more mixing of the air, resulting in a more even temperature distribution throughout the room.
I don't really see an advantage to wall registers except for returns. Ideally you want the heat to enter at floor level. Think "stir the air" with supply and return vent placement, and try to put the supply in cold spots so that the warmest air goes into the coldest area of the room first.
Bill