What do they know?

A project log for Warm side cool, cool side warm

A speculative DIY register booster project to even out the temps around my home.

WJCarpenterWJCarpenter 08/14/2022 at 00:340 Comments

Do you believe everything you read on the internet? I know that I do. But on this subject, there seem to be two prevalent opinions:

To be quite honest, I don't know if either of those schools of thought are correct when it comes to my own home. The people who are naysayers might actually know what they are talking about. The people who reported success might just be lucky and got good results for other reasons or despite the theoretical impediments. 

One thing that seems to be almost universally agreed, at least by anyone whose comments make it seem like they know anything about anything, is that it's a loser's game to permanently close off some registers in an attempt to force more air to others. (I'm not expert enough in HVAC to say whether this is correct thinking. I can only say that it's widely believed.) Why, then, do vent registers have adjustable louvres?  Apparently, it's so you can temporarily prevent or allow airflow into that particular room, even if it doesn't dramatically affect flow into others. For example, you might want to only heat some rooms when you expect to be using them, to save heating costs.

It's inconvenient to retrofit inline duct booster fans in my house. The rooms that need help have the ducts among floor joints or walls. The disruption to just try something is too great for me. On the other hand, trying booster fans at register* locations is just a matter of a tolerable amount of money and time.

(*Why are these vent covers called registers? Beats me. The term was unfamiliar to my adult children, but it's what I've always called them. Web searching didn't turn out a plausible origin within the limits of my attention span.)

There are a few commercially available "register boosters" on the market, and my first thought was to try one of those in one of the rooms to see if it worked. These typically have 1 or 2 fans alleged to be "very quiet" and a power cord or wall wart that plugs into a standard household mains outlet. That's not the best aesthetics, but it would be OK in the particular rooms where I need some help.

With all these market choices, why think about building my own? I don't know if it's part of the general supply chain problems or something else, but the choices I thought of as possibilities are actually kind of hard to find in stock except at dramatically marked-up prices. Maybe some container ship will arrive soon and some of them will be readily available, in which case I might abandon this DIY effort and try one.