I come to sing the praises of some duct boosters I put in a while ago:
We have two areas which have a problem with heating/cooling. One is a 4-season raised porch which is exposed to the weather on 5 sides. Worse, when they converted it from “deck” they I only put in one floor vent; every other room in the house has at least two. Even worse, they ran flexible ducting to it which, because of the ridges, doesn’t pass air as efficiently. And last worst, they didn’t even use insulated ducting, so since it runs next to the underfloor (which is exposed to the weather) it gets about 10 degrees colder before it even gets to the room (yes, I measured), and because it used to be a deck it has to travel an additional 15 feet from the main hvac duct, which is already at the extreme end of the house.
All of this conspired to make the room at least 20 to 30 degrees hotter or colder than the rest of the house, depending on the season. In winter we were running two space heaters to get it to temperature for our morning coffee; in the summer two window A/C units. Expensive!
I tried other things, including “booster fans” from Suncourt, which trigger when they sense heat coming from the vent, trouble was by the time they sensed heat the main house was almost already at temperature so the “vent booster” only ran a few minutes. (Even with an actual booster fan embedded in the duct [yes, I tried that too] it wasn’t much help.)
Then I discovered this, a different kind of vent booster:
https://www.amazon.com/AC-Infinity-Register-Thermostat-Contr…
It sits flush to the floor, so it’s less obtrusive than the old style that looks like a shoebox sitting on your vent. Better, it’s programmable simultaneously for hot and cold temperatures, which doesn’t sound like much until you realize the power of that:
I program the fan to run when it senses (say) 75 degrees in heat mode. I also program it to run when it senses 68 degrees in cold mode. So now I have a 7 degree “comfort” mode. When the heat comes on, it’s either already running (pulling the air down the duct better) or not (in which case the natural flow down the duct is barely needed.
When the heat goes off the fan keeps running for a while, extracting the heat that’s left in the duct. And if the room is still too cold, it keeps running and actually pulling air down the ducts from other rooms and into the sunroom until the house is balanced. Yes, that’s using the ducts backwards, but it works! It’s the best of both worlds. If the room is cold the fan is running; when the heat comes on it pulls more into the room. If it’s still too cold it keeps running until it’s close to sync with the rest of the house.
That sounds like a lot of “fan running”, but here’s the thing: My Kil-a-watt says it used 0.03 kWh in the past 24 hours. The fan is speed adjustable 0-10. It is silent from 0-5, barely discernible to 7, and from 8-10 about as loud as the old ‘shoebox type. Better, it “ramps up” and “ramps down” so there is not a sudden jolt of noise.
The second area that needed help was my workshop, which occupies an area we had excavated under the other wing of the house and which came with no hvac infrastructure at all (except for ductwork to feed the bedrooms at ground level above.) I had already cut holes in the ducts and installed vent grates, but it wasn’t enough, and it still got very cold in winter. (Summer was OK because: basement.) I put two of these things in because the room is over large, and the same thing is true: I can now walk in and not freeze to death waiting for two space heaters to bring the temperature up.
Same trick: program both heat AND cool to provide a comfort zone, and let them do their thing. These have only been in place for a week in the workshop but they do the job.
I expect to save money not running high-amp space heaters (or A/c) for several hours a day and by running very low wattage fans for several more hours. The larger and original house hvacs will run a little more, but that’s OK; it’s geothermal hvac and quite efficient.
We’ve talked about this sort of too hot/too cold hvac problem here before and I thought I would pass along a better solution I’ve found.