Submitted by flyingGoatPenis t3_zpa1mk in DIY
BxMxK t1_j0rpvpc wrote
You also need to make sure the rest of the ductwork can handle the increase in pressure from closing off one of the ducts.
I've seen more than a few main ducts burst open because people thought they could just cover a register or two in rooms they weren't using and didn't take into account that the blower was still trying to move the same volume of air through less openings.
monthos t1_j0sbro4 wrote
After working in telecom/IT for so long now I decided if I ever build or renovate a house I am putting in a home equivalent of a BAS system.
Multi stage heating and cooling, PWM controlled supply fan, dampers to limit airflow from the air handler all so each zone can be set to different temps, but keeping the static duct pressure in the optimal range.
Gr3yGhost t1_j0se9gn wrote
My house is built like this. Built in 2018. The HVAC has 3 zones, 1 for the master, 1 for the living room, and 1 for the 2 lesser bedrooms on the other side of the house.
It works great when I'm just chillin in my office/game room and it gets toasty, I can just close the other 2 dampers so that only the game room is fed all the cold air I am requesting. And because I'm only cooling a small room thats about 350sq-ft at most, it cools it off pretty damn quick. Also helps that each zone has its own intake vent also
Aurum555 t1_j0t7xqr wrote
This only works with a well insulated house otherwise you end up just spending extra money for your system to fight itself,that said I'm insanely jealous, and want to reinsulate my e tire house so I can even dream of doing something like that.
Semanticss t1_j0s84eg wrote
Agreed. Closing just one duct has tripped my blower fan in the past from the change in air pressure.
Might need a professional for this. But honestly, best thing to do is leave the vent. I don’t see any reason to remove it other than the slight inconvenience of furniture positioning.
MattsAwesomeStuff t1_j0ufg6k wrote
> Closing just one duct has tripped my blower fan in the past from the change in air pressure.
That's not how motor load on a fan works.
The more you block it up, the lower power the fan consumes.
This is counterintuitive to some people, but is a fact.
WKS01 t1_j0v6gpa wrote
That is not entirely true, it depends on the type of fan being used. In a constant torque motor the fan would increase amp draw as it attempts to overcome the higher external static pressure.
MattsAwesomeStuff t1_j0vgyqm wrote
> In a constant torque motor the fan would increase amp draw as it attempts to overcome the higher external static pressure.
... is that the type of fan used in whole-house HVAC systems?
... no.
[Edited to add, see below, in some cases, actually yes]
WKS01 t1_j0vlqkl wrote
There are Manufacturers that do use constant torque motors in residential furnaces though. Trane S8X2 S8X1 and S8B1, Carrier Comfort and Performance series, York TM9Y, Bryant Preferred and Legacy Line are just a few that use constant torque motors for the blower fan. Basically every Manufacturer offers a lineup that consists of different series that use VCA (Variable Speed Constant Airflow), VCT (Variable Speed Constant Torque) and FCT (Fixed Speed Constant Torque).
MattsAwesomeStuff t1_j0vvvlf wrote
TIL.
Thanks.
skippingstone t1_j0tb3w7 wrote
Is there a way to change the blower settings?
BxMxK t1_j0tjk9x wrote
Really depends on the unit.
Multi-zone units typically have variable speed motors.
Single zone units usually have single speed motors. Some have blowers mounted directly on the motor shaft. Some are belt driven. With a belt drive you have a little flexibility to swap pulleys to adjust he cfm.
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