Optimizing central heating and AC vents

I am attempting to optimize my vents and am seeking tips. I have some unused rooms, but when I flip the little lever on the vent grate on the ceiling, it still allows quite a bit of air through.

My solution was to cut out a cardboard panel the exact size of the vent behind the grate and obstruct the vent using the cardboard. However, my plan worked a little too well as now zero air is coming through the vent.

Should I be concerned with blocking off one of my vents so completely? Will I cause damage to my central furnace? Will there be any fire danger when I turn on the heat in the wintertime? :eek:

It seems my remaining vents are getting a lot more airflow, but that ended up making those vents noisier. The wind is practically whistling through my bedroom vent now. Eh, more adjusting needed, I guess.

No, you won’t hurt your blower by obstructing a vent, and there is not a fire danger as the air is not anywhere near hot enough in a central system to cause a fire. It’s not much different thatn closing a vent in your car - it just routes approximately the same volume of air but to fewer registers.

I would keep playing with your cardboard damper. If you want to hide it, I would cut it out lthe right size to fit on the underside of the register. You can usually just grab the register and pull it out of the floor to gain access to it. Then, experiment with different hole sizes until you get the airflow you are are looking for.

Well…Within reason…

I’m an HVAC contractor (beltbuckle may be also) and know a fair amount as I do this for a living. Closing off 1 register is generally not a problem. more than one and you may have problems—although you may not be aware of them.

A furnace requires the amount of airflow designed for it. So does the A/C. If the airflow is diminished there is additional heat ‘buildup’ in the heat exchanger in the furnace and the system will often shutdown prematurely from safetys built into the furnace. Often, the safetys will turn the firnace off and on repeatedly and the homeowner is unaware. If you restrict enough airflow the furnace’s heat exchanger will wear out prematurely due to heat stress (not moving that heat into the home because of closed registers) and can destroy a central air conditioning system if not enough air flow crosses through the furncace. Worst case, there is a fire hazard, although unlikely.

Now that I’ve scared you…Closing off **1 **register is likely to do just what you planned/hoped. It will restrict flow to that room, and the air (following the path of least resistance) will be redestributed elsewhere in the house. No problem. just don’t close too many, and generally never close off a return grille/register.

Good tip, raindog… I had actually been closing off a lot more of my registers during my experimentation process. Good to know that I shouldn’t really be doing that.