# Air deflectors



## house92 (Oct 13, 2019)

I would like opinions on the use of air deflectors on floor registers. Is it best to let air blow up on the wall or use a deflector and blow it across the floor? I’ve read both ways. Some articles say it should blow straight up and warm the walls and windows, while some say blowing it on a cold window is less efficient and it’s better to scatter the air across the floor. Or, could it be option three, which is like most things similar to this: 3. It probably doesn’t make a noticeable difference either way even though some claims it does.


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## kok328 (Oct 13, 2019)

I use them every winter.  I have vaulted ceilings and want the most out of my heat before it goes to the peak and sits there.
The deflectors I use don't cover the whole register.  Register is 4" and deflector is 3" so I let 1" of air go to the wall/window and 3" of air to go across the room before rising.
They are also adjustable in length so you can tune them in to meet your comfort needs.


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## slownsteady (Oct 13, 2019)

Since heat rises naturally, why not slow it's ascent with the deflectors?


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## house92 (Oct 17, 2019)

Sounds good to me. I’ve just read so many different views. As with anything, there are a million opinions on everything. I think I’ll go with deflectors for now.


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## pjones (Oct 26, 2019)

The reason registers are positioned under windows and along walls is because that is where your heat loss and heat gain are.  The deflecting the air to the middle of the room will only make your temperature gradient larger when walking from the middle of the house towards the outside wall. It seems counterintuitive because you think you want the heat to go to the middle of the house but in reality you have very little heat loss or gain in the middle. Keep the heat and cooling near the outside and the inside will regulate itself as it was designed... this is also why the floor registers direct the air along the wall instead of towards the middle of the room.


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## bud16415 (Oct 26, 2019)

I agree and also the reason in the winter I reverse the direction of our ceiling fan to blow up and across the ceilings and down the walls.


Ceiling fans set on slow in the winter can be of great help with keeping the room a uniform temp. In the summer you welcome the feeling of air movement but in the winter you don’t want to feel the movement but you do want to bring the warm air back down into the room.


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## house92 (Oct 26, 2019)

Again, there are different opinions. The bottom line question is, “does it really make any noticeable difference?”  I’ve tried both, and the only difference I see is that with deflectors in winter, I actually feel the air circulating, which I like, but I haven’t seen any difference in the bill or overall temperature of the rooms. What about the walls and windows that don’t have a register at all? So, technically, I’m sure there is a difference, but does it amount to a hill of beans?


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## bud16415 (Oct 26, 2019)

house92 said:


> Again, there are different opinions. The bottom line question is, “does it really make any noticeable difference?”  I’ve tried both, and the only difference I see is that with deflectors in winter, I actually feel the air circulating, which I like, but I haven’t seen any difference in the bill or overall temperature of the rooms. What about the walls and windows that don’t have a register at all? So, technically, I’m sure there is a difference, but does it amount to a hill of beans?


I would say in terms of energy used there is no difference or a very small hill of beans. In terms of keeping the temperature equal within the room the deflectors may or may not help depending on how well the system was designed.


If where you sit and watch TV feels better with one then I would go for it.


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## house92 (Oct 26, 2019)

bud16415 said:


> I would say in terms of energy used there is no difference or a very small hill of beans. In terms of keeping the temperature equal within the room the deflectors may or may not help depending on how well the system was designed.
> 
> 
> If where you sit and watch TV feels better with one then I would go for it.



I have digital thermometers in every room. Today, I have my heat on 68, and with deflectors, every room reads 68. Without the deflectors, I assure you my front room would be 70, and my back room would be 66 or 67. With that, I assumed deflectors were better, so I decided to research and read about how they help. During that research, I came upon the idea about heating the wall and windows, which made deflectors seem to be not such a good idea, but they seem to work for me.  I just wanted to get opinions from users to see if I was somehow shooting myself in the foot even though the deflectors seemed to create a more pleasant environment in my house. 

Maybe it depends on how the house is laid out. I live in an older farm house. All my rooms are connected by doors. In other words, I can walk in the front door, take a right, make a circle through the house, and eventually end up back at the front door from the left.


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## pjones (Oct 26, 2019)

All we can tell you is how it’s supposed to work on a properly designed house. How it actually works depends on the quality of the installation, quality of the insulation, placement of your furniture. Installation of drapes where they were not originally planned at the time of design. quality of the windows, quality of the vapor barrier, placement of your thermostat, weather or not rodents have degraded your vapor barrier and insulation, number of people in your house, equipment that you keep in each room,...the list can go on and on...

I would suggest doing what makes you feel most comfortable. Now you know how it is SUPPOSED to work on paper. Reality is always a different story. The problem is, a poor job done by a different trade can result in poor performance from your HVAC. If the insulation of insulation wasn’t preformed correct it’s effect would be quite obvious because now, for example, the ceiling may not have the correct thickness of insulation on it, or it may have a hole in the insulation, now causing heat losses and gains where they were not designed to be. The deflector may be a solution there. An electrician or a plumber may not have sealed up their holes that they drilled allowing for infiltration into a room. The result seems like the duct was undersized but the reality is it was sized right for the load but the additional load created by the other trades was never supposed to be there and that new load was not accounted for. 

Everybody makes mistakes. Maybe it is best to have another register under a window that didn’t have one. Maybe it was in the plans but the builder didn’t want to add a required bulk head to make it possible so they said they would put a baseboard heater there instead, then never followed through with it. Owners never know when they buy a used house or quite often a new one, if all the plans were followed to a “T”

In reality, bedrooms turn into computer rooms or games rooms that include additional heat load from computers, TVs, stereo equipment, an unfortunate number of human bodies, and the room gets the complaint that it’s always too hot, the AC can’t keep up. But if you provide enough airflow to that room to keep it cool on those few days when company is over then every other day when it is not being used will be like a fridge. That can be planned for during design but after the fact it’s very hard to resolve that. Walls get moved. Walls get added. If you are walking into a used house you may inherit the problems that go along with those modifications. What used to be an open area is now enclosed with a very cold hallway because it no longer has heat eat supplied to it even though it runs the length of the house with a window at the end... this of course is all hypothetical, but these examples happen all the time. 

Your heat load doesn’t change when you add deflectors, just your comfort level... (and ductwork static pressures, but that’s probably better left for a different thread)


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## house92 (Oct 26, 2019)

I appreciate the lengthy explanation. It sounds like there is a perfect situation on paper, but that perfect situation rarely exists in reality.  It can be altered by furniture placement, number of people, insulation, electronics, etc. I’m sure HVAC units are installed according to that perfect situation, which they should be.  I’ll also bet that there are thousands of different home situations that alter the performance.


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## rbm328 (Oct 27, 2019)

i am using several deflectors.  i live in north alabama, and here they put the registers in waaaay before anything else goes in. so, i have two vents underneath cabinets (kitchen and bath).  then, my wife loves to put furniture over vents.  i found a place online that sells deflectors that i can extend past the kick board on cabinets and the front of the furniture.  i believe it helps -----it can't hurt!

https://www.amazon.com/Deflecto-Fur...ocphy=9012761&hvtargid=pla-425064180697&psc=1


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## slownsteady (Oct 27, 2019)

Unless you have a blower with the horsepower of a lawn & leaf blower....or unless you deflector is verrrrrry long, I doubt you are moving the heat very far from the wall.


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## pjones (Oct 27, 2019)

rbm328 said:


> i am using several deflectors.  i live in north alabama, and here they put the registers in waaaay before anything else goes in. so, i have two vents underneath cabinets (kitchen and bath).  then, my wife loves to put furniture over vents.  i found a place online that sells deflectors that i can extend past the kick board on cabinets and the front of the furniture.  i believe it helps -----*it can't hurt![\B]
> 
> https://www.amazon.com/Deflecto-Fur...ocphy=9012761&hvtargid=pla-425064180697&psc=1*



It can increase friction and therefore reduce airflow. If you do that to too many registers, or if you had poor airflow to begin with, then it can cause problems and hurt your heat exchanger. There is a lot to consider when determining that so it’s not a blanket statement, but something to be aware of.


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## house92 (Oct 27, 2019)

slownsteady said:


> Unless you have a blower with the horsepower of a lawn & leaf blower....or unless you deflector is verrrrrry long, I doubt you are moving the heat very far from the wall.



I agree, at least, it’s not blowing it far enough that it defeats the purpose of the register locations, but the small change does seem to make it more comfortable for me. I have one room that is 15’ wide, and when I’m sitting on the other side, I feel the warm air when it kicks on, and it seems to equalize the overall temperature throughout the house better than without deflectors.   I also feel the air circulating regardless of where I am in the house, which I like, but I didn’t without the deflectors.  If my bill goes up 10% and I get icicles on my outside walls, then I’ll know I had better take them off. 

Regardless of the topic, there are so many ideas out there that people swear by, but the difference is so minuscule, it doesn’t amount to a hill of beans. There are always ideas about things. Remember the days when it was believed that more energy was saved by setting your thermostat and leaving it, even if you were going to be away from home 8 or 10 hours every day?  Back then, some people acted like anyone who believed otherwise was an idiot.


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## rbm328 (Oct 27, 2019)

slownsteady said:


> Unless you have a blower with the horsepower of a lawn & leaf blower....or unless you deflector is verrrrrry long, I doubt you are moving the heat very far from the wall.


i don't understand??  the heat/ac can either roll around in the cabinets cavity or it follows the path of the deflector.


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## house92 (Oct 28, 2019)

rbm328 said:


> i don't understand??  the heat/ac can either roll around in the cabinets cavity or it follows the path of the deflector.



True. I lived in a house once where the registers were under the cabinets in the bathrooms, and a hole was cut on the bottom of the cabinet and a grill put over it. The air just trickled out until I managed to get a deflector on underneath the cabinet, which wasn’t easy. As you said, the air was just rolling around under the cabinet before.   I’m sure that was considered the most “out of the way” location for the register, but it made no sense that me.


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## bud16415 (Oct 28, 2019)

house92 said:


> Remember the days when it was believed that more energy was saved by setting your thermostat and leaving it, even if you were going to be away from home 8 or 10 hours every day?  Back then, some people acted like anyone who believed otherwise was an idiot.


 I had a friend that’s wife wouldn’t leave the setback alone on the Tstat he had it set to back the temp down during sleeping hours. He placed a little end table below the Tstat and put a lamp on it on a timer telling her he wanted a night-light. She thought it a good idea and he solved his heat problem


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## slownsteady (Oct 29, 2019)

rbm328 said:


> i don't understand??  the heat/ac can either roll around in the cabinets cavity or it follows the path of the deflector.


I was referring to the deflectors, not the under-cabinet vents.


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## Jeff Handy (Nov 21, 2019)

Sometimes if you use deflectors, you will get a short blast of annoying cool air shooting at you when the blower first kicks on. 

Also, you can sometimes get more condensation or icing on a window over a vent that is diverted by a deflector.


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## house92 (Nov 21, 2019)

Jeff Handy said:


> Sometimes if you use deflectors, you will get a short blast of annoying cool air shooting at you when the blower first kicks on.
> 
> Also, you can sometimes get more condensation or icing on a window over a vent that is diverted by a deflector.



I have noticed the burst of cool air, but it only lasts a couple of seconds, so I’m ok with that. I still believe it heats the living space more evenly in my house.


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## Jeff Handy (Nov 21, 2019)

That little cold blast wakes you up, telling you it’s time to change the channel or to get a fresh beer, haha.


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