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Air conditioning and scent throw

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After testing at least 9 candles over the last week I was just about ready to throw my candle supplies into the trash and save what little sanity I have left.:P Everything I have tested gave me little to no hot throw! All of these candles have cured for 1-2 weeks and are paraffin. I just could not understand what was going on! I tried different wicks, no change! I did notice that if I opened the room door the scent throw IMPROVED slightly. I know some people swear by testing in small closed rooms but I find the increase air circulation just from having the door open helped. So I made a couple of candles using FO's that normally work very well for me and usually require just a couple of days curing time to give me a good throw. Guess what? Very light hot throw once again! :mad: After reading my notes I realized that this occured last summer with several candles. When I tested candles made with the same FO %, wicks, wax...again around October I noticed a much improved hot throw. The only thing that is different is the use of air conditioning. So after the air was off and the house temperature is at 71 I re-tested a candle and it has much better scent throw. Ok, maybe I figured out the problem but you can't exactly tell people to only burn your candles when air conditioning is not in use. Anyone else notice this in your testing?

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yes I do! and I do tell my customers this! They know I am a rigid and abusive tester and they know I am telling the facts! LOL Also if you smell a lot of fragrances your smeller gets immuned to it! LOL That is why I finally moved out of my kitchen to my work area in the basement!!!! So when I test a candle I can get an honest scent throw test! HTH

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I notice certain parts of the house have a good scent while other areas do not-the fan pushes the scent around in my house. But I still get good throw. I am in Florida so all scents must throw under pretty all conditions including air conditioning or being used outside. I make mine candles pretty strong to combat this situation.

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The AC definitely effects a test. We have a central unit, and it sucks some of the scent right to it (around the corner from where I put one of my candles). Although it does scent my living room, boy can you ever smell it in that hallway;)

In theory, the heat in the winter should do the same thing, but it really doesn't effect it much at all--go figure?

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I noticed this last summer also. My theory was that it was circulating the scent in a closed home so it was everywhere and I was immune to it. hmmm But, as dabble said, it should do the same in the winter. It doesn't. I have no answers. Since my son is allergic to cold, I dont' run the AC much anyway. I just don't test when it's on.

I also tell customers that AC will affect the throw.

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  • 4 weeks later...
In theory, the heat in the winter should do the same thing, but it really doesn't effect it much at all--go figure?

I'm NO Expert...

The reason is that your Furnanice and your Candles both produce the same kind of heat which is called DRY HEAT.

Where as your air conditoner produces Cool-air and therefore produces a Cool-moist air...

Or moister than your Furnanice anyway...lol...

ANYWAY... What it boils down too is...

In the Summer... When running your A/C you are continually taking humity out of your house... So your candle has to compete with constantly changing conditions.

Where as in the Winter Running your Furnanice, the conditions stay pertty much the same Warm & Cozy...

Because Probably very few of us turn our heat OFF in the winter once our house is warmed up it stays where ever we set the thermosate...Therefore the humity is consistant.

Anyway what I was Trying to Point out is that...

Your Candles Fighting the A/C... Is more less...


Which is what produces Thunder in Nature...

I would friendy suggest to make sure your testing away from a cold air duct... so it is not sucking all the fragrance out of the room...

Thats my theroy anyway... just a thought...





Kind of like Balincing a check book... mixxing +'s and +'s and +s is great.

But; when you start mixing in -'s with those +'s things can go in the red really fast if your not carefull...

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I'm NO Expert,

But here is my $0.02 anyway...

The colder the candle is the slower it will burn...

Thats why some put theirs in the refigerater for 24 hrs before each light... to achive a longer burn time...

But Unknownly to them they don't know that the heat is what throws the FO,

So When You run your air in the summer your candle is burning slower than it is in the winter because the ambiet air is cooler

---And therefore makes the candles ambiet tempiture a littler lower than it is in the winter...

-------------I think scent throw also has alot to do with ambeit temps... AS-IN the Tempiture around the candle...

Like I Said IN My earier post. post #7 it is Cold-air...fighting...Hot-air...

--------Just My Opion-------Frank...

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I have known this has been a problem for me for a couple of years now. Summer is when I finally have the time to test burn and get ready for the busy season. Only I can't get a scent throw in the summer with windows open or the A/C on. I switched waxes, wicks, rooms, f/o's, you name it. Nadda. Florals and fruits do seem to throw a little better this time of year. So, I try to work on those in the summer and scramble trying to test the bakery and food scents in the early fall. I feel silly telling my customers this though. They might think I am making excuses for my candles not producing much scent throw. It DOES sound far-fetched, but it's TRUE!:Werd::confused:

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If any of y'all are allergic to as many molds and dust and mites and stuff as I am, being shut up in a house all day with that stuff, how would I even KNOW if a candle was tryin' to produce good hot throw?!!!:confused: It's not so bad for me in the winter, because down here, there are relatively few days in the cooler months that we cannot open up the windows and doors...

I thought the comment about the return air sucking the scent up was pretty good...


Which is what produces Thunder in Nature...

So THAT's why I can't smell it - it's thunderin' too loud!!:D I'm just pullin' your leg, Melts... don't shoot me!!:tongue2: It's been a long day and I'm just bitter because I am so stuffed up I couldn't smell a monkey fart in an elevator!:laugh2:

I think the theories that everyone has shared have some ring of truth to them... I don't notice the lack of hot throw that much because my ol' house struggles to keep up winter and summer... I think I'd have a better chance of smelling a candle outside right now...:)

Hey - you ever notice that stuff that is chilled - like from the fridge or freezer - doesn't have much scent throw, but as soon as you heat it up - VOILA!! Dinner's Ready!!:) That's my favorite theory - scents throw better in warmer temps than they do in cold. That's my story and I'm stickin' to it... unless someone comes up with a better one...:D

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  • 1 month later...
  • 13 years later...

I realize this thread is just about 14 years old, but I too am experiencing the same issue.  Bringing it back around to see if anyone else is also noticing this phenomenon.  


I’m testing with 464 - Pumpkin Souffle at 6% and 8%, and with 6006 - Cranberry Apple Marmalade at 7%.  Cured since January / February.  The 8% Pumpkin Souffle is older than that.  Other scents behave the same way.


In the winter and spring, bam, in your face and up your nose.  Can’t miss it. 


But now in the summer with the AC on, notha.

I burn a candle and smell the scent just fine, and when I turn on the AC, in minutes, the scent is just about non existent. Doesn't matter the scent. But once I shut the AC off, in minutes the scent comes back.  I’ve even burned for a few hours with the AC on to see if the scent “catches up”.  Nope.


I’m assuming it must be the cold heavy air dropping and affecting the scent throw somehow.


I can have the heat on in the winter and it would have no affect.  I also tested a couple of weeks ago with some windows open for the fun of it and I could smell throughout the rooms.  Which I was extremely surprised.  I thought for sure the scent would just go out the window and smell nothing whatsoever. 


I do not have central air either.  So there are no vents in the room I test in.  I have a mini split about 20 feet from where I usually test the candles. And I have it directed away from that room.  I’ve also tried different rooms as well.  Once that AC unit kicks in, the scent vanishes.  And it’s not super cold either.  Maybe around 68 to 70.  Which is what it usually is in the winter with the heat on. 


So it’s just with the AC on is when this happens.


I can't be the only one this is happening to.  Can I?


I would have to think those living in the warmer climates have the AC on a good part of the year.


With that being said… do you test in the summer or more so from fall to spring or do you not have any issues and go year round?

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Let's start with this from last year.


Cold air from AC or hot air from heater has nothing to do with this since our room will be cool off or heat to our liking temperatures which would turning into our ideal temperature room.  We turn on AC because room is hot.  So, we are actually dealing with hotter air when we turn on air.  And we turn on heater because room is cold. 


It's the air flow caused by those mechanical system causing HT to travel to undesirable spot within the house or out of the house.  Most heaters are designed to heat and trap air inside the house, and ACs are designed to force hot air out of the house even though natural ventilation will force air out and bring in more air all the time.  So, is there a solution to this in candle making?


Best way to solve this problem is to design a candle with weak air current.  I try to find coolest burning wick that will produce below Yellow Arrow kind of air current.  It will keep most of HT within the room, but it will still goes to other room with air flow of the house.  At least, this will reduce HT from being escaped to outside when AC is on.  And this works well for sitting position and standing position.  I am not saying this would be the only solution.  It could be just one of several different ways to solve this. 

*I see so many candles that will only work well for standing position because air currents from the flame is too strong.  And some, HT is nonexistence in candle burning room because of strong air currents from the flame.



More information can be found online if you search "Natural ventilation and Mechanical or forced ventilation of a house" for better understanding, but below is some simple explanation.  Good luck and have fun!


Mechanical or forced ventilation[edit]

Mechanical, or forced, ventilation is provided by an air handler (AHU) and used to control indoor air quality. Excess humidity, odors, and contaminants can often be controlled via dilution or replacement with outside air. However, in humid climates more energy is required to remove excess moisture from ventilation air.

Kitchens and bathrooms typically have mechanical exhausts to control odors and sometimes humidity. Factors in the design of such systems include the flow rate (which is a function of the fan speed and exhaust vent size) and noise level. Direct drive fans are available for many applications, and can reduce maintenance needs.

In summer, ceiling fans and table/floor fans circulate air within a room for the purpose of reducing the perceived temperature by increasing evaporation of perspiration on the skin of the occupants. Because hot air rises, ceiling fans may be used to keep a room warmer in the winter by circulating the warm stratified air from the ceiling to the floor.



Natural ventilation[edit]

Natural ventilation is the ventilation of a building with outside air without using fans or other mechanical systems. It can be via operable windows, louvers, or trickle vents when spaces are small and the architecture permits. ASHRAE defined Natural ventilation as the flow of air through open windows, doors, grilles, and other planned building envelope penetrations, and as being driven by natural and/or artificially produced pressure differentials. [2]

In more complex schemes, warm air is allowed to rise and flow out high building openings to the outside (stack effect), causing cool outside air to be drawn into low building openings. Natural ventilation schemes can use very little energy, but care must be taken to ensure comfort. In warm or humid climates, maintaining thermal comfort solely via natural ventilation might not be possible. Air conditioning systems are used, either as backups or supplements. Air-side economizers also use outside air to condition spaces, but do so using fans, ducts, dampers, and control systems to introduce and distribute cool outdoor air when appropriate.

An important component of natural ventilation is air change rate or air changes per hour: the hourly rate of ventilation divided by the volume of the space. For example, six air changes per hour means an amount of new air, equal to the volume of the space, is added every ten minutes. For human comfort, a minimum of four air changes per hour is typical, though warehouses might have only two. Too high of an air change rate may be uncomfortable, akin to a wind tunnel which have thousands of changes per hour. The highest air change rates are for crowded spaces, bars, night clubs, commercial kitchens at around 30 to 50 air changes per hour.[16]

Room pressure can be either positive or negative with respect to outside the room. Positive pressure occurs when there is more air being supplied than exhausted, and is common to reduce the infiltration of outside contaminants.[17]




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@SRez  Oh!  You found another great thread that gives me good idea.  I think I want to play with fog machine to see how air flows inside the house and also check out the strength of the air current from the flame.  Fog is going to be more accurate than feathery puff air balls that floats in the air.


We cannot control where customers would be placing their candles.  However, we can assume that most of them are going to be placed about 2 to 3 feet above the floors.  And we have to do our best to create a candle that would work well from that height.  In my opinion, the one that throw about 1 foot upward from the flame would work better than the one with 3 feet throwing power.  But then, I guess there is not much we can do about where air flow goes from that height.

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@BusyBee that's a pretty good idea with the fog. I assume it would be a little bit more denser than regular smoke but still give the same traces.

I know it has been mentioned that hot and cold ancient temps do not make a difference in the hot throw, but I've seen first hand here that there is a difference. At least in my experience in my house. The heat and the AC come from the same mini split unit. 

Anyway, what kind of life is it without a little bit of challenge anyway? 😁

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Welp... I think I may have spoken too soon. Ha! Go figure. 

This candle has been burning for a few hours and I can smell it throughout a couple of rooms. Granted it took a little bit longer to spread throughout the rooms than if the AC was off, but it eventually did. The scent is a bit diminished, but the scent is there. 

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Hot and cold room will definitely affect HT.  But cold air from AC or hot air from heater would not affect the HT as much because it will be mixed to cool down or heat up the room to our desired temperature.  It's just that air currents from AC is going to be more stronger than air currents from heater and will create strong air currents in the house.  And a house is usually designed to force hot air out of a house when AC is running, so, HT which could be considered as hot air would be escaped out of house more when AC is turned on.  I don't know!  This is just my wild theory without scientific backing.  Yes!  What kind of life is it without a little bit of challenge? 😄

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