ducting getting too hot?

Hey all,

Has anyone ever had a problem with their ducting getting too hot? I have ducting running from the back of my portable a/c (completely outside of the grow area) but after about 5 minutes the ducting is pretty hot. It doesnt seem to continue picking up heat, but has anyone ever had a problem with this causing a fire or anything? Does the insulated ducting sold at home depot fix this problem?

There is no problem with the hot ducting creating heat for the grow area, so no need to fret about that...just considering the idea of a possible fire hazard.

thanks team!

insulated ductng will still get hot just trapped by insulation

I would say this, if your duct's are too hot to touch then something is wrong. I mean if you can't leave your hand on it for 5 minutes with out burning it you need to check your a/c out. Just my opinion though and YMMV.
KnB

the exhaust from an a/c-

get s hot. you cannot put you hand on it for five minutes.

take your thermometer and lay it on the duct. put a washcloth over it for 30 seconds or a minute. that should give you a rough estimate of your temps.
the duct you are using will have a temp rating. i would imagine flex duct is fire rated.

if not. use hard pipe(cheaper than flex). they also make rigid, flexible aluminum ducting (more expensive than flex).

What is the temperature of the space that you have your a/c in. A/C systems works by taking ambient air(air where your a/c condenser is) and flowing it accross the condenser where it picks up heat from the refrigerant. There is typically a 30F diffrence. If your ambient air temperature is high then your exhaust temp is going to be even higher. If you can somehow lower the temperture where your condenser is then you will lower the exhaust temperature.

I am under the impression that this is a self contained unit, not a split system like your main a/c for your house.

I had a portable ac and the exhaust run was so long it actually ended up radiating enough heat to not even drop room temps more then 3-4 degrees. Brought the unit next to a window and shortened the exhaust run to about 2 feet and my temps went down another 5-6 degrees. I ended up getting rid of the portable. POS, my new 5000 btu window unit outperforms the 10000 btu portable.

I never had problems with a fire or anything, it just didnt cool my room down.

Thanks everyone, some good info here. Luckily I am able to run the ducting out of the room immediately so the radiating heat is not an issue. The only concern I really had was with the ducting heating up too much and some how starting a fire. HOWEVER, I just called a local air conditioning company and asked them about it.


useful info:
the likeliness of the ducting getting to a temperature where it caused a fire is unlikely, However they mentioned that dryer fires are possible with lint being caught in the ducting (he just threw this info in on a little tangent he went on ). Insulated ducting reduces the radiating temperature by almost 70%, and he highly suggested it. He also told me to purchase some insulation and tape and wrap the ducting joints, as this will greatly help with heat also.


Hope this helps with anyone else! thanks again for the answers!

HI thanks for the info i have got the same problem, just bought a portable a/c unit and my ducting is HOT you carnt put your hand on it for 5mins anyway would love to see someone try lol!
This has been great info thanks!

my portable 10K-
works great.

The likelihood of something starting a fire depends on the autoignition temperature of the materials coming in contact with it, or materials within a few inches of it where the radiant temperature hasn't dissipated much. To give you a ballpark idea here, the autoignition temp of gasoline is roughly 500 degrees F.

Yeah lol, 5 minutes is a pretty long time. I meant seconds and apologize to the op. I was just trying to say that your vent shouldn't bed red hot or near hot enough to start a fire. I feel bad because I am imagining someone now burning the shit out of themselves on my advice, also for any of you having problems with your ducts being that hot my advice is to add a duct boosting fan. You wouldn't believe the efficiency you can add to your a/c paired with insulated ducting it's a win. The fan I speak of is one of these just for reference. Once again my apologies to the op, good luck and happy growing.
KnB
also they have a video of the fan in action for those not sure of what it is still.

Thanks fireproof that was exactly what I was looking for! I ended up covering everything with insulation, and now the ducting went from being very hot (almost too hot to touch) to not even a few degrees of temperature change. the 4" insulation was $25 for 25 feet. I only needed about 6ft for the portable a/c, so with the extra I sliced it open and used it to wrap the ducting joints and other ducting. Stuff is amazing.

help please my room is between 30-35 degrees and im using a cooltube setup with air being pulled in from outside through 2x600hps and then through ruck inline fan, seperate to that i have another ruck fan pulling through a rhino filter can you help me in any way please???

gangaguru, Welcome to the forum For lots of info you can use the search bar and normally find lots of answers. There is a good sticky on proper ventilation techniques, and really good info that may help you with your problem.


OTHERWISE..... What is the temperature of the outside air being brought into your room? If it is not less than 70-75 degree's then you are going to need an air conditioner or water chiller/icebox set up. The air being moved by the fans is not enough to lower the temperature in your room. Also check for the temperature of the air at night. Maybe it is within range, and you could run your lighting cycle at night to help.

If your ducting is radiating heat inside the grow room, I suggest doing what I did in this thread, and covering all ducting with insulation. it is available at home depot for 25$ for 25' 4", 6" or 8".

Your ballasts, fan motors, air pumps, external hydro pumps, all create heat also, Which can also bring up temps.

Hope this helps

thanks for the info i have put a/c into the room and temps are down to 27-28 so am gna go with that lol air temps outside are 18-21 and night temps are down to 17 in the room. beans are a go!!!