Heat issues.

Hi all recently upgraded from cfl to HPs, I can't have my lights where I want them because of heat. Leaves become brittle and curl at anything below 2 foot distance.

I have a 4 inch exhaust fan but a passive inlet at about 3 quarters of the size. But since my inlet is passive can I make it larger?

Dan, what size is your room? Light size? How far is your light from your Canopy? You should have your intake low to the floor so it can draw in cooler air and your exhaust should be up higher to dissipate the heat out. and you intake hole should be 4" the same size as your intake fan. Hope you get it .

DANfour20 said:

Hi all recently upgraded from cfl to HPs, I can't have my lights where I want them because of heat. Leaves become brittle and curl at anything below 2 foot distance.

I have a 4 inch exhaust fan but a passive inlet at about 3 quarters of the size. But since my inlet is passive can I make it larger?

Click to expand...

solving problems like this: is how your learn to be a grower. my wheels are turning from stupid to brilliant ideas.

maybe you just need an A/C like everyone HPS (myself included) has too.

DANfour20 said:

Hi all recently upgraded from cfl to HPs, I can't have my lights where I want them because of heat. Leaves become brittle and curl at anything below 2 foot distance.

I have a 4 inch exhaust fan but a passive inlet at about 3 quarters of the size. But since my inlet is passive can I make it larger?

Click to expand...

Mine are 6 and 6 but the exhaust is pulling through a filter.

SoOLED said:

solving problems like this: is how your learn to be a grower. my wheels are turning from stupid to brilliant ideas.

maybe you just need an A/C like everyone HPS (myself included) has too.

Click to expand...

I get by without AC. I do throw ice in my intake filter box though, a few times a summer.

I really love that Idea Dave. Cool for sure. I am running 3 600 watt Hps and my AC hardly ever comes on. I intake from low to the ground and filter the air, It does come on when its 80 outside but that is rare where I live to get to 80 maybe 20 days out of summer.

That Idea dave has is pretty snazzy, if you have a Ice maker or store nearby that is a good way to do it if you don't have an AC unit. I may try that myself. You may have invented a great Idea for a lot of people have heat issues, I would imagine even Cold water would cool it down in the room. cutoz dave.

bravedave said:

I get by without AC. I do throw ice in my intake filter box though, View attachment 3698775 a few times a summer.

Click to expand...

that's what I'm talking about finding solutions.

that is an A/C its type of passive thermodynamics, I'm to stupid to know the scientific name for the process.

love it.

Bear420 said:

I really love that Idea Dave. Cool for sure. I am running 3 600 watt Hps and my AC hardly ever comes on. I intake from low to the ground and filter the air, It does come on when its 80 outside but that is rare where I live to get to 80 maybe 20 days out of summer.

That Idea dave has is pretty snazzy, if you have a Ice maker or store nearby that is a good way to do it if you don't have an AC unit. I may try that myself. You may have invented a great Idea for a lot of people have heat issues, I would imagine even Cold water would cool it down in the room. cutoz dave.

Click to expand...

they already have "elbow" chill boxes for grow rooms, check amazon. sometimes they have a charged plate on the top of the box, that collects evap, and adds to the cooling effect.

It's 250 w HPs, 2 foot by 2 foot closet 7 foot tall.

I have 12 inch pedestal fan positioned between the light and the canopy. Not sure to point it at the bulb or the canopy so it's just blowing straight across.


I have the light 2 foot frim the canopy now and temps near canopy are 31 degrees c, I tried bringing her down half a foot but leaves where frying.

I've now made it so my passive inlet is around twice the size of my exhaust which is powered by a 4 inch ducted fan.

No change in temps though.

sounds like its time to spend some cash upgrade your set up . its easy to fix your issue . if your willing to spend . if not then your in trouble

Bear420 said:

I really love that Idea Dave. Cool for sure. I am running 3 600 watt Hps and my AC hardly ever comes on. I intake from low to the ground and filter the air, It does come on when its 80 outside but that is rare where I live to get to 80 maybe 20 days out of summer.

That Idea dave has is pretty snazzy, if you have a Ice maker or store nearby that is a good way to do it if you don't have an AC unit. I may try that myself. You may have invented a great Idea for a lot of people have heat issues, I would imagine even Cold water would cool it down in the room. cutoz dave.

Click to expand...

Hey thanks. I have an upright freezer mostly unused that I freeze 4, 2 gallon plastic water jugs in. 2 of which fit precisely in the filter-box cooler and the ice lasts all day. It does work in knocking the temp down. I just rotate the jugs. Summer can bring a couple weeks of sporadic use. The cooler itself is used continually as a filter...as I've cut a square hole in the top and duct tape a 12x12 furnace filter to cover that so my passive air get pulled through..stopping pollen, mold, mites, dirt and more. Filter gets changed every harvest.

DANfour20 said:

It's 250 w HPs, 2 foot by 2 foot closet 7 foot tall.

I have 12 inch pedestal fan positioned between the light and the canopy. Not sure to point it at the bulb or the canopy so it's just blowing straight across.

View attachment 3698823
I have the light 2 foot frim the canopy now and temps near canopy are 31 degrees c, I tried bringing her down half a foot but leaves where frying.

I've now made it so my passive inlet is around twice the size of my exhaust which is powered by a 4 inch ducted fan.

No change in temps though.

Click to expand...

What is the temp of your intake air? Do you feel air flowing in? Seems that with only a 250 watter you should do better.

bravedave said:

What is the temp of your intake air? Do you feel air flowing in? Seems that with only a 250 watter you should do better.

Click to expand...

Ambient temp of room the closet is in is 19 to 22 degrees. I've just moved the light further away. It's 28 at canopy now but light is about 2 and a half feet away.

Where is your exhaust? It needs to be at ceiling and you may want to add a centrifugal.

Its not going to cool down any if you are exhausting the hot air from the grow room into the same area that you are pulling your "fresh air" in from. All you will do is heat the area that you are trying to pull cool air from. Completely counter productive. Can you exhaust the hot air out a window, or into a basement, etc? If not, you will need to get an A/C unit to cool the room you are pulling your fresh cool air from.

bravedave said:

Where is your exhaust? It needs to be at ceiling and you may want to add a centrifugal.

Click to expand...

Exhaust is at top of cupboard door and inlet bottom opposite corner.

Add a centrifugal?? Centrifugal what lol?

Up grade to a larger out let and use the 4 inch out let to your in let ,go with something like a 6 inch out let.

You could go and get something like a cool hood'if money is a issue then a tube till you can get a hood,

HydroRed said:

Its not going to cool down any if you are exhausting the hot air from the grow room into the same area that you are pulling your "fresh air" in from. All you will do is heat the area that you are trying to pull cool air from. Completely counter productive. Can you exhaust the hot air out a window, or into a basement, etc? If not, you will need to get an A/C unit to cool the room you are pulling your fresh cool air from.

Click to expand...

I live in north of england, it's not ac hot I'll open a window, but temps good rite now at 2 and a half feet distance. (I know this isn't good distance but it's better than crispy flowers)

You should be ok ,at that, if the plant look's ok then don't worry.

DANfour20 said:

It's 250 w HPs, 2 foot by 2 foot closet 7 foot tall.

I have 12 inch pedestal fan positioned between the light and the canopy. Not sure to point it at the bulb or the canopy so it's just blowing straight across.

View attachment 3698823
I have the light 2 foot frim the canopy now and temps near canopy are 31 degrees c, I tried bringing her down half a foot but leaves where frying.

I've now made it so my passive inlet is around twice the size of my exhaust which is powered by a 4 inch ducted fan.

No change in temps though.

Click to expand...

They look fine dude don't worry about them,by worrying about the temp's it may cause you to do something that will cause you problems,they look fine so just carry on has you are doing your doing ok...

Perhaps one of the small 6 inch clip on fans might help you,clip it onto the hood and have it blowing directly onto the bulb,there about 5/6 quid from argos,temps will lower by doing this not by much but it should lower them a bit.worth getting just in case we do have any sun this summer it's un likely,but you never know,have a look into cool tubes too there fairly cheap and really do help,