Grow Cupboard ventilation ideas - help please

Hi, i'm a uni student and a nube to this so naturally i have done A LOT of research but am still getting to terms with the physical aspect of growing. I have a cupboard above my wardrobe, not very big (H 3ft, w 2ft, L 6ft) and am attempting to grow 6 plants. I realise i can't grow them very high which is ok so i am opting for density.

I am on a tight ass student budget of nothing, but have got a 400w hps in there but no ventilation yet which i realise is very important. I have got 3 computer fans, and a normal desk fan but also with a chimney built into my wardrobe so i am going to take advantage of that - i'm just not too sure how.

I originally used emergency blankets in there, but that made everything waaay to hot as they are designed to keep heat (dah) so i swapped to a flat white paint.

I'm running an 18hour light period, origonally with 1 clf and putting them in the sun each day. but i have swapped to the 400w.

With the doors open the temperature is steady at 26 Degrees Celsius, but when shut sores to 40+. My plants got a bit burnt this morning when i was sleeping but after a day of monitoring temperature they have recovered.

***The other thing is, i don't really want the smelly smell in my room if i an avoid it, hence the use of the chimney.

I know this is a lot to read but please can someone help me. I really would prefer NOT to spend any more money on this.

I also grew these plants from seed i got from a mate - not sure what they are.

Cheers.

Oh the picture with the fan in it was just a make shift temporary shit thing attached to some holes in the chimney and the last plant photo is of the plants in bad condition this morning. ALSO the chimney is NOT used for anything.

hey i got a few ideas that maybe you can use.
#1 the ballast generates heat, get it out of there if u can.
#2 you can make an exhasut fan at the top to get the hot air out. you can either buy a muffin fan or use a computer fan. for best results i would also add one on top of the reflector.
#3 on the exhaust you can make a home made carbon filter to cover the smell. heres a good one
https://www.rollitup.org/do-yourself/101248-best-diy-ez-walmart-carbon.html

hope this helps

Ah yeah that's what i'm thinking. I have already taken the ballest out so that's sweet. With the chimney it was used for an air intake from the roof and has a smaller one built inside for an out take for a gas heater, but i cant drill into that because the steel is too thick. So fresh cool air comes down it and it seems a bit of a waste to send hot air up there. Yeah i'll try the fan on the light shade i hadent though of that one. Cheers!

putting the fan on top of the reflector with no exhaust would sound like a waste to me. the idea is that the hot air get sucked out while the cool air replaces it. i highly doubt the cool air would be enough to cool off the little space you have. plus it will be more beneficial to the plants. as far as i kno, the exhaust is more important then the intake because exhaust will create a negative pressure that will suck in fresh air from outside the cabinet. maybe you can use the hole you already have for the exhaust? just run a duct to the top of the cabinet to suck the hot air out. or even better run the duct all the way to the reflector and you can do a diy cool tube sort of.

Dont want to put a dampener on things mate, but by the time your plants are in bigger pots you have effectively run out of growspace. Lets say 1ft for your light, 1ft for your pot, only leaving you 1ft of room for your plants. Because of the lack of headroom heat will build up quicker. You gonna need tip top ventilation to succeed. Think you gonna need to go for a cooltube for your light. Then some kind of exhaust fan at the top, with ample venting round bottom of your growing area you will not need an intake fan. As the exhaust fan will draw in fresh air from venting round bottom of grow area.

Unless you are totally sure that the inside of the chimney is spotless do not use it either, unless for venting.

I suggest you read up on Low Stress Training so you can keep plant height to a minimum. Next time choose a growing chamber with more headroom.

i realise this height is pretty unrealistic but it's the only space i've got out of the whole house. Low stress training - this looks great i'm going to give it a show and will probly post pics if this works. But my other thought was to place a metal frame - something like chicken mesh over the top of them when they are about 1 foot high and continue to grow them horizontally ather then vertically, creating a flattened canopy effect. Would this be any good??