Winter is coming! - Need help increasing temp during lights out

Hey guys,

During lights out my temps are falling to 17c

I could simply close the window but that's my only source of fresh air and the window is also knackered, as in, it won't close completely anyway.

Can anyone recommend a means of heating my grow room. Looking for someone who's got some experience to avoid any pitfalls.

I was thinking of just buying a fan heater and sticking it in-front of the intake fan.

http://www.ces.purdue.edu/extmedia/ae/ae-89.html i use water for heat storage let my room heat when the lights are on than when the lights are off water release heat back into my room ......

Impressive. I would consider that option if I had a permanent grow room. I'm currently using a tent setup, so not much room inside

Simple, get another tent, run opposite 12/12 cycles and vent each tent into the other.

Another light would probably be cheaper than the space heater to run.

Wet