Hawkbo: Grape God Auto

Autos are just starting to flower the photos are dying for some bigger pots. I've been trying to bring up the overall plant health in general since moving everything to a basement the temps are a little lower than ideal. I had a space heater delivered today and monitored the temps but they only went up to around 78°f I want it to be atleast 82°f ideally 85. The heater uses 1500 watt and only increased it about 2 or 3°. I dont think it's worth the extra cost for such little boost. I'm thinking about returning the heater and throwing a 1000w hps in one of the other tents and see if that will raise it anymore. Especially with LED and co2 higher temps would be very beneficial in veg and early flower but the room is so big its gunna be tough to pull off without killing me on electric costs. Any suggestions are welcome. I know this room does decent in flower but I havnt done much veg work down here and I'll have some autos growing this round so it's important I get it up.