what kind of portable heat can one use in tent for 3-5hrs?

The portable heat unit doesn't have to run all night. it should last long enough to warm 2 person in winter tent stay warm before falling sleep.

I am not referring to any kerosene/ gas heater since they produce CO in enclosed space.

Little buddy, google it.

Be careful! You could "fall asleep" not not wake up again esp if the tent is pretty air tight.

Dave

ok. I found this coleman flameless heater for the nylon temt.

http://www.cabelas.com/cabelas/en/templa...&hasJS=true

It doesn't produce any flame.

I'm assuming that there would be some kind of ventilation in a tent. Also it has an auto shut off if the oxyegn level drops below a certain percentage. They are actually designed to by used in tents, cars, indoors.

For what its worth anyway.

Here's a link.

http://www.mrheater.com/

Cabela's has a good price.

http://www.cabelas.com/prod-1/0005701514531a.shtml

BTW I'm not affliated.