Raises the temperature in my garage by about 10degs.
The double garage it's in was warmed up quickly enough to a point where I can work in just a T shirt even though the outside temperature was 3-4 *C.
How much gas it uses I can't comment on yet.
Have the heater up and running in my garage and it's brilliant, only need it on for a short time to warm the garage up, would recommend it to anyone with a work shop or garage.
works really well .. used it places where we are installing new heating systems to keep warm enough to work comfortably.
small enough to keep in the van and big enough heat big areas
Big garage. Little heater but big output just the job for these cold days and nights. Only time will tell how much gas is used, but seems reasonable so far.