New Polar FT7 HRM and disappointing caloric count

I am with you Chainsaw Flower.

I just got the FT7 specifically to track calories. My calorie count was drastically lower than what the treadmill said.

Here is my counter argument to everyone that says that the FT7 is accurate and the machine is not.

My FT7 workout heart rate matches the machine perfectly-calorie count 50% less than the treadmill in an hour (I get it, everyone thinks the treadmill numbers are high)

HERE IS MY CONCERN
Workout buddy has the FT80. He does a workout on the same treadmill and his calorie count is < 5 calories off.
He is a different age, height, weight than me...but the treadmill was no where near as generous to him regarding his calorie burn vs his FT80

Soon he and I will switch watches (and user info) to see if the disparity is in the machine or the watch.

I've noticed something similar with mine, and then I realized that the machine displays my HR based on my monitor (I guess it's compatible with Polar so acts as a receiver). Even though the heart rates were identical throughout my workout, the calories burned would vary drastically. On the elliptical today for 20 minutes, the machine said I burned 57 cal and my Polar watch said 107. However, on the bike yesterday, the bike put me at 300cal and my watch at only 200.

It's really frustrating! On instagram, I like to search #HRM to see what other people are doing and I see loads of people with their monitors displaying 800 cal burned in a 1 hour workout, and I'm over here struggling to reach 400! I wish I knew how to up the burn like that, I don't slack off at the gym so it's really upsetting to work hard for an hour and see I only burned 300 calories.

I noticed the same problem with my new Polar FT60. I upgraded from the F4 and realized the new monitor even gives me a lower calorie burn than my old HRM. How can this be? They are manufactured by the same company!