You actually made my point for me. I was going to use the pot and lid example. Boil a pot with no lid there's no pressure. Add a lid(resistance to flow) and now you are making pressure. I think I made it clear that heat produces vapour and with a resistance more vapour(aka more heat) will equal more pressure.
Also your example of the pic of the guy blowing steam is a perfect example of bernoullis principle. You have high velocity and no pressure. I also pointed out if you have pressure it will be on the boiler side just like your last post pointed out so I'm not really sure where your confusion is coming from.
You don't have to explain you aren't trying to start a fight, I know you're not BW. I'm a tradesmen and had to learn all this in college which is why I thought I would try to help people have a real understanding for what is happening in their system. I wasn't trying to crap on you, you are one of good ones around here in my books.