Hay Jack,
Forced air was probably a bad choice of words.
I have one of these for each of the rooms, plumbed in parallel with the the tubing under the floor for each unit. Each one has a sensor to turn on the fan when the water warms up, not sure if I'll use it or a switch or both. I was going to use heater cores and build a box with a fan, but I got such a good deal on these I couldn't turn it down. I got 5 of these and one that is bigger with two fans for something like $65.
This is the foot heater (lived here all my life, I HATE cold feet)
This is the back side of the foot heater.
I keep reading about how noisy and stinky these things are. I can hardly tell it's running inside the bus, and I don't even have the wall in yet. When it's on low it makes less noise than an RV furnace.
On start up there is a few wisps of whitish smoke. It does make some noise when running on high, but I've heard high dollar RV's water heaters much noisier. Pretty much all of the noise is out the exhaust, and mine goes out the top, so it's 6 feet above your head.
Dick