OK. I have hung the water heater hose from the engine room ceiling. I am
still worried about trapped air but just discovered Grainger part # 4A820.
It is a float type automatic air vent made specifically for removing air
from hot water heating systems. It vents air until if fills with water.
Says it is glycol compatible, 240F max working temperature and works to 150
PSI. The vent can be sealed with a little screw so once the system is
purged I can seal it off and it is only 3" high. Looks like the perfect
solution. .
--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com