When I tested my heater, I used a couple of chunks of heater hose, slipped tire valves, the rubber end into the hoses and used gear clamps on them. The other ends were hooked up to the heater. I was able to use a bicycle pump to provide pressure and then immerse the whole thing in water. If you can make a tire the source of your air pressure, you can set the tire for whatever pressure you want and use a similar setup.
