[NiHaoMike]

I actually used an incandescent lamp to warm various parts of the plumbing during the second and third vacuum pull. I actually have a sight glass with moisture indicator, which indicated that it was dry on the first vacuum pull, without using the lamp. Therefore, the pump I used was sufficient for my application, but then again, it is not particularly demanding since I can use a lamp to help remove the last traces of moisture. Setting up a heat pump on a cold day, on the other hand, would demand a very good pump system. That's where an ion pump or diffusion pump comes into play.

Has anyone thought about building a precision vacuum gauge? Take two pieces of glass tubing, fill one with vacuum pump oil, and cap off the end so there's no trapped air. Then take a piece of vacuum hose, connect one end to the glass tube filled with oil, fill it with oil as well, and connect the other end to the other glass tube. Mount it on a stand in a U configuration and connect the remaining open end to the vacuum pump. If the density of the oil is known, the vacuum level can be calculated by measuring the difference in level in the tubes and translating it into pressure.