I’ve always disliked the MityVac hand pump, but it was all we could find at the time. Before that we used a very expensive siphon pump that we sourced from a steam fitter catalog. About a year ago, Eldon told me about a garden variety siphon mixer that he had used to evacuate his system. I bought one and have been experimenting with it. I consistently get vacuums at 29″ in just a few minutes using this pump and city water pressure.
The Hozon Brass Siphon Mixer is idea for this use if you make a few modifications. I used compression fittings to attach the rigid plastic hose for an airtight seal. I also used a large throat ball valve to increase flow at siphon. The 3′ of garden hose at the end increases the vacuum by a few inches by not letting air back into the pump. On a tall roof, I used a long garden hose as a secondary siphon to pull the water back down to ground level thereby increasing the relative pressure at the siphon mixer.
The Hozon Siphon MIxer is available at
This is so much easier than the hand pump. Drawing down my empty two Cricket system to 29″HG took only 10 minutes. After filling the system with water to the correct level it took only 1 minute to draw the cold system down to the point that the collectors started pumping.