#106 – Freeze Machine

by Tom Doty

Some years ago, our service department invested in a freeze machine. For those of you who don’t know what a freeze machine is, it is a Velcro sleeve that wraps around a pipe and has a chart that defines freezing procedures based on water pressure.

For example, if the water pressure is 100 psi, charge the sleeve with a 30 second blast of CO2 initially, followed by 10 second blasts every 30 seconds thereafter to maintain the frozen pipe. This eliminates the need to shut down and drain a system and then refill the system when work is completed. It has worked great, especially for small arm-overs.

Our crew arrived at a job to relocate two sprinkler heads, not knowing at the time it was a tri-water system. At the time, the cost of copper was going through the roof and someone in their infinite wisdom came up with a tri-water system. This system essentially eliminates the need for supply and return lines to the air conditioning by running an extra sprinkler main. With one main being supply and one main being return, the system alternates the sprinkler lines — one from supply and the next from the return. The problem is there are also two shutoffs and the water circulates, which causes the chart that comes with the freeze machine to become obsolete.

Need I state the obvious? The tenant’s office got flooded, we got reamed, and the big mess had to be cleaned up. The popularity of tri-water systems did not last too long as the air conditioning people wanted to use (flammable) rust inhibitors to maintain their units.