Pipe Freezing

When the plumber came to alter some pipework in the central heating, I had anticipated that the whole system would need to be drained, which would have been quite a performance. But, in fact, he used a 'Freeze Master' to freeze the water in the pipes he wanted to work on. The 'Freeze Master' is a portable refrigerator which plugs into the mains and passes a chilled refrigerant through flexible hoses to a Freezing Block attached to the pipe. The machine used had two hoses and two Freezing Blocks. Each hose is, presumably, provided with two bores to accommodate flow and return of the refrigerant.

The photograph below shows two Freezing Blocks secured to the pipe by a G-clamp. The machine comes with a series of reducers to allow smaller diameter pipes to be dealt with.

I'd not seen this technique used before and I thought it was an ingenious application of the properties of water.