by bobbi
26. January 2009 18:36
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I get a lot of questions about the efficiency of insulated pex pipe. People ask what type of insulated pex is better, how much R-value each brand has, and how to tell if a certain brand of pipe will work for them locally. These are important questions since improper installation techniques can lead to poor efficiency.
Insulated pex is commonly used to transport hot water from outdoor boilers to home systems. Whether the outdoor furnace is fueled by wood, corn, or pellets - that heat needs to be transferred efficiently to the dwellings and shops that it's intended to warm. Insulated pex pipe will have a hard outer shell, some kind of insulative wrap or fill, and two pex lines in the middle which transport hot water to and from the stove. The shell material is commonly plastic corrugated tile pipe. It's purpose is to prevent environmental water, harsh environmental conditions or particles from getting into the system, because that could interrupt the efficiency of the insulation. The heavy duty tiles also prevent the inner insulative barrier from becoming compressed which would also lessen thermo efficiency.
Underground pipes should be well insulated with foam and the feed and return pipes should not be allowed to touch each other. Insulated pex can be buried anywhere from 1.5 feet to 2.5 feet below ground. Some say don’t place the pipe in the ground deeper than 18” to avoid ground water. When installing your insulated pex, seal against water entry where ever possible.
Some types of pex pipe are better able to protect than others. For example, a pex pipe that is insulated by wrapping an insulative blanket around the pipes will lose it's protective quality if any ground water finds it's way into the hard outer shell.
Do your research, there's a lot to know. This is a big investment and you basically get one shot to get it right before winter hits and you're locked in till spring.
Here's a list of links you may find helpful: