Risk of freezing HDPE aerial pipe
asked 9 December 2016 asked by cd2016 (360 points)
Hi As long as you keep the water circulating, there should be no problem.
Hi You can heat it externally using thermal tape or cables available through different distributors.
Given the length, I would say you run the risk of freezing even with a good constant flow through the pipe. Where are you located and at what altitude? I am not even sure whether insulation or external heating is going to be that effective. And there is a cost to heating the pipe.
With that kind of extension, insulation is imperative. The flow rate and the temperature of the water will be factors in determining the thickness of the insulation and heating cable. Also, you will want to think about what happens if there is a power outage. Can the flow be stopped and for how long?
I agree with the previous comments. Even with a travel time of an hour and a half at 5.5 m3/h, if the temperature of the water is already low (less than 10 °C) and the outside temperature is in the negative digits (-10 °C overnight, tube not exposed to sun in the daytime), there is a danger of freezing. In practice, the fact that the speed of the water is faster in the center than along the pipe walls means ice can form more quickly. Wrapping your pipe with a heating cable inside a thermal covering, i.e., the same principle as an electric blanket, might not be that expensive, especially in the main exposed section of the pipe. Another idea might be a motorized valve that can boost the flow rate at regular intervals, as long as the water isn't too cold to begin with. But you would have to consider several technical parameters to make sure it was viable, such as the density and thermal conductivity of the HDPE, the temperature of the water at the source, length of pipe, etc.)