Common hot and chilled water piping - long runs 2

[l3oertjie]

Dear fellows,

I am designing a system with common hot and chilled water piping with seasonal changeover. The pipe runs are quite long - about 60m (exposed to ambient conditions). Does anyone know of any special precautions one should take except for linear expansion and proper thermal insulation?

Water conditions are as follows: 6°C / 11°C chilled water and 40°C and 45°C Hot water. Pipe size 150mm. Velocity: 1.29m/s.

Ambient conditions range from -5°C to 35°C. Typical South African winter and summer extremes in Johannesburg.

Your input would be much appreciated.

Regards,

Andre Burger

 

[MarauderX]

You may want to put heat tracing on the piping to prevent it from freezing. If you have a condition where the water stops flowing in -5C it will eventually freeze... prevent that from happening overnight by adding the heat tape inside the insulation and a simple temperature sensor.

http://www.vanderweil.com

 

[l3oertjie]

Thank you for your input MarauderX, in South Africa the ambient temperatures rarely reach those low values and often do not last that long - hence the reason why we sometimes forget to include heat tracing. I will however consider the option as we are running water at pretty low velocities as well.... Thanks again.

 

[marcoh]

Boertjie, Need to ensure the typical piing issues, air vents at high points, right thickness insulation, vapour barrier, sheathing etc, and should probably use a preinusulated piping system.

If you have duty/standby pumps it should be enough to circulate the water when to prevent freezing when it get too cold. Had someone tell me thats all they do for freeze protection in Moscow where it get to be -40!