■ Hydronics This large feeder was installed in a central biomass heating plant in northern British Columbia.
The most common, and arguably most effective, method of preventing pipes from freezing is with the use of glycol. By Roy Collver It is a well-known fact that water expands when it freezes. Every component within a hydronic system is subject to rupture or destruction as a result of this fact. It is sobering to think of the force required to blow apart a malleable iron pipe fitting, cast iron pump, or piece of schedule 40 steel pipe. All of which I have seen firsthand. We live in cold country where accidental freeze-up of buildings is possible everywhere, even on the balmy West coast. How do we prevent destructive freezing from happening?
Strategically chosen There are four basic principles when it comes to freeze protection strategies. The first involves the prevention of all hydronic components from reaching temperatures below freezing. To ensure this, every
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Plumbing & HVAC – September 2021
component of the system must be installed within a conditioned space and sufficient backup plans. Equipment must be in place to ensure the space never goes below freezing in the coldest weather during extended power outage situations or mechanical breakdowns. The second strategy is to drain all the water from the system before any type of freezing occurs. This is a common strategy with some solar thermal system outdoor components, but it requires careful piping design, equipment, and controls to ensure everything will drain out completely. Keeping the water temperature above freezing and moving it fast enough so it will not freeze in cold sections of piping is the third option for contractors. This must be done even when space heating is not required. Control strategies for opening all zone valves
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