Solar Water Heater Regular Inspection Checks: Knowing When to Drain

December 13, 2018

Sustainable and energy-efficient by design, solar water heaters deliver toasty warm water straight to your waiting sink taps and shower heads. It’s something of a miracle, the technology that makes this sun-powered action possible. Only, like any other piece of technology, efficiency drops do develop. To stop this energy leeching effect, take the initiative. Carry out a regularly scheduled inspection. Now, studying the results, is a system flush imminent?

On Sampling the Water

Yes, the regularly scheduled inspection has concluded. Is it time to drain the solar water heater? Well, the water isn’t clear, that’s the first discernible problem. If the particles are found to be hard water, that’s not so bad. Many regions have problems with minerals, which dissolve into the local water table. Filters help, as do descaling compounds. For your purposes, though, the sediment is already trapped in the system. Furthermore, the minerals are accumulating on exposed surfaces. This scaling effect undermines solar efficiency. And what if the water-suspended particles turn out to be rust coloured? Corroded parts develop due to galvanic reactions. Perhaps, with the corrosive build-up flowing, the sacrificial anode has collapsed? Whatever the reason, the system must be drained before the corrosion causes permanent damage.

For Heat Transfer Fluids

In the above example, the sediment and other particulate loads were acting as a sort of interference layer. They hampered the efficiency rating of a normally efficient solar water heater. What if the device uses heat exchanger technology? Loaded with glycol, sediment is still floating suspended in the water? After all, the minerals are entering the water from outside the property. They’re soluble, so they’re dissolving into the water as they leave the soil. When this effect impacts a heat exchanger, expect the mineral scale to form on the surface of the heat exchanger, so appliance efficiency again suffers. Calcium deposits, perhaps galvanic corrosion, too, can form on distribution piping, heat exchanger surfaces, in the collector section, and in other key fluid-carrying sections.

There’s no getting rid of such system contaminants. If the water was too acidic, a alkalinity would neutralize the caustic chemicals. For solid particulates, there’s just no getting around the fact: those free-floating solids cause scaly calcium-based films and corrosive patches to form. Left like this, solar water heaters can’t operate efficiently. If the water sample dries into a powdery deposit, drain the equipment. If it’s running cool, and the system components check out, drain the system. Replace the sacrificial anode, too. To drain a solar water heater, turn off the water supply, remove the electricity supply, or gas, and attach a hose to the drain valve. Open the drain valve.

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