Heat Pumps
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How Does A Heat Pump Work?

Heat pumps operate on very similar principle to a fridge. Refrigerant flows through connected indoor and outdoor coils. In heating mode, as the liquid refrigerant flows to the outdoor coil, it passes through an expansion valve that creates rapid expansion of the liquid, causing it to become a gas. This results in very rapid cooling of the refrigerant. Then as it flows through the outdoor coil, it is able to absorb heat energy from the air. Before it flows through the indoor coil, it passes through a compressor where the gas is compressed, increasing both the pressure and the temperature. As it moves through the indoor coils, the gas condenses, releasing latent heat.

Heat pumps offer a distinct advantage over conventional heating equipment in terms of CO2  emissions.              How a heat pump cycle works

Heat Pumps vs Solar Panels

Heat pump: advantages

  • Easy installation: The installation of a heat pump doesn’t require intricate plumbing work and is fairly easy to install, on both a commercial and residential level.

  • Minimum space requirements: A heat pump needn’t be installed on a roof, and can be installed outdoors.
    Hot water 24/7: Because a heat pump relies on electricity, it can provide hot water 24/7 when there is dependable electricity supply.

    Heat pumps: disadvantages

  • Heat pump manufacturers do not warrant their systems if the hardness of the water is higher than a certain level. Hard water (water with high levels of calcium carbonate) needs to be treated with a water softening plant, resulting in high cost implications.

  • Heat pumps may require more maintenance, due to constant moving parts that needs to be replaced from time to time. Maintenance on a heat pump also requires the skills of a plumber, electrician or air conditioner technician. A heat pump has a compressor (like a fridge), a fan and a water pump to cycle water to the geyser (where a separate geyser is used).

  • The lifecycle of a heat pump is typically less than solar heaters.

  • Heat pumps are completely dependent on electricity to generate hot water.

  • When installing a heat pump externally at coastal areas one should be aware of prevailing wind conditions potentially bringing salt into the pump.

  • Heat pumps make a sound similar to the external air-con units. They tend to operate after hot water has been consumed (at night, early in the morning).

    Heat pumps vs solar panels

    Solar water heater: advantages

    A roof mounted solar water heater doesn’t rely on electricity to provide hot water when the sun is shining. Most solar systems have a backup element, which means that your household will always have hot water regardless of the weather.

    Solar water heater may come with longer factory warranty

    The lifecycle of a solar water heater is regarded as longer than that of a heat pump.
    Can produce higher water temperatures than heat pumps and could even bring the water to boiling point.

    Solar water heater: disadvantages

    A solar water heater works optimally when the sun shines, if it is overcast, the back-up element kicks in to compensate for the lack of solar energy.

    SWH panels are susceptible to airborne dirt build up from dust, pollution, rain and salt sea spray. These can reduce the effectiveness of the solar radiation collection. Solar tubes may require occasional cleaning for optimal efficiency

    Orientation and positioning of the SWH panels is imperative to maximize the solar radiation collection capabilities.

Closed Loop Active Systems

Closed loop active systems employ heat exchangers that circulate heat exchange fluids through the panels and feed pipes. The term “closed-loop” refers to the solar exchange fluid being closed-off from the external atmosphere or isolated from the potable water. In a closed-loop system the heated solar fluid is pumped through the solar collectors. The solar fluid flows through a copper or stainless steel heat exchanger located near the solar storage tank. The heat from the fluid then transfers to the potable water within the solar storage tank. Another small circulator pump may be used to circulate the water through the potable side of the heat exchanger.

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