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Converting your attic

It can be hard to find the space to store all of the items that we need, so it's important to make the most of all the space in your house. If you have a dusty loft or attic with a collection of messy boxes, sometimes the answer can be to convert the attic into a proper storage area with lighting and storage cabinets for the items that you really need. You might be surprised what you find lurking up there when you actually clean it up and organise the area properly! Read on to learn more about attic conversions.

Converting your attic

Selecting the Right Circulating Pump for your Solar Water Heating System

by Guillermo Caballero

Circulating pumps are used in a variety of applications, including to circulate water in swimming pools, hot tubs, aquariums, spas and other hot water systems. A typical electric circulating pump consists of a motor and impeller hosted in special impeller housing. The motor rotates the impeller which then draws liquid up through centrifugal forces. To work, the impeller must always be covered with fluid as these pumps cannot suck liquid into the pump. As such, the pump is usually installed at a point lower than the maximum water level for proper working.

If you're selecting a circulating pump for a solar heating systems, there are a few important factors to consider, and these are given below:

1. Pump materials

Cast iron and steel pumps are prone to corrosion, because iron rusts when exposed to air and water. More affordable circulating pumps are usually made of iron impeller housing. In order to use these, they must be installed in closed-loop systems in which only distilled/unoxygenated water flows. For open/portable loops, corrosion is inevitable, resulting in partial or total obstruction of water flow.

Residential water heating loops should instead have plastic, stainless steel or bronze impellers and impeller housings. These are resistant to corrosion, and they are also recommended for use in all drain-back systems where distilled water is not used in the collector loop. Of these, bronze and stainless steel are most commonly used, but the rise in cost of copper make the latter more attractive to homeowners.

2. Pump head resistance

There are two types of head a circulating pump works against:

  • Atmospheric head – height different between natural level of liquid (with pump off) and level to which the pump must push the liquid when on. For solar-powered drain-back water heating systems, the circulating pump needs to push water to the top of the collectors. For plumbing circuits however, there is no atmospheric head if the circuit is full of fluid at all times.
  • Friction head – this is the flow resistance created by fluid contact with the piping material (walls), and it increases with increased length, smaller diameter, directional changes and increased flow rate. However, this isn't a major concern except for small piping runs exceeding 100 feet.

3. Pump flow rates

Typically, solar collector loops can operate efficiently at different flow rates. However, a larger circulating pump costs more in operating and initial costs, and yet it may not be necessary for your use. Choosing a pump that's too small will cause the entire system to fail. You can use manufacturer's specifications to get the suggested flow rates in order to ensure that you get the right size for efficient performance.

4. Power source: AC vs. DC

There are both AC and DC pumps on the market, but you have fewer choices with the latter than the former. An AC pump has the advantage of unlimited energy supply provided the utility grid is also reliable. However, DC pumps can be directly connected to photovoltaic modules which makes your solar water heater able to run independent of the grid.

DC pumps are generally more efficient for solar water heater circulating pumps. However, they are also noisier and more expensive, since DC pumps with high head drain-backs are rarer than their AC equivalents. If you can shoulder the extra cost, they are a better fit with most solar water heating systems.

When you're ready to get your pump installed, don't hesitate to reach out to a local electrician, such as Ln Electric Motors Limited

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