About Me

How to Completely Change Your Thoughts About HVAC

Welcome to my blog. My name is Betty, and I recently invested in a new heating and cooling system. It had been years since I had purchased our old system, and my husband was alive then. This was the first time selecting my own system. I did a lot of research and even considered taking our HVAC system off the grid. Now, that my house is the perfect temperature all the time, I'm ready to try something else -- so I decided to start a blog. Here, I am going to post a range of blogs on HVAC related issues as well as home repairs and other topics. I hope that you like it.




How to Completely Change Your Thoughts About HVAC

The Heat Is On: Should You Choose An Active Or Passive Solar Hot Water System?

by Eva Fisher

When shopping for a new solar hot water system, however, you shouldn't just plump for the first system that catches your eye. You have a number of factors to take into account before deciding which system is best for you, and one of the key choices you'll have to make is whether to opt for an active or passive system. These different types of system function in drastically different ways, and how well they'll perform for you depends largely on your needs and your local climate.

Passive systems

Passive solar hot water systems have very few moving parts and are not powered, instead relying on heat generated by the sun to circulate the heating fluids through a physical process called heat convection. The simplicity of these systems means that they are generally the most inexpensive options on the market, and means the systems require little or no maintenance. If they are placed correctly in a sufficiently sunny area, passive systems can provide for your heating needs without requiring external power to remain functional.

However, passive systems do not transfer heat as quickly and efficiently as active systems, and generally speaking a passive system will need to be quite extensive, with large areas of solar panel coverage, before they become cost-effective. They also have less flexibility when it comes to providing consistent hot water at irregular times. As such passive systems are generally best used on larger buildings, or in particular hot climates. 

If you do choose to install a passive system in a hot area, be sure to use an efficient heating fluid formulated to work under particularly high temperatures -- unsuitable heating fluids can boil and denature in particularly hot temperatures, reducing efficiency and damaging the internal parts of a system.

Active systems

Active systems differ from passive systems in that they utilise a powered pump to move water and/or heating fluid to where it is needed most. These systems provide a great deal more flexibility and control than passive ones, and will generally provide hot water on demand much more quickly. In addition, the power of the pump means that hot water tanks can be placed lower than the solar panels, even as low as ground level. This reduces installation costs and makes hiding your tank from scrap metal thieves much easier. Because active solar hot water systems do not use heat convection to pump water, they subsequently lose less heat, increasing efficiency.

However, the increased complexity of these systems naturally entails a significantly increased cost, particularly if you require a large and powerful pump to provide hot water coverage to a large building or complex. Active hot water systems will also require regular maintenance to retain full functionality, and are more prone to pressure cracks and leaks than passive systems, particularly around the head of the pump.