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Active and Passive Solar Space Heating
In most parts of the world, space heating systems are installed in every home. They provide warmth and comfort during the colder part of the year. Unfortunately, the vast majority of these systems rely on grid-tied, non-renewable power sources to provide that heat. In a bid to reduce our environmental impact – not to mention our operating costs – we can use the sun's power to provide space heating.
Types of Solar Thermal System
Before you decide which kind of system you're going to install, it's important to understand the basic terms used to describe them.
Open and Closed Loops
An open loop or direct system is the simplest: the domestic water actually enters the solar collectors and is heated by them before heading back to the storage tank.
Solar Thermal Space Heating Basics
Like solar thermal hot water installations, there are many different options available for space heating. Before you consider them and work out which is best for you, it is important to be aware of the limitations and pre-installation suggestions outlined below.
Pressurized Solar Thermal System Basics
A pressurized system should really be referred to as a "closed-loop pressurized antifreeze solar thermal system" – the two-word version is much simpler and more common! Pressurized systems are the most flexible type of solar hot water installation and, consequently, are the most common worldwide.
Pressurized Solar Thermal System Layout
A pressurized solar hot water system almost always follows a standard layout, which is one of the reasons most manufacturers are able to offer simplified kits for residential installations.
Pressurized Solar Thermal System Considerations
If you think a pressurized solar hot water system fits your needs, you must consider a variety of rules, limitations and requirements, as outlined below.
Array and pipe mounting
Collector arrays should be mounted so that there's a slight slope towards the return inlet, where the solar fluid enters, which should also have a drain for maintenance.
Pressurized Solar Thermal System Pros and Cons
These systems have many advantages:
Pressurized Solar Thermal System Thermosiphoning
Pressurized solar hot water installations have a closed solar fluid loop that is always full of liquid. If the collectors get colder than the storage tank and are situated above the tank (as is usually the case), thermosiphoning can occur.
Pressure Concerns in Pressurized Solar Thermal Systems
As the name suggests, a pressurized solar thermal system operates under pressure. In particular, the solar fluid circuit is always under a certain amount of pressure, which can vary enormously depending on the local climate and a variety of other factors. It is vital to understand the effects of pressure and how the system is managed to avoid catastrophic events.