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.
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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.
Drainback Solar Thermal System Heat Exchangers
Like any closed-loop installation, drainback solar hot water systems use a heat exchanger to pass energy from the solar fluid to the domestic water supply. However, drainback setups include a third, specialized tank – the drainback tank – which holds all the solar fluid when the system is idle. This fluid can still be very hot when circulation stops, so it makes sense to have a means of passing that energy to the domestic supply rather than waste it.
Integral Collector Storage Solar Thermal System Layout
Integral collector storage (ICS) solar hot water systems are remarkably simple and cheap when compared to the other types. They don't use pumps, they don't need controllers, they use only one tank and they require very few extra components beyond a big water tank, some pipes and a pile of insulation materials.
Thermosiphon Solar Thermal System Basics
Probably the least popular solar hot water installation, thermosiphon systems come in two types – direct and indirect – and are passive. They use no pumps but instead rely on the fact that hot fluids rise to provide circulation.
Flooded Open-Loop Solar Thermal Systems
The simplest of the active solar hot water installation, flooded open-loop systems have water in the pipes, collector array and tank at all times. They are more complex than a passive system because they use a pump and controller, but compared to other active systems they are cheap and easy to install and maintain.
Recirculation Solar Thermal Systems
A recirculation solar hot water system is almost exactly the same as a flooded open-loop installation. However, it has one significant advantage: in times of very cold weather, it can recirculate warm water from the storage tank through the pipes and collector array to prevent freeze damage.
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