Much like seasonal swimming pools, spas and hot tubs can profit enormously from solar heating systems. This is especially true if you're installing a solar thermal system for your domestic hot water supply or space heating because the tub or spa can act as a shunt load, using excess output from the household system.
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.
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.
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.
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.
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.
A check valve is a simple device that only allows liquids to flow through it in one direction. These valves have an arrow marked on the outside to show the allowed flow direction. Two different types are used in solar thermal installations: "spring" and "swing" check valves.
All modern solar thermal systems use both vents and vacuum breakers. Vents are used to allow air to escape from a circuit that holds fluid and vacuum breakers do the opposite, letting air in when the internal pressure falls too low.
When it comes to your local climate, there are some factors that can seriously affect your choice of collector type. The worst non-catastrophic climatic event for solar thermal installations is, without any doubt, snow. It's the worst because, unlike rain or total cloud cover, it can physically pile up on top of the collector and block out the sun's light.
Despite all the advances of modern technology, the best solar fluid for use in a solar thermal installation is water. It retains and transfers heat better than any other liquid in the world. However, it has one major drawback: it freezes easily.
The industry standard for solar fluid is a mix of propylene glycol and water. It's non-toxic, biodegradable and relatively stable. However, you should always mix as much water as possible with your choice of glycol product, as simple water is the ideal solar fluid.
