There is an upper limit on how much Pex tubing you can use in a radiant heating installation. If the circuit is too long, the solar fluid will cool off before it reaches the end and you will get uneven heating. For standard-sized Pex tubes (half-inch or 5/8-inch internal diameter), the circuit length should not exceed 300 feet – which is conveniently the size of the coil supplied by many manufacturers.
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Before you begin laying Pex tubes into your heating area, you must prepare the ground. The area should be flat and level, with the insulation in place and a vapor barrier under the insulation. If you are going to enclose the Pex tubes in a slab, you can cover the insulation with reinforcing wire or rebar.
Setting up a solar thermal space heating system is only one side of the renewable energy heating coin. The other side is actually delivering the heat the installation generates to your home. Assuming you've chosen an appropriate system for your needs, you have captured the sun's energy and either stored it or have it ready to be dumped straight into the building. What next?
In practical terms, choosing the right size for your solar thermal hot water storage tank and collector array is one of the most important aspects of system planning. Get the wrong sizes and you could be in trouble - too small and your grid-tied bills will be unnecessarily expensive and the system risks overheating; too large and your installation costs will be too high.
Very few solar thermal space heating installations provide 100% of a home's heating requirements year-round, so a grid-tied backup is almost always required. It is obviously a lot more efficient – particularly financially – to use the same heat delivery equipment for both systems wherever possible.
Evacuated Tube and Concentrating Collectors
This is a common question from people who want to retrofit a solar thermal space heating system. The simple answer is "Yes, you can integrate the two systems." The reality of the process is a little more complicated.
Any renewable energy installation is a major project, but one of the simplest questions is often "What equipment do I need?"
Control in a batch installation
If your solar thermal system has no storage, the heat gathered by the collectors goes straight to the ducting. When heat is needed, both systems are switched on, so hot solar fluid circulates to the heat exchanger and the furnace blower distributes the heat around the building.