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Heating with a Wood Furnace
There are both indoor and outdoor wood boilers and furnaces. Outdoor boilers are really big wood stoves with a tank of antifreeze solution or water surrounding them. The burning wood emits heat to the fluid, giving hot water and energy to warm the house. The boiler temperature is regulated by a home control system. Most include an alarm for re-stocking. Furnaces provide warm air; they come as indoor units only.
Photovoltaic System Grounding
Grounding is used to dissipate electrical energy safely when faults occur. This is the third pin on your extension cord plug which allows electricity to flow when system insulation fails.
Basic Principles of Solar Thermal Systems
As soon as you start looking into a solar thermal installation, you will run into certain terms and principles that may be unfamiliar. It is essential that you understand these ideas, so that you can see what is needed and make intelligent decisions when offered choices by professional installers.
Pressurized Solar Thermal System Pumps
One of the advantages of a pressurized solar hot water system is that the solar loop is always full. This means that the pump has no static head pressure to overcome (just friction head), so low-head, slow-starting pumps can be used effectively. And those pumps can be run on power from a PV array, eliminating your grid-tied power costs for operation.
What are Drainback Solar Thermal Systems?
Drainback solar hot water systems are not as flexible as pressurized systems, but still work very well in both residential and business applications. They are very efficient if they are planned and installed carefully.
Drainback Solar Thermal System Pros and Cons
These systems have many advantages:
- They can use simple water as a solar fluid for lower cost.
- They are very efficient if they are planned and installed properly.
- They are ideal where the installation will lie idle for extended periods.
- Since the system empties when it switches off, the solar fluid has a long life.
It's also important to consider these disadvantages:
Drainback Solar Thermal System Tanks
Drainback installations use three tanks to heat the domestic water supply. The two main tanks are just like those used in pressurized solar thermal systems. However, the third is specialised – the drainback tank, which is installed on the solar loop.
The two main tanks are installed in standard fashion: the one heated by solar energy is piped in series before the backup grid-tied tank, so that the sun-heated supply is topped up with heat in the second tank if necessary.
Drainback Solar System Pumps
Unlike pressurized installations, drainback solar hot water systems have a fair amount of head to overcome before they start operating properly. Consequently, they need more powerful pumps. The choice of pump is absolutely critical to the system.