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Direct Solar Water Heating System
Find out how to put together a simple and cost effective
direct solar water heating system
There are two main types of water heating system - direct and indirect. In an
indirect system fluid such as anti-freeze is heated and then passed through a
heat exchanger (1) fitted to the water tank. The heat from the fluid raises the
temperature of the water in the tank, and the water in the tank cools the fluid
ready to be passed around the system again for further heating. The less
complicated option is direct heating in which the water to be heated is itself
passed around the system. Such a system can be put together by anyone with
an intermediate level of DIY proficiency.
In this article we will look at a very simple direct solar water heating system
which can be built using easy to find plumbing and automotive supplies, and a
small pump (2).
Direct Water Heating Schematic
Pictured below is a schematic diagram of a typical simple direct solar water
heating system.
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Direct Solar Water Heating System - ...
Connecting everything up just requires copper pipe and either solder (or more
simply) compression joints. This system can be used year 'round with
evacuated tubes (3), and will work well for 2-3 seasons of the year with a flat
panel solar collector - e.g. a radiator painted black.
The only tricky part to implement is sourcing and connecting in a suitable pump
and controller (to run the pump when the solar panel is hotter than the water
in the tank). For the pump controller we of course recommend our very own
solar water heating pump controller (4). For the pump we recommend the
following 12 VDC high temperature water pump.
This pump is brushless so it will be maintenance free and long lasting. It can
operate from 9-14 VDC and can be powered directly from a PV solar panel (5)
(10 Watt). It is rated at around 7 Watts (0.55 Amps @ 12VDC), it can pump
water up to temperatures of 120 Celcius, has a flow rate adjustable from 1-7
litres per minute, and it is virtually silent in operation. The pump creates a
head of 2 metres, however do not forget that in this design of solar water
heating system this is not relevant since the water moving downwards pulls the
water going upwards up by the syphon effect.
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Direct Solar Water Heating System - ...
This pump is available for less than £25 plus £2.99 postage. Click here to buy
this solar pump now (6).
The pump has a 14.1mm inlet and a 10mm outlet diameter. In order to connect
this to standard 10mm or 15mm copper piping it is recommended to use auto
radiator hose. It is also possible to use flexible tap connectors available from
DIY stores and plumbers merchants. It is usually recommended to use 10mm
rather than 15mm since the narrower pipe is easier to work with and cheaper
per metre length.
The vendor of the pump discussed in this article is also willing to put together a
full connecting kit which is offered for sale in 10mm or 15mm versions for
£4.50 including postage if purchased at the same time as the pump.
Web Link References
Article from
Published: 24th September 2014
© REUK 2015
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