| RSS Web Feed for Renewable Energy UK |  | REUK Shop | Directory | Bookmark Site | About Us  

Simple Solar Water Preheating System



Simple Solar Water Preheating System

Use solar power to pre-heat water and reduce electricity/gas consumption

solar | heating | water
Printer Friendly Version Print Article     

There are many different solar water heating systems possible, many of which are described in the REUK.co.uk website (links to related articles are provided throughout this article). Almost all new homes and many older homes now do not have a hot water cylinder, and so short of installing one, there is almost no way to set up an economical direct solar hot water system.

Here we will present a very simple method to preheat water before it reaches a tankless boiler. A combi or condensing boiler is fed directly with water from the mains, arriving typically at a temperature of below 10 degrees Celcius. Every degree we can preheat the water before it enters the boiler saves the gas or electricity required to raise its temperature by that degree.

Solar Water Preheater

In order to make a solar water preheater all that is required is a watertight tank or container, and a simple solar collector - for examples see these articles: DIY Solar Water Heating Prototype, Simple Solar Water Heating, Build a Concentrated Solar Water Heater, Evacuated Tube Solar Water Heating, and DIY Solar Water Heating.

Simple solar water preheater system diagram

Pictured above is a schematic for the simple solar water preheating system. (Note that the solar collected must be lower than the storage tank for this system to work.) When the hot tap is turned off, water circulates from the water storage tank around the solar collector and back into the water storage tank thanks to the Thermosyphon effect. No circulation pump is required as hot water rises (or to be more accurate: cold water sinks).

The colder water in the storage tank drops down to enter the base of the solar collector and is heated by the sun. As the heavier colder water in the storage tank continues to try to get to the lowest point of the system, the lighter hotter water is pushed up out of the solar collector and back into the top of the water storage tank replacing exactly the water leaving the bottom.
Convection currents of water in an insulated cylinder - stratification

This circulation of water results in stratification of the water in the storage tank which means to say that there is a layer of hot water sitting on top of a layer of colder water - see the image above for typical convection currents in water in an insulated hot water cylinder. When the hot tap is turned on, preheated water from the top of the storage tank feeds through the boiler (where it is further heated or mixed with cold water if necessary) and comes out of the hot water tap. At the same time cold mains water enters the top of the water storage tank sinking quickly to the bottom and completing the cycle.

On a cold day and cloudy day - i.e. colder than the arriving mains water - the cold water in the tank and collector will just sit there not circulating, and so mains water will effectively be fed directly into the boiler. All connecting pipes and the storage tank must be well insulated as must the solar collector to ensure that nothing freezes up.

See also our article on the Solar Bread Box Batch Heater.
Article Last Modified: 14:47, 7th Oct 2009

Comment on this Article

If you have any comments on this article, please email them to neil@reuk.co.uk.


Recommended Related Articles

People who read this article also enjoyed the following articles:

DIY Solar Water Heating Prototype
Follow the construction of a successful DIY solar water heating prototype
Article Last Modified: 15:16, 19th Aug 2008
solar | heating | water

Solar Storage Combi Boiler Pre Heater
Use solar power to pre-heat water and reduce electricity/gas consumption
Article Last Modified: 10:46, 26th Apr 2010
solar | heating | water | shopping

Build a Concentrated Solar Water Heater
Plans for building a cheap advanced solar water heating system
Article Last Modified: 07:54, 8th Apr 2010
heating | solar | water

Low Carbon Buildings Programme
Grants available for capital costs of microgeneration projects
Article Last Modified: 14:28, 6th Mar 2007
carbon | energy efficiency | general

DIY Solar Water Heating
Build Your Own DIY Solar Water Heating Panel
Article Last Modified: 15:37, 21st Apr 2006
heating | solar

Simple Solar Water Heating
Make a simple solar water heater with easy to find materials
Article Last Modified: 13:17, 30th Jun 2008
heating | solar | water

Test a Concentrated Solar Heater Design
Test results for a scaled down concentrated solar water heating parabolic trough
Article Last Modified: 10:14, 12th Apr 2007
heating | solar | water

Solar Bread Box Batch Heater
Find out how to put together the simplest kind of solar water pre-heater
Article Last Modified: 11:52, 16th Sep 2008
solar | water | heating

Using The LM317T With LED Lighting
Use an LM317T to regulate the current in LED lighting projects
Article Last Modified: 12:47, 12th Mar 2008
lighting | electric circuit

Using The LM317T To Regulate Voltage
Use an LM317T to regulate voltage in renewable energy projects
Article Last Modified: 15:04, 7th Mar 2008
electric circuit | electronics

© 2006-2010 REUK - All Rights Reserved
Page Last Updated on 2nd September 2010 at 02:24:32pm

Latest
Articles


Eco Kettle 2 Chrome
Save electricity with an efficient eco kettle - new improved chrome version
energy efficiency
15:25, 18th Aug 2010

OWL CM119 Wireless Energy Monitor
Find out more about the new OWL CM119 wireless electricity monitor
shopping
15:23, 18th Aug 2010

KC7783R PIR Module
Find out more about the economical and easy to use KC7783R PIR motion sensor module
electronics
15:16, 18th Aug 2010

PIR Sensors
Find out how to integrate PIR (passive infra red) sensors into renewable energy applications
electronics
15:16, 18th Aug 2010

LM317 High Current Voltage Regulator
Find out how to build an LM317T based high current voltage regulator
electric circuit
12:29, 17th Aug 2010

LM317 Voltage Calculator
A handy online output voltage calculator for the LM317, LM338, and other linear voltage regulators
electric circuit
12:29, 17th Aug 2010

Optocouplers
Find out more about optocouplers/optoisolators and their uses
electronics
13:33, 14th Aug 2010

Relays and Renewable Energy
Find out more about relays and their uses in renewable energy applications
electric circuit
13:33, 14th Aug 2010



REUK Shop

Popular Items


REUK SUPER TIMER
User programmable 12V powered 10A rated repeating relay timer. 1 second to 99 hours ON and OFF times
£19.99 each.
Complete Circuits



SOLAR PUMP CONTROLLER WITH RELAY
Solar water heating system microprocessor controlled circuit with fitted 10A relay
£25.99 each.
Complete Circuits



12 VOLT 5 WATT SOLAR PANEL
Waterproof 12 Volt 5 Watt Solar Panel with aluminium frame - 290mm x 205mm x 17mm with fitted 5m leads
£33.99 each.
Solar Power



300 WATT POWER INVERTER
Convert 12V DC battery power into 230 AC to power portable televisions, computers, video recorders etc. 300 Watt power rating - peak power 600 Watts
£29.99 each.
Renewable Energy System Parts



CONVERTED PROGRAMMABLE DIGITAL TIMER RELAY
Mains powered programmable timer converted to low voltage with relay board
£21.99 each.
Renewable Energy System Parts



12 VOLT REGULATOR
Supply a fixed 12.0 Volt DC to your devices (up to 1 Amp output)
£4.99 each.
Complete Circuits



MR16 CERAMIC BULB HOLDER
Bulb holder for 12 Volt LED spotlight bulbs
£1.39 each.
Energy Efficient Lighting