Solar Bread Box Batch Heater
Solar Bread Box Batch Heater
Find out how to put together the simplest kind of solar water pre-heatersolar | water | heating
There are many different types of solar water heater
ranging from simple solar camping showers
to whole house evacuated tube solar heating
systems. Each type of system has its benefits and disadvantages and of course the variation in price
can be extreme.
In this article we will look at solar Bread Box
) heaters. These are very cheap
to put together, very reliable, require no pump
or electricity, and can be put together with simple easy to source components.
Solar Bread Box Heater
A solar bread box heater
can be used where mains water is available, and it pre-heats water before it reaches the boiler
. (Note that this may not
work with some combi boilers
if their internal electronics often cannot deal with water over 30 degrees Celcius entering the boiler where it expects cold
water to come in.)
Pictured above is a schematic of a bread box
based solar water heating system
. Mains water enters the solar heater at the bottom where it sits and gets heated up by the sun. When someone turns on the hot tap (drawing water from the boiler), the water warmed in the bread box
is pushed (by mains water pressure) into the bottom of the boiler. Here it is heated further (if necessary) by the boiler until the water reaches the temperature set on the thermostat
A standard electric water heating tank makes a perfect batch heater
when it is painted black
. This tank just needs to be fitted into a well insulated wooden box (or old fridge or freezer) with a glass
window on one side through which the sun can shine. In the northern hemisphere the heater should be fitted facing southwards to maximise the solar radiation
absorbed by the water in the tank.
Every degree you pre-heat water
using such a bread box
heater, is one degree you do not need to heat it with your boiler - therefore even the most basic system will save money
and reduce your energy costs.
If you have a greenhouse
then if the tank can be fitted high up near the apex of the roof, it is possible to get vast amounts of hot water
for 9 months of the year at the same time as preventing the greenhouse from getting too hot.
In locations where frost
is likely in the winter, ideally the batch heater (and pipework) should be fully drained
so that no pipes burst. Mains water typically arrives at homes (in the UK) at around 5-7 degrees Celcius. Therefore, if it is cooler than that (and not sunny) outside, this heater
would actually cool the water before it gets to the boiler. Since this is hardly ideal, a valve
should be fitted so that you can manually configure the system to bypass
the heater at these times.
For a basic guide to soldering copper pipe
, click here.
Article Last Modified: 11:52, 16th Sep 2008
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