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How to Build a Hothouse

How to Build a Small Hothouse - The Heating System

Heating of small greenhouses may be done by means of oil - burning stoves, electrically heated "strips" placed at intervals around the house, or by hot water pipes heated by electric heating units. The hot water is most satisfactory because it distributes the heat evenly around the walls and needs little attention. The lay-out of the electrically operated hot water system is shown above, where a cistern holding about four gallons of water has a two kilo-watt immersion heater controlled by a thermostat which cuts off the current when temperature rises above requirements and switches on again when temperature falls. Cast iron pipes, 2in. diameter, and rising about 1/4in. per foot run take the hot water to the opposite end of the house and piping with equivalent "fall" brings the water back to the cistern for re-heating.

At "A" is a funnel into which water is poured to replace the small evaporation and at the end of the other pair of pipes is a safety valve made from about a foot of half inch pipe fixed vertically.

Clips from the bench bearers will support the piping and most of the work is within the scope of all amateur who can buy his pipes cut to length and screwed for the necessary bends and unions. This system takes advantage of the off peak night loading rate allowed by the Electricity Commission.

A coke fed system will need a small cast iron boiler properly set up on a brick base and complete with flue and insulation. Allow also for 70ft. of 2in. pipe, a small expansion tank and the necessary boiler connections. also a thermometer.

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How to Build a Hothouse