Lost Electrical Skills. Rough Justice.

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The new building had wall mounted gas heaters with an odd control system, whereby the heater was turned OFF by applying 8 volts, this being obtained from a time switch and a bell transformer. It took a six year old a long time to work out the operating principle.

Was that a short pulse 8 Volts, or did the supply have to be maintained to keep the gas off? Perhaps it latched off after the 8 Volts was supplied?


Z.

No latching, the 8 volt supply had to be on throughout the time that the heaters were not required.

Each gas heater had a continually burning pilot flame, with the main gas supply under thermostatic control. No electricity supply was needed for operation thus. The thermostat controlled the gas supply directly.

For time control a small resistor was fitted to the thermostat, heated by the 8 volt supply and thereby "fooling it" into "thinking" that the room was warm enough and closing the gas valve. 

It was claimed that the very low power of the heating resistance only SLIGHTLY raised the temperature of the thermostat, and that the heater would still operate if the room was very cold, to prevent frost damage.


Even as a young child it worried me that only a single wire was run to each heater with the return via the gas pipe.

Zoomup:

The new building had wall mounted gas heaters with an odd control system, whereby the heater was turned OFF by applying 8 volts, this being obtained from a time switch and a bell transformer. It took a six year old a long time to work out the operating principle.

Was that a short pulse 8 Volts, or did the supply have to be maintained to keep the gas off? Perhaps it latched off after the 8 Volts was supplied?


Z.

No latching, the 8 volt supply had to be on throughout the time that the heaters were not required.

Each gas heater had a continually burning pilot flame, with the main gas supply under thermostatic control. No electricity supply was needed for operation thus. The thermostat controlled the gas supply directly.

For time control a small resistor was fitted to the thermostat, heated by the 8 volt supply and thereby "fooling it" into "thinking" that the room was warm enough and closing the gas valve. 

It was claimed that the very low power of the heating resistance only SLIGHTLY raised the temperature of the thermostat, and that the heater would still operate if the room was very cold, to prevent frost damage.


Even as a young child it worried me that only a single wire was run to each heater with the return via the gas pipe.