Term
Thermo Electric Valves
KEYWORDS |
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Definition
Electrically operated valve.
coil creates magnetic field that holds gas valve in open position
No electrical supply will cause a spring to close the valve |
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Term
Thermo Electric Valves
Where Found ? |
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Definition
C/H Boilers ,W.A.U as part of composite valve
Water Heaters, fires and cookers |
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Term
Thermo Electric Valves
TESTS |
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Definition
| Should fail safe within 60sec (audible click) |
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Term
Thermoelectric Valves
FAULTS |
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Definition
Fails to shut off within time period.
Fails to hold open (also Thermocouple could be at fault) |
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Term
Thermoelectric Valves
WITH INTERRUPTER |
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Definition
Thermocouple to the valve will be interrupted by a safety device such as TTB or overheat
This breaks the voltage circuit to the valve from thermocouple when a fault occurs
Shuting the appliance down. |
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Term
Thermoelectric valve
F.S.D
Alternative names: thermocouple |
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Definition
T
he thermocouple tip, when heated by a flame, creates a small electric current which flows al
the wire to an electromagnetic coil inside the valve. The coil generates a magnetic field which
hold open the gas valve.
If the flame is extinguished the thermocouple tip cools, the current and magnetic field disappear
the valve springs shut, stopping gas flow. |
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Term
| Testing a Thermoelectric valve |
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Definition
Run the appliance until it reaches normal operating temperature. Achieve flame failure by turning
off the gas supply at a suitable upstream isolation valve. Ensure the valve clicks out within the
acceptable time limit. Ensure gas flow has been stopped (e.g. with a manometer downstream of the
thermoelectric valve).
For many appliances the maximum cut out time specified by British Standards is 60 seconds, but the
appliance manufacturer may specify a different time. If click-out takes longer, or if gas continues to
flow afterwards, the valve is faulty.
If a valve takes less than ten seconds to click out then the thermocouple may be close to failure.
Inspect the tip, wire and connections carefully for signs of burn-out, corrosion or damage. |
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Term
Interrupted thermoelectric valve
Flame supervision device with secondary shut off
Alternative name: interrupter (spelt “interruptor” by some suppliers) |
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Definition
This device works in the same way as a thermoelectric valve with the addition of an electrical
connection in series to an overheat thermostat or other safety device. If the safety device activates
it opens the circuit, stopping current to the thermoelectric valve and shutting down the appliance.
Test: as for thermoelectric valve. There is no means of simulating overheat conditions outside a
specialist testing facility. |
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