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01-22-12, 05:48 PM   #4 (permalink)  
IF you have a milivolt system then you can not do that! When Rh and W are shorted that connects the milivoltage produced by the thermopile is transferred from the Rh wire to the W wire which connects to the gas valve completing the circuit. If you were to interject 24VAC on the Rh terminal you could ruin the gas valve. A milivolt system is a DC system which uses less that 1VDC. Are you sure you have a Milivolt system? It very well could be that you have a 24V heating only 2 wire system which is not a milivolt system.