Thank you for your input. It would be used in very limited circumstances, and only when someone was in the house. There seems to be a question, however, as to whether the milivolt output of the thermocouple would be sufficient to complete the circuit. The gas valve is a Honeywell VS8421 and a response from a tech there said I would probably have to have a previoulsy unused thermostat since the normal make-break of the contacts in it causes some arcing (which I presume creates resistance in the circuit).