No, the overheat stat blows open circuit in-line with the thermocouple to prevent the pilot light from being re-ignighted. There is no reset option, it must be replaced.
Short term - and very temporary for obvious safety reasons - you can get the boiler running again if you bypass the overheat stat by shorting accross the contacts (look for two black wires with spade connections) that are presented on the thermocouple entry point to the gas valve.
WARNING: Your overheat stat blew for a reason! FIX IT!
If it blew due to running the system while empty and forgetting to turn the boiler thermostat down to its OFF position - i've done that accidentally - then you should be ok to run it with the above bypass in place.
NO NOT LEAVE THE BOILER UNATTENDED WHILE USING THE ABOVE BYPASS! - EVER!
Source your replacement overheat stat ASAP and fit it as a matter if urgency for your safety and your neighbours.
You wouldn't like to be responsible for blowing up half the street now would you, should something go terribly wrong! :-)
Dave (not qualified, but more than competant) ;-), November 2009
