Thermostat calls for heat and the exhaust blower turns on, but that's it. Gas does not ignite, it just sits there with the blower running.
could be you pilot light is out. could be you have a spark egnitor instead. May have gone bad. Call a pro to check it out. Gas is nothing to mess with. Could take down you house.
Take the cover off the boiler and look for the controller (it will have all the wires running into it). There may be some indicator lights on it that can tell you what is wrong. All boilers go through a series of safety checks before firing. Yours is probably failing one of these checks.
