I recently replaced my old mercury tilt thermostat with a programmable (5/2) Honeywell RTH230B digital unit. I didn't have too much problem with the install - to a 2 wire forced air oil furnace - however I find the furnace cycling through start and stop much more than usual,to the point to distraction, up to 4 or 5 times in a 10 minute period sometime only starting for 10sec or so just to maintain a 70F temperature. I can only imagine this will get worse as the cold months (I live in Atlantic Canada) arrive. Is this normal or is there a setting or installation problem I may have missed?

Take a look at the instruction manual, page 3 Configuration Menu, where it mentions how to program the heating cycles per hour. This should help.

Ok... I wasn't entirely sure that's what the 'cycles' pertained to, thank you for the post. I'm still a little curious though - when the unit cycles on it will heat for a few moments, stop for ~2 minutes. Then cycle on again for 15sec. I can only assume this counts as two cycles. As the unit is defaulted to 4 cycles should I set it to higher to ensure it stays warm when the weather gets colder? I see in the manual it recommends 3 cycles/hr for high efficiency furnaces (which mine is) but I can't imagine that would be enough the way it is operating now. Am I mistaken?