Veissmann Viola Bifferal oil burning residential heating boiler not firing properly. Runs blower for 5 seconds, fires for 1 second, runs for 5, fires for 1, cycle continues 5 or 6 times, then may run properly or may just quit. Replaced flame sensor and does not make a difference. Any suggestions?

Yes contact a qualified ON SITE service person. That boiler is not something to play with unless you have been to there school and know what you are doing. There have been problems with the ignition and related parts my reliable sources tell me.

Veissmann Viola Bifferal

http://www.viessmann-us.com/en/produ...la_200_TDM.pdf