Welcome to Eng-Tips! This would be better asked over in forum184 where all the folks who deal with NFPA on a daily basis hang out. If you do decide to post over there, please ask the system administrators to delete this post by clicking the link in the bottom center of your thread that reads "Inappropriate thread? If so Red Flag i!" and letting them know that you've reposted over in the NFPA forum.
Since burner manufacturers have fuel oil burners with turndown ratios of about 10 to 1 as opposed to older designs with turndown ratio of 4 to 1, contact these manufacturers.
