Rather than answering which combustion analyzer should I buy or which is the best I want to start a thread to address the real question.
The answer is, "If you don't have one you shouldn't be in any house or building that has any fuel burning appliances"!!! We have all the tools and training for air conditioning and yet I rarely see where anyone was poisoned or killed by an air conditioning system. I cannot believe we jeopardized the safety of the public daily because we don't think we need an analyzer, we can't afford one and we certainly don't need to learn how to use it!!!
It is so much easier to say if we don't test then it is not our fault if someone is injured, but that is a crock!! If this was still the 19th century I would understand. We all can afford computors, cells phone, ipods, plasma TV's etc., but we can't afford the tools to do our jobs nor are we interested in attaining the skills to learn how to use them. It is not the analyzer that makes the difference, it is the person using it. If the equipment is failing odds are it is the user fault. I throw, bounce, kick, freeze, overheat just about every make analyzer on the market and they still work fine.(not that I recommend doing those things). It is my way of letting people which units hold up the best in the field. To date, Bacharach, Testo, TSI and even UEI have survived. On the other hand, moisture will kill all of them and if proper removal of water is not adhered to they all fail prematurely.
Water heaters and then unvented gas ovens lead the list of appliances that cause the most poisoning and deaths. So unless you are in a state that don't bathe or bake then maybe you don't need one..
Every fall the media advertises on make sure your furnace is safe for the winter and call a qualified contractor. Unfortunately less than 10% are qualified to do a thorough equipment safety check or whole house safety check.
We had a conference in a hotel in S.C. in February. The water heaters for the hotel were installed improperly, not venting properly and slowing poisoning guests in certain rooms. When I notified the hotel engineers he got mad at me and chewed me out. Guess I will wait for the lawsuit. Just checked a furnace that poisoned a lady in May and found it to be producing over 5110ppm of CO. Would have gone higher but didn't want to injure anyone. Because this was with a lawyer the amount of measureable CO was critical. This was in the furnace not the room. The room was monitored the whole time.
I really don't care what analyzer anyones buys, don't have a problem with who is making a deal, we all have our preferences, but please buy one NOW! and learn how to use it before more people die.