Lennox signature 2 stage furnace, 9 years old. Had a new tstat installed last season and tech had to modify the wiring. IIRC he tested operation of both low and high (second) stage heating. Got my tune up for this season and tech said there was no wiring for the second stage. He added a jumper and told me that the furnace is more efficient running in second stage. So now it starts in first stage and very quickly (a few seconds) goes to second stage. Assured me that Lennox heat exchangers, in general, do not crack and my delta T was well within spec at second stage. And that a single stage furnace normally runs at the higher gas pressure (3.5) anyway. I really don't see how it is more efficient. Yes, set temp is achieved quicker and the blower runs for a shorter period of time, but higher speed. I have actually heard that you want a system to run almost constantly (or is that a/c?). With a 2 story house it seems like running the blower as much as possible would help equalize the temp. I know people have their own ways of doing things and opinions on what is best, this just seems odd to me and after running it one way for 9 years now I've got a big change. Previously I was under the impression that it would only go to second stage as needed, and that would be rare. What is the point my having a 2 stage furnace if it runs nearly all the time at 2nd stage? Is running it this way indeed better? As a comfort issue, I find it annoying that I hear more airflow at the vent (noise). Because heat rises and this is a 2 story house we did close down the second story vents, I wonder if adjusting the dampers a bit would help?

Long story short, I've been producing my own biodiesel and running it exclusively in my AFG furnace for about 12 years, full B100 home produced, roughly 350 gallons a year. I've done much of the maintenance myself, and some items I had found a local tech that would handle. Most did not want to touch my system because of the biodiesel. The tech has now retired, and I've been unable to find anyone that will touch the system while fueled by biodiesel. About a year ago, the pump was replaced by the tech. First time in 12 years. The original pump was a webster m34dj-3. Who knows how old it was. Longer than I'd lived here. It was replaced with a A2VA7116. It's now about a year later, and while it's still working fine the pump has gotten very loud and I can't help but feel the biodiesel may have degraded the internal rubber parts of the pump. I've found that the webster m34dm-3 is actually rated for full bio, but I've ran into a confusing problem. From what I understand, the m34dj-3 is a clockwise pump, from the "D" in the model designation. The pump on the system now has an arrow on it showing counter clockwise rotation. How the heck can this be? I'm certain of the original pump, as I have photos I took, and I can clearly see the direction printed on the currently installed pump. I'd like to use the m34dm-3, but it is a clockwise pump. I can't find a counterclockwise bio pump. So will either direction pump work and it's just a matter of routing the lines to the right spots, or do these things only turn the specified direction? How the heck could I have had 2 pumps working in different directions? It's not like anything on the burner has been replaced that would have changed the direction of the pump required?