Anyone ever rebuild a midco direct fired burner? I have always dealt with Maxon and feel the midco is a (POS). Not to mention their tech support. I came across a MUA unit direct fired that was producing alot of raw gas. After much observation the following was noted. Burner neg. static is -1.2" with the valve de-energised and fan on. Low fire modulation (MR Valve aprox 5-11 vdc) the burner manifold is operating at -.01 to -.2 Above 11 vdc the manifold moves into a positive, and a strong raw gas smell will be present from grills. Someone rebuilt the burner a few years ago and used pipe dope on the flanges where the burner sections bolt together. Midco states they must be sealed with furnace cement (which seems crappy)or the section joints will leak. Supply to regulator is 7"
Regulator is a maxitrol RV61 which mods on flow. The burner is an older model MA 500 The burner is a 750,000 BTU ( 3 6" sections) I noticed the burner is "BLACK" or no flame at the section joints at higher firing rates. Any thoughts?