fitzyfitta
09-06-2012, 06:48 PM
Customer has a 2 stage heat/cool rtu that feeds a 4 zone mastertrol system. Dampers are powered open/power close. I found a mab II-3 panel and a model maz-7 panel. None of the low voltage is labled and i have yet to trace it out to figure which zone each t-stst and damper is wired to. Last winter customer replaced old mercury stats with with new white rogers non programable 2 stage stats. The problem is whenever any 1 of the t-stats is calling for 2nd stage cooling the rtu will run and the other offices will also cool down below setpoimt on their t-stat due to the fact the dampers are not completely closed off. I did this with evey stat and noticed the led for damper open was always red (closed) on every zone. I have never came across this mastertrol zoning system but was told by maintance giuy that rtu should only run when any 2 of the stats are calling. I did find and read the wiring diagram for the 2 stage heating and cooling system. It states i must use a Mastertrol changover 2 stage tstat (model mcts) for zone 1 which is a 8 wire stat. My question is can i use the current w/r stats that have 8 terminals y1,y2,w1,w2,r,g,o,b. Also does anyone have any literature for this zone control other than the panel wiring diagram i have. TIA Fitz....