I went to help my colleague to wire thermostat for rediate heater. my colleague is going to use one thermostat control three radiat heaters. he is going to use two transformer(40va, 120v/24v) parallel instead one 75va transformer. but I notice the longest heater is 120' away from the thermostat. and he is using the 16awg cable. I suggested him to use a larger gauge cable, but he said the old one work fine use this cable. I check the menu, they suggested 30'for 16awg. does anybody know how much voltage drop is ok for the gas valve and ignition module. does the cable length will affect the heater operation?