I have a Monessen 36" Ventless fireplace. When starting the unit I noticed with the control on "pilot" pressing in and hitting the peizo immediately fires the main burner up. I disconnected the On-Off switch and dont have a thermostat in line. Unit still fires the main burner right up while lighting the pilot. I can short tpth to th and can here a small click but nothing happens. I would like to get the unit functioning on a thermostat but it seems to be all burner all the time. Can someone help? Meter across tpth and th reads 790 or so millivolts. Also the low high knob to control flame height and heat output seems to have no affect when turned at all. Could this all mean the valve feeding the main burner is stuck?