I haven't dealt with many of these heaters and I've got a small warehouse with 8 of them and everyonce in a while only half the panel will light off. I replaced the flame sensor and for a week it was fine but now maybe 8 out of 10 times it will still only halk light . More then one of the heaters are doing this. I've got the model number if it helps but they're like 2ft squared little heaters. I blew out the panels with some air and was wondering if theyre was some sort of crossover that I'm not aware of? Thanx in advance.