While installing gas meters today , I noticed that one of our many new home builders had installed a couple of the Heatilator ND3630I Direct Vent Fireplaces in two of their new homes. These particular units had the Intellifire ignition system which utilizes a 3 volt control box and spark ignition for the pilot along with a variable Dexen control valve. This unit is new to me and I was just curious as to how reliable this ignition system is? Are these a new system or have they been around awhile? I did notice in the owner's manual that the back-up battery pack and the 3volt transformer cannot be used at the same time, either one or the other ,and if using the transformer the batteries cannot be installed in the battery pack! I also noticed that the wall mounted wall switch for the fan must be wired with a 14-3 wire from the switch to the junction box, a little bit different from what I'm used to seeing. Anything in particular one should be aware of when trouble-shooting this system?