We looked at them a year or so ago, and one thing that stopped us getting one is that the ones we checked needed to be placed some distance, maybe fifteen feet, from any open flame re: heater etc. Well in our place the coincidence between reccommended locations and being that far from either the stove or the furnace just didn't work out.
We didn't want the stupid things doing false positives when we turned on the stove. i also believe I remember some time limits like you mentioned. tom Fowle
