I actually have 4 of them up on my property - only wanted 2, but was sent a double order by the company and figured, what the hey.
I had seen the occasional bat circling the house around dusk, about 20 feet up in the air. Wanting to encourage more bats to come to our property for mosquito control, we ordered the triple-celled houses from batcon.org and posted them about 12 feet up some trees.
I'm not sure, but I don't think they have attracted too many bats in the two years that I've had them up. I still only see the occasional bat on the property. Maybe he's a lost scout or something. There's no guano or other evidence of habitation. Haven't seen anything on the rare occasion that I've shone a flashlight up there in the daytime.
I'm wondering if I should have mounted them on poles - would that have made a difference? I know that poles are safer from predators, but I don't think that we have snakes here, just the occasional raccoon, and a bat at the top of the house is safe from any prying arms/hands. Anyway, I didn't want the hassle of finding/installing the poles. According to
this page it's OK to use trees, but I probably need to move the houses to new spots. Sigh.
Make sure there's an adequate water source nearby. I wonder if the little trickle of a creek on our property is enough.
Anyway, good luck! I'm eager to hear how it goes.
