Anyway, would you please tell me what to do with a fireplace. It will go into the gable end (simple one story ranch), new construction, 400 sqft room which is open to another "great" room (the current LR/kitchen). We have a great mason, and prices here are reasonable.

I'm concerned that a new design high eff unit might be too hot - as the fireplace will be used for looks and ambiance most of the time (we do get ice storms, are rural and can loose power, but after one year or so, we will have a whole house backup genset).

1) Is a prefab unit (quality) going to last 25 years
2) Is a prefab hi eff unit going to be too warm
3) Would the cost diff btw a "real" fireplace vs. a prefab (with masonry chimney, hearth and all) be worth it.
4) Would a pre fab unit provide greater energy savings during the time it is not being used (draft protection summer and non fire winter).
5) Any suggestions for units would be wonderful (i.e. tell me what to buy)

Thanks in advance for doing my work for me.

Kai

Then a prefab will do the trick quite nicely. And why not have a gas log set too? That way it won't get 'too hot' and you'll have the looks of a real fireplace without the cost and hassle of a masonry unit.

A real fireplace is actually a heat loser. More household heat will go up the chimney in a fireplace than a stove. So having a gas unit with doors on it should suit you just fine.