I'm in the midst of my second ICF build.  The first was in the upper midwest, this is in the south.  2600sqft, full ICF (foxblocks), full basement.  I can't decide if the upcharge for GEO is worth the payback even with the 30% uncle sam giveback.  Looking at costs, I hae been quoted $39K for GEO (3 ton waterfurnace) 25K for conventional.  Systems include trane electronic air cleaners, renewaire air to air exchange, renewaire ultra quiet bathroom fans.

Does anyone think these prices are out of line?  Please express your opinions on the subject as I am closing in on teh first pour and need to get the penetrations sleeved before proceeding.

$39K - 30% ($11.7K) = $27.3K
Out of pocket up charge for Geo = $2.7K
Likely energy saving for geo = $300/ton/year= $900 annually
Payback time= 3 years= annual return on investment 33.3% = no brainer

Tough to judge if price is reasonable, don't know what is part of your system. Given that a conventional system is kind of high, too, makes me believe that you have a lot of options in there. $14K upcharge for geo as a 3 ton system sounds reasonable.