Of course geothermal will work for your Dad's home regardless of its condition. Geothermal will be the least expensive way to space-condition. He can continue to use propane for the backup but that may be more expensive than electric heating elements.

I would install a completely variable speed system, compressor & blower, based on the present heating requirements and as the house is made more energy efficient the system can automatically throttle back as the demand decreases, thus saving even more energy.

IMO

SR

Here is a link that might be useful: International Ground Source Heat Pump Association at Oklahoma State University

This post was edited by fsq4cw on Sun, Jul 20, 14 at 20:15

Thesilverback:

Geothermal will likely work however a geothermal system in a poorly insulated home is rare unless money isn't an issue. The installer likely understood that and was trying to save himself some time. Or the installer wasnâÂÂt comfortable designing a system for an old home.

Old homes have very different situations to contend with. Only use a geothermal company (or any HVAC company for that matter) with plenty of experience on old homes. These homes have poor insulation (as you stated) dated windows that leak like a sieve, different building materials and high infiltration rates.

A blower door test as well as the Manual J is critical for such an old home. The tonnage calculations can be way off if the infiltration rate alone is wrong in the Manual J. A poor design on an old home can have devastating results.

Find a geo installer with plenty of experience on old homes first and donâÂÂt compromise. Until you find that experienced installer with old homes, I wouldnâÂÂt recommend geothermal.