If the Backup heat is so ineffcient, what would the negative effects if I disabled it. I assume it will take longer for the house to heat up, and in the case of an older air to air heat pump would not be able to heat the house once the outside temperature falls below a certain temperatures. For Water to Air geothermal, are there any negative problems if i disable it?  Anyone know exactly when the backup heat kicks in for air to air heat pumbs and when its completely on backup heat?

I have a geothermal water to air heat pump. I have disabled the back up heat. You can do this by unhooking the "w" wire on the thermostat. Can't help up with the air source heat pump.

I expect the "when" varies system to system.

I have a dx system and I disabled resistance heating years ago.

Perhaps you shoudl call the installer or system source to find out how to best do it.

It depends if your area is a heating or cooling dominant area. If heating, then every heat pump needs backup heat. The problems that can arise are that you can rob the ground of heat too much. Every geothermal heat pump needs time for the ground to recover. If not enough time is given, you're headed for problems. Each manufacturer is different on the design as to how much duty cycle the heat pump should have.

What you need to know is the balance point temperature. If the outdoor temp. drops below balance point, the backup heat really should come on. To find balance point, you need the accurate load calculation of your home and the capacity of your heat pump at design temperature and no load conditions.

The point is, if your heat pump has been properly sized and designed, the amount of time that your backup heat will run will be very minimal. It will hardly affect the cost of heating. But, for the few times that the temperature does get colder than usual, your backup heat needs to be hooked up to assist the heat pump.

Hope this helps.

Can an extra well be added in lieu of backup heat for geothermal HVAC?

In some situations, hypothetically yes.

The problem that can arise is too much oversizing. Oversizing results in less comfort and higher bills. Also, it's not like it only costs $300 to just have another ton of capacity added to the system.

The situation does happen where you can't help but oversize. My brother is buying a townhome that's under construction. He is a driller for my sonic rig. Because he can do the drilling himself, and my dad and I are the sales reps, he can get the geothermal at a decent price. But, the smallest EarthLinked geothermal we have available is a 2 ton. It only needs a 1 ton. With that being the case, the balance point will be -67 deg. F. We've had a cold winter, and have reached -40 in the past, but I doubt he'll ever need backup heat.

However, backup heat is still a good idea. We'll definitely include it on his system. Let's say it's Christmas eve, and a component of your geothermal heat pump goes out. How nice would it be to have the backup heat ready and able to keep your house from freezing until you can get it serviced? With the right controls, the backup heat won't be allowed to turn on until balance point, or emergency.

I would never install a geothermal without backup heat.

So it's possible my geothermal system doesn't have backup heat? I just assumed it was a standard part of the system. Looking at the system, or opening up the unit, how can I verifiy this?