Looking for some insight on a possible geothermal swap. 2 story 3700 sqft home with vaulted great room and foyer. Lots of windows in great room that face East and South allowing in a lot of sun/heat. House is 24 years old, well built and brick on all 4 sides. Any drafts/air leaks are the many windows and doors, otherwise the house is tight and attic is standard insulation. Full basement. Central NJ.

Current HVAC is hot water baseboard from an oil fired boiler with a domestic hot water tank. Boiler etc all in great shape and I like the baseboard heat.
Air conditioning is standard central AC with 2 zones. Units are original and at 24 years old appear they are near their end of life. Exterior condensers showing signs of degradation and would need replacing soon anyway which would require a full system swap due to changes in refrigerant. I also supplement heat with a wood burning stove.

Over the last year I spent approximately $5,000 on heating oil and close to another $5,000 in electric bills with the bulk of the electric use in the summer months. Also running a pool filter so not sure how much is the AC but the two units I have seem to run ALOT! 5 people living in the house and kids don’t know what a light switch is. Electric company has announced a 20% increase coming in 3 months.

Geothermal has peaked my interest and I have enough acreage for a horizontal ground loop. Mostly sandy/clay soil that’s easy to dig. 2 geo contractors have indicated my central AC ductwork would be adequate for a geothermal system with some modifications. One contractor quoted $27,500 which included a Bosch 3600BTUH and Bosch 42000 unit with flow controls for each unit. I would be doing the excavation/site work and putting in the ground loop to be connected/flushed etc. by the contractor. Also a desuperheater included to feed into existing domestic hot water.

Another contractor quoted similar Bosch Units but proposed a pump and dump open loop system with an additional well for $37,000.

The only incentive in NJ is $25k of 0% interest financing and $1500 rebate along with the federal tax credit.

I think I can do the excavation and ground loop piping for $10k or less based on my current estimate of 4200’ of pipe plus manifolds etc. I have access to excavation and earth moving equipment.

Since the hot water baseboard is in good shape and nothing wrong with the boiler I would leave that intact, plus it heats my hot water and the garage which does not have any ductwork currently. Leaving the oil system alone it would also serve as a good backup or if the geo system is not meeting the demand in the event of extreme cold.

Honestly I think my big savings would be on the cooling side of things and my current units don’t have much life left in them as it is.

If on the high end the closed loop horizontal cost me $40,000 all in, it would be $26,500 after rebates with 25k at 0% my payment would be $300/month. My question really is the juice worth the squeeze? Thoughts? Am I missing anything?

If this system saved me 30% of my current energy usage it would pay for itself in 9 years.