Hi, last June my boiler cracked, I decided to go with a geothermal system instead of replacing my oil system. My house, located in norther NJ, is a 2 story side hall colonial approximately 1400 sq/ft built in 1992 it's fairly well insulated but I wouldn't consider it to be a tight house by today's standards. The contractor I chose added ductwork, and installed a vertical closed loop system with a 450' well, a 2 ton split system for my upstairs, and a 2 ton package system for my downstairs (geocomfort 2 stage). He was very professional as were his subs, electric, well driller, plumber and HVAC installer and his references checked out well. The system was turned on in late October. Initially it heated well, as the weather cooled we began developing issues, the downstairs couldn't keep up and cooled to 64º a couple of nights. He came out, closed a basement return closed the supply but later opened the supply only, I also realized the old oil flue was not sealed. WIth those items changed the system began working much better. This past December was cold for NJ, it's now Jan. The last couple of days I woke up to 65º downstairs. My supply air is barley 80º this seems cool to me. We've never seen it higher than upper 80's. My fear is that my well, drilled mostly through granite and very little water, is not sufficient for the load. I'd appreciate any thoughts you may have. Thanks

Try energy efficient insulation.

I don't know what you consider cold, but geo systems in colder climates usually have a backup heat portion for helping the system in the extremes. This could be an electric coil, a water coil heated from say an on-demand water heater, or in rare cases a backup small boiler such as a Munchkin modulating unit.

It sounds like your system is working well, except for the extremes. It is possible the contractor slightly undersized your needs, the desired constant temp, so the 450' well only provides a comfort level down to a specific outdoor temp.

Discuss adding a backup heat source for the times when the system just cannot handle the load!

Before spending any money on auxilliary heat, do a more serious energy audit. (Sort of what hunter12 said.)

If it's staying above 60F indoors at peak loads you're close enough that even modest improvements in air-sealing plus some spot insulation could turn the corner, which would likely be less money up front than a backup system, and would provide a net savings on energy use as opposed to an increase to provide the same or better comfort level.

If this is a typical 1990s house with low density R38 fiberglass batting in the attic, note that when it's in low single-digits outside it's performance will be more like R30 (or less) due to convection loops through the insulation layer. An overblow of 3-4" of cellulose would be a cheap fix, sufficiently blocking those convection loops to restore it's cold-weather performance, and adds ~R12 to the stackup making it more like a true R50 at 0F outdoor temps. In combination with a round of air-sealing the system would likely keep up, with margin to spare. (It's probably even subsidized by the state in NJ.)

Geo-air is always on the cool side, which is why duct registers are better placed where they minimize the wind-chill to human skin. Air temps of 80f can be sufficient to heat the place, but feels pretty cool to skin, especially in an air-leaky house where the relative humidity drops below 30% when it's cold out. Air sealing would raise the average indoor humidity too, making it more comfortable even in the air-stream.

Buy some cheap humidity monitors- if it stays above 35% RH at 68F or higher indoor temps when it's been below 20F outdoors for days you may want to consider active ventilation to purge moisture, but it sounds like getting it that tight could take quite an effort. You're probably below 20% RH @ 68F indoors when it's below 20F outside.

Also, if this is a full basement with uninsulated walls & slab, the basement walls could easily be 15-25% of your whole house heat load (sometimes more.) It's a chunk of change, but insulating basement walls. and foam-sealing/insulating the foundation sill & band joist can be huge from both a comfort and heating-capacity point of view. See: http://www.buildingscience.com/documents/reports/rr-1003-building-america-high-r-foundations-case-study-analysis

If you go the basement insulation route, make sure you keep the perm rating of the foundation foam 1-perm or above unless you're positive that there are capillary breaks under the foundation wall and at the slab edge, as well as at the foundation sill.

A serious round of basement insulation could cost you as much as a gas-fired boiler backup system, but it would be more comfortable year-round, and your annual energy use would go down, not up. In NJ 1" of XPS against the foundation wall, band joist & foundation sill (foam sealed at the edges) + unfaced R13 batts in a studwall would deliver the drying capacity needed to protect the foundation sill, with low enough winter condensation risk that you wouldn't end up with mold. See case 4 in that .pdf document, and note that your climate is significantly warmer than Minneapolis (the climate where the hygro-thermic simulations were for), which means your condensation risks are even lower, and no interior vapor retarder like kraft facers or retardent paints would be called for (and might even increase the risk.)

Be sure to use something like sheet-poly or sill gasket under the bottom plate of any interior studwall. It may be worth stopping the foam 6-8" from the slab too, to let the bottom of the foundation dry toward the interior, especially if there isn't a capillary break such as a foam sill-gasket under the foundation sill at the top of the concrete.

Post this question to the geotherm forum. There is some real knowledgeable installer over there that might give you a simple answer.

I strongly agree with FBBP. In fact, The state Board of Public Utilities says 160 New Jersey homeowners have converted to geothermal since 2007 and that the interest, while small, is growing. So I guess, it's time that you go geothermal, too.

Try to check this http://www.posharp.com/geothermal-energy-companies-in-new-jersey_renewable.aspx?ptype=geothermal>ype=us_NJ