Geo Thermal Heating & Cooling

[Grub]

Anybody here have a geothermal heating and cooling system? We are in the process of getting together information for a major remodel of our home and geothermal is one of the upgrades we are looking at. I have some pricing, but I wonder if it's really worth the extra expense. Look forward to some feedback.

[KY Blue in Carolina]

Grub wrote: Anybody here have a geothermal heating and cooling system? We are in the process of getting together information for a major remodel of our home and geothermal is one of the upgrades we are looking at. I have some pricing, but I wonder if it's really worth the extra expense. Look forward to some feedback.

There are several ways to apply geothermal technology, but I assume you're looking at using a ground coupled water source heat pump loop. In your area, it would definitely save some.... whether or not it would pay back in a reasonable time - I have my doubts. What's the price differential? I'd also recommend you consider service and maintenance costs (you'd have both). Most residential heating and cooling service providers will not have people used to working on water source heat pumps - you could end up paying commerical service rates, which run about double.

There are some manufacturers with duel fuel units that I would consider highly.... heat and cool with a heat pump (air coupled) as long as ambient air temperature is above 35 degrees.... operate with a gas furnace (natural or propane) below 35 degrees. I'd have to do some research on the average seasonal temperatures in your area to fully assess. With relatively cheap electricity and mild winters here in the Carolinas it looks quite advantageous here. Will investigate when I need to replace a unit (not soon I hope).

[Grub]

I've been quoted a ground coupled Waterfurnace Envision unit. Budgetary quotation is between 13-15K. Thats figuring $3,500 for the loop system, $2,500 for the newductwork and around $8,000 for the unit - all installed. We currently have an electric heat pump (circa 1964). Where we're located, LP gas is the only other option we might have.The existing structure has acrawlspace foundation, but the new addition will have a basement area where all mechanical will be located.

I was told I could figure $4,500 to $5,000 less for a new electric heat pump unit.

Link: http://www.waterfurnace.com/envision/index.aspx

[UedK]

Most geo installers have the capability to provide a life cycle cost (payback) analysis for the system you are considering. If you supply them with your past one or two years utility bills they should be able to give you a very close payback analysis. As per KBNC's advise, the life cycle cost analysis should include annual maintenance costs.

I have been involved in a few institutional building conversions to geothermal and we usually look for a three to five year payback. In the several larger projects I have been involved in the payback goals have been met. These have been buildings with a full time maintenance staff that learns the system and keeps up the maintenance. With a water circulation system you will find yourself learning about circulation pumps that run 24/7.

The projects I have been involved in have been water source heat pump closed loop systems with deep drilled wells in which the closed water pipe system is run to achieve the geothermal effect. This is a relatively maintenance free system in that the water (or water substitute) is very controlled and stable. If you are considering a system that uses direct ground water for the geo effect it can become very maintenance heavy. I know of two facilities in Louisville that abandoned geo systems that applied direct ground water from the aquifer because of upkeep and maintenance. Untreated water can be very damaging to the internal components of circulation pumps and heat pumps or what ever heat transfer systems may be employed.

We have priced geothermal systems on new construction and have never been able to afford one when priced against conventional HVAC systems. The new comparative cost is usually double when dealing with, say a 20,000 square foot commercial building with gas fired heating/electric condensing unit cooling with a ducted supply and return conditioned air system.

[Chaz]

Grub, I have Geo in my house and it was a conversion from a heat pump system. My system was installed 14-15 years ago. I have a 2 story house and had 2 separate systems installed in order to regulate the temps both up and down. I have a closed loop antifreeze filled in ground system. The first year the energy costs savings were minimal because the heat transfer was not optimum at that time. It take a year or so for the dirt to settle around and "pack" around the inground pipes, thus affecting the heat transfer. The ground temp for your area should be similar to mine and it is around 55 degs year round. After the second year my heating costs were about half of what I spent on the heat pump. Heat pumps are only efficent down to 40 degrees. After that, aux electric coils kick in and the cost goes up.

If you go with Geo, make sure that you get a corresponding hot water heater. In the summer, when you are cooling your house, you will basically get "free" hot water as the heat being drawn from your house is used to heat your hot water. Geo is much more eficent in summer than a reg A/C as it is using 55 degree water instead of ambient 85-95 deg out side air.

Maintenance is not bad. In 15 years, I've replace one reversing switch, and one other electrical module. The circulating pumps were replace with in the past year anter 14-15 years of use. These pumps run only in the same manner as the circulating fan to move the heated air through the duct work. As with any heating system, regular air filter change outs will affect performance.