Geothermal Heating

I've started doing some research on geothermal heating systems.  This is something that I'd really like to install in my house because of the superior efficiencies that you can get with this system and the fact that you aren't generating any greenhouse gases--at least at your house.  Unfortunately, Nova Scotia Power still generates the majority of it's electricity using fossil fuels.  (Reference: wikipedia,  NS Power)

With a geothermal system and a water source heat pump you can get COPs (coefficient of performance) of around 3.5 to 4.5 depending on the unit you are using. The coefficient of performance is the ratio of energy output to energy input.  So the higher the COP rating on your heat pump, the better it's performance.

I found some great information on how geothermal heating systems work in residential applications at Maritime Geothermal Inc who manufacture geothermal heating units out of Petitcodiac, New Brunswick.

Image from: Nordic Geothermal Inc

I quickly realized that a geothermal system in my location (the city) would mean that I'd need to go vertical with a geothermal well, since there just wasn't the room in my backyard for a horizontal ground loop (or two).  I found some great information on geothermal wells from Brewster Well Drilling.  I phoned them and an extremely helpful guy Philippe Gingras met me at my place and we talked about how the systems are installed and the costs.

Here is some of the information I found out:

• Rule of thumb for geothermal well installs is 150 feet of well depth for every 1 Ton of heating load from the heat pump.  So a 4 Ton system would need a 600 foot deep geothermal well.
• 600 feet is their drilling depth, so if you needed more than a 4 Ton system you'd need another well.
• They like to locate the wells as close to the mechanical room (where your heat pump will be) as possible.
• The top of the well is around 5-6 feet from the surface of the ground and you can pave over it with a driveway or put grass over it.
• The supply and return lines from the well are run in a trench to the side of your foundation where they core drill a hole through the foundation wall, into your basement where the lines run to your heat pump.
• It costs about $21 per foot to drill a geothermal well.  So a 600 foot deep geothermal well will cost you roughly $12,600.  This would be the installed price including drilling the well, installing supply/return lines, filling the well with grout, trenching from the well to the side of your house, and bringing the supply/return lines into your house.  This would be a budget price and assumes that digging in your yard doesn't require breaking bedrock to get the 5-6' depth above the well, repairing your driveway, etc.
• Geothermal systems are best suited for new home installs.  This is because they work best when they are used as heat sources for in-floor radiant heating systems or via hot air forced through ventilation duct work in your house.  You can also use it in a combination of the two, so that you can reverse the heat pump in the summer and air condition your house using the duct work.
• Geothermal systems can be used in renovations, but they are most economical when you already have ventilation ducts installed throughout your house and your present heat source is either close to needing to be replaced, or leased so you can cancel the lease and have the old equipment removed.
• A drilled geothermal well would work great at my property and they would install it in the driveway, which is right next to the house.  This, I thought, would be great since I am thinking of putting my new mechanical room at the back corner of my house, next to the driveway.  Also, the driveway needs to be replaced soon, so if they had to rip part of it up to drill the well, it wouldn't matter much.
• The budget price to install ventilation duct work in my house would be in the $5-6000 range but I got some names of a couple of mechanical contractors they work with to narrow that cost down.  I'm thinking that I can cut this cost down if I were to install the duct work myself, but I'd still need to know how to do it properly.
• The budget price to install the heat pump and associated equipment that would extract heat from the geothermal well would be in the $4-5000 range.
• All told I'd be looking at a budget price of $25-30,000 to install a geothermal system.  Whoa!
• The federal government used to offer a $4,500 rebate for geothermal installations, but they canceled the program last year. Thanks Steven Harper!

Have geothermal questions? Contact Philippe Gingras at Brewster Well Drilling: 902-456-0517 (cell) and 902-832-4758 (fax).