The heat pump was ~Cdn$18,000 installed, and that included the thermostat and all the duct changes. The fan on a GHP (ours is a Water Furnace E060) is way more powerful than a typical oil or gas furnace, and small ducts will result in more wind noise than many would want. Luckily, our house had a huge old oil furnace and large ducts already installed. The ducts nearest the intake and outlet have dense sound insulating material which helps a lot. Our unit is set horizontally because of a low ceiling; vertical models with the same performance are less expensive and easier to install.
The heat exchanger is two 4x8' stainless steel panels connected by a manifold to allow the antifreeze solution in the closed loop to dump or pick up heat from the pond. It is possible to have a 6F difference in temperature between in and out, so the pond needs to have enough volume or flow to handle it without freezing or overheating. (Read about the Geo Lake Plate at
www.awebgeo.com) The 2 x 200' of tubing to the pond, the heat exchanger and all labor and taxes brought the total cost up to ~$25,000.
This may seem like a lot for a heating system but we had to replace an old oil furnace, an oil hot water heater and an indoor oil tank. Their replacement costs would have been around $11,000 for an efficient oil system (gas is not an option where we live)--and if we wanted even just basic air conditioning in a couple of rooms, we'd need to add another $1,000 or so. So, the GHP option really costs "only" ~$13,000 more than oil. For that, we end up with more space in the basement, no oil tank, no devices using fire to heat--and can feel good about reducing our carbon footprint!
Even better, the payback will be faster than we'd expected: our first year's energy cost was $1,700 less than the year before. The GHP provides most of our hot water during winter and summer, and we get full-house air conditioning. As well, the cost typically adds the full amount to the resale value of a home and are several programs provide rebates (up to $7500 in many parts of Canada).
Since a GHP heats by circulating warm air instead of adding hot air in bursts, the heat (and A/C) is much more consistent throughout the house, and heat from any rooms with solar gain or a wood stove gets moved around to reduce the need for heat even further.
We're upgrading many of our windows and insulation in a renovation this summer, so we could probably have managed with a smaller unit.
If you are making a pond, I'd highly recommend considering how you could use it for a GHP.
Eric
