Ground Source Heat Pump Questions

[blimkie.k]

I am researching ground source heat pumps, however I do not completely understand how they work.

I understand that a pump uses a small amount of electricity to pump heated ground water or an antifreeze solution through the a system of piping in the ground to transfer heat from the ground to a home. What I don't understand how this actually heats the house to a comfortable temperature in some areas.

On this site, http://www.davocal.ie/Assets/services/eco_friendly/eco_friendly.php

it says in this country (not sure where) the ground temperature several metres down varies from 10 - 13 degrees.

This document, http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/rp/rp33/rp33.pdf

on page 7, shows a chart that shows a chart of ground temperatures for Ottawa, Canada (which is near where i live) in clay. At 15 feet below the surface the temperature varied from 45-50 F over the year in 1954-1955.

So say the ground is around 50 F and you have your piping with antifreeze running through there, how is that going to work on its own to heat a home. Is there a way that the system can obtain a higher temperature via friction or running through the pump or would the ground heated solution need to be pumped through another heating unit above ground to give it another 15-20 degrees of heat to allow it to heat a home to a comfortable temperature.

Also I know that Environment Canada takes readings of the ground temperatures twice daily at 60,000 locations across Canada. I have been looking for there publications or reports but can't find any. Does anyone know where to find these?

 

[russ_watters]

The ground loop is just where the heat pump gets or dissipates its heat. It isn't what a "heat pump" is.

A heat pump is a device that uses a refrigerant to create a temperature difference which causes heat to move in the opposite direction you would normally expect it to move. For example, an air conditioner moves heat from inside your house to outside your house despite the fact that the air outside is warmer than inside (making the heat want to go from out to in).

A "heat pump" is just an air conditioner working in reverse. On a cold day, heat wants to go from inside to outside, but the air conditioner makes it go from outside to inside.

The way this is done is by utilizing the thermodynamic properties of the refrigerant to generate different temperatures. Inside your house, the pressure is raised, which heats the refrigerant. This heat is then extracted to heat your house, cooling the refrigerant back down somewhat. Then the pressure is relieved, which makes it cool even further, below the temperature of the source/sink (outside air or in your case, a water source). Then heat is put back into it from this heat source. Repeat!

http://en.wikipedia.org/wiki/Heat_pump