Ground Source Heat Pump Replacement

Design Heat Loss: 19.6 kw (67,100 BTU/hr)
Heat Pump Capacity: 13.7 kw (46,900 BTU/hr)
Geothermal System Type: Closed Loop Lake Coils
Location: Puntzi Lake, BC (Central BC / West of Williams Lake, BC)

New Geothermal Heat Pumps typically have higher efficiencies than older geothermal heat pumps.  The increased efficiency is usually achieved by increasing the size and/or flow rate through the heat exchanger coupled to the ground exchanger.  Therefore, replacing a ground source heat pump requires careful attention to the required flow rate and pressure drop through the geothermal heat pump to ensure the existing centrifugal pumps are capable of meeting the geothermal heating and cooling system demands of the home.

Earth Fire Energy received a project to replace an existing Nordic Geothermal Heat Pump.  We compared the capacity, efficiency, pressure drop, and required flow rate of the existing ground source heat pump to the replacement geothermal heat pump.  The new geothermal heat pump had higher capacity and better efficiency, but had a higher pressure drop and required a 50% increase to the flow rate.  Therefore, we performed a pump calculation to determine the pressure drop through the geothermal system at the higher flow rate.

The existing centrifugal pumps were significantly undersized to provide the required flow rate for the replacement geothermal heat pump, so there were a couple of options to choose from:

1.       Add a third pump in series with the existing two pumps, which required some piping modifications.

2.       Replace both existing pumps with larger capacity pumps.

3.       Replace one of the pumps with a larger capacity pump.

The client had specified they were on a limited budget, so we chose Option Three because it resulted in the lowest capital cost by limiting the equipment purchase to one pump and it enabled us to reuse a majority of the existing piping for the geothermal system.

Below are some photos of the new Nordic Geothermal Heat Pump installed.