I need some advice on sizing a pump and loop system. I have three 1.5 ton heat pumps that need 6 gpm. My plan is to install one in the basement and one in the upstairs. I have a one acre pond 200 feet from the house with a rise of 18 feet. Any advice? Thanks AJ

To select a pump for a pipe system, you first need to know the pipe characteristics (i.e., pipe diameter, length and friction coefficient) and the required design flow rate so you can work out what the pipe hydraulic friction head will be. Then you select a pump that has a performance curve that places this flow rate and head in the center of its performance curve. You can use software like this:

Borst Pipe/Pump Design Software (Hazen-Williams)

Borst Pipe/Pump Design Software (Darcy-Weisbach)

Please be sure to read the associated software instructions and you would either be doing 2 (open pipe/pump design) or 3 (closed pipe/pump design). Hazen-Williams is limited to water at 60F pumped at turbulent flow rates, which is typical of most water work projects. Darcy-Weisbach doesn’t have this restriction, but requires entering additional fluid parameters (i.e., fluid density and dynamic viscosity).

There are likely also ground source heat pump issues that need to be considered and addressed that hopefully someone more knowledgeable in this subject than me can help you sort out.

So you need 13.5 gpm for the 3 heat pumps.

(6) loops in the pond, 400ft each 3/4" pipe,

2" header pipe, 200ft each way to the pond, (could be 1.25" too for a bit more pumping power). (1) small variable speed pump would work. 8.7 ft/hd pressure drop in the loop field incl. header pipe.

Open loop from a pond is not a good idea (algae, fish eggs, other stuff),

So you need 13.5 gpm for the 3 heat pumps.

(6) loops in the pond, 400ft each 3/4" pipe,

2" header pipe, 200ft each way to the pond, (could be 1.25" too for a bit more pumping power). (1) small variable speed pump would work. 8.7 ft/hd pressure drop in the loop field incl. header pipe.

Open loop from a pond is not a good idea (algae, fish eggs, other stuff),