GSHP: Ground Source Heat Pump - Design
Indirect Pond Loop
The slide show above seques through the conversion of the pond to the thermal sink for an indirect pond loop GSHP.
This a tiny pond by all the rules of thumb.
-- There is a large water flow from 2 springs
-- It ices over only when temps drop into the teens and quickly re-melts.
Using spring water directly with a heat exchanger creates a maintainence task, and a limited life for the heat exchanger as it reacts to oxygen, minerals and chemicals in spring water - and the solutions needed to keep it "clean".
Using the pond and indirect loop as a huge heat exchanger is:
-- Maintainence free
-- Chemical free
-- Uses fewer resources - as it won't need replacement
-- Would be applicable to use in true "dirty" water environments
Though too small for stratification I've seen evidence it does at times.
Why does this matter?
Efficent GSHP tubing / coil placement.
We all know hot water rises, but, cold water rises too, surprise! From about 40 to freezing cold water rises.
Backup Plan: The indirect gshp loop in the pond will tranfer the greatest part of the BTU load, but, there is potential in the grounds to "finish it off". If the pond and spring flow does not work, I can easily drop a double run of 1 1/2 inch tube at the bottom of a 6 foot deep trench, and get over 600 feet of tubing, enough for 1/5 the load plus, which can also be thought of as 1/5 of the typical 10 degree delta T on the ground loop, or, 2 degrees. GSHP Site Work - Practice and Theory
Energy Savings and Carbon Reduction
YES
Ground source heat pumps do:
-- save energy - SOURCE energy!
-- reduce carbon use!
-- use renewable energy - geothermal energy and solar energy!
Consider the entire Life Cycle Analysis, as LEED v4 is moving to embrace.
