Scott_R
Cursed Dilletente
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Hello all,
I've posted here before, but always with Q's about wells. This is a little different - an HVAC issue. I'm getting ready to replace my 35yo oil furnace before the cold weather arrives - it's inefficient, and oil is killing me. I'm ready to stop enriching Arab Princes (and a few American Oil Princes as well!).
I'm going to go for a Geothermal System (Ground Source Heat Pump) - I've barely got enough well water to serve my domestic water needs, much less "waste" running through a heat pump. So, I'm going to go with a closed loop system - 2000ft of PE buried about 6ft. deep in the yard - this is achieved with 4 500ft. loops, connected back to a breakout manifold, which is in turn connected to a "flow center" (two pumps in series).
The system is sold with a "QT flow center" which has two Grundfros 2699 pumps to circulate the coolant (water + prop. glycol solution) through the loop. My concern is that I live on the side of a "mountain" (really, a ridge) and I have a very steep yard. I'm concerned that these pumps won't be sufficiently strong to circulate the coolant through the loop well (and will burn up pretty quickly). The vendor assures me that based on the loop length, one pump by itself would "almost" be enough. However, I think this is calculated based only on the resistance of pumping through the pipe, and assumes the loop field is level.
So, I have two questions:
1) what is the formula for calculating the friction 'head' of a linear pipe run (this is 3/4" PE pipe)?
2) If the loop is on a hill, regardless of where the inlet/outlet is on the hill, does the energy gained from gravity on the downhill portion of the loop mostly (some loss to friction) cancel out the energy required for the uphill portion?
I assume there is some internal resistance/friction factor for the pipe which is responsible for the 'head' in a horizontal loop, which would cost me some of the downhill energy.
Thanks in advance!
I've posted here before, but always with Q's about wells. This is a little different - an HVAC issue. I'm getting ready to replace my 35yo oil furnace before the cold weather arrives - it's inefficient, and oil is killing me. I'm ready to stop enriching Arab Princes (and a few American Oil Princes as well!).
I'm going to go for a Geothermal System (Ground Source Heat Pump) - I've barely got enough well water to serve my domestic water needs, much less "waste" running through a heat pump. So, I'm going to go with a closed loop system - 2000ft of PE buried about 6ft. deep in the yard - this is achieved with 4 500ft. loops, connected back to a breakout manifold, which is in turn connected to a "flow center" (two pumps in series).
The system is sold with a "QT flow center" which has two Grundfros 2699 pumps to circulate the coolant (water + prop. glycol solution) through the loop. My concern is that I live on the side of a "mountain" (really, a ridge) and I have a very steep yard. I'm concerned that these pumps won't be sufficiently strong to circulate the coolant through the loop well (and will burn up pretty quickly). The vendor assures me that based on the loop length, one pump by itself would "almost" be enough. However, I think this is calculated based only on the resistance of pumping through the pipe, and assumes the loop field is level.
So, I have two questions:
1) what is the formula for calculating the friction 'head' of a linear pipe run (this is 3/4" PE pipe)?
2) If the loop is on a hill, regardless of where the inlet/outlet is on the hill, does the energy gained from gravity on the downhill portion of the loop mostly (some loss to friction) cancel out the energy required for the uphill portion?
I assume there is some internal resistance/friction factor for the pipe which is responsible for the 'head' in a horizontal loop, which would cost me some of the downhill energy.
Thanks in advance!