Example -ground Example

For exemplification, we will use again a heat pump installation with thermal power of 10 KW, and a 8.0 KW collection power.

The volumetric flow rate is of 2353 L/h at a temperature difference of 3,4 K.
 2353 L/h : 4 probes = 588 L/h/probe.

Practical example

The probe farthest from the distributor is probe –D–.

Computation of the connection pipe length (4)

 Section D – C 5.00 m Section C – A 5.00 m Section = A – distributor Ca.12,00 m Simple pipe = 22.00 m Double pipe(return circuit) 2x 22.00 m = 44.00 m

Explanations on the sections

relating (1): pressure loss per probe = 300 mbar at 588 L/h

relating (2): pressure loss per meter of pipe length 25 x 2.0 mm la 588 L/h = 1.88 mbar /m
On the entire pipe length = 44.0m x 1.88 mbar/m ≈ 83 mbar

relating (3): pressure loss per distributor = 40 mbar
intermediate result:  300 mbar + 83 mbar + 40 mbar = 423 mbar
423 mbar = 42300 Pa = 4.23 m transport height water-ground pump

relating (4):
on the connection pipe between the distributor and the heat pump:

 Available pressure of the water/ground pipe = 550 mbar (see technical specifications of the heat pump producer) lost pressure 1 - 3 ./. 423 mbar Constant pressure = 127 mbar Required volumetric flow rate = 2353 L/h

On 1.0 m of pipe with interior diameter of 20 mm, at a volumetric flow rate of 2352 L/h a pressure loss of approx. 5.7 mbar/m is produced. In case of a constant pressure of 127 mbar, the computation is as follows: 127 mbar:5.7 mbar/m = 22.10 m max. pipe length

On 1,0 m of pipe with interior diameter of 32 mm, at a volumetric flow rate of 2352 L/h a pressure loss of approx. 2.1 mbar/m is produced. In case of a constant pressure of 127 mbar, the computation is as follows: 127 mbar: 2.1 mbar/m = 60.50 m max. pipe length

In case of a total pipe length of the connection pipe ranging from 0.0 to 22.0 m, the diameter nominal DN 25 is sufficient. If you exceed this length, then the appropriate higher diameter must be selected.

If the pipe between the distributor and the heat pump does not have to be configured by you, but by the manufacturer of the thermal installation, then simply notify him about the pressure loss up to the distributor, inclusively.

Relating (5): The technical data of the heat pump manufacturer include in this section the "available pressure".
or "free pressure" or "residual circulation height".
This value already contains all incidental pressure losses of the heat pump.
In our example we have considered an initial available pressure of 550 mbar.
If these values are not mentioned, ask the heat pump manufacturer.

Centralization:

1. Measurement of the volumetric flow rate: 8000W : 3.4 K = 2352 L/h
2. Minimum number of probes:
2350 L/h :
600 L = 3.92 = 4 probes
3. Computation of the pressure loss per sections / probe distributor (1-3) and distributor - heat pump (4)