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Depending on the heat transporting medium you can use systems with brine or with
refrigerant.
Ground heat collectors will be used if there is enough flat space (garden surface).
This system needs the lowest investment costs. You will need an area of 1 to 1.5
times the area inside the house to be heated.
Borehole heat exchanger are the solution where you have practically no space
available. They are drilled about 65-100m deep and use a good portion of geothermal
energy.
For some heat sources you will need an authorization.
Heat capacity of ground collector
Heat capacity of borehole heat exchanger
Ground type
Heating hours per year for heat pump
for 1,800h
for 2,400h
Dry, non-cohesive ground (sand)
approx. 10W/m2
approx. 8W/m2
Cohesive ground, damp
approx. 25W/m2
approx. 20W/m2
Saturated ground (sand, gravel)
approx. 40W/m2
approx. 32W/m2
Specific abstraction capacity
Remark:
Specific abstraction capacities according to VDI4640, with an installation
clearance of 0.8m.
Fou nda tio ns
Hea tin g ho urs p er y ea r for he at pu m p
fo r 1 ,800 h
fo r 2 ,4 00 h
Stand ard va lu es :
Po or s ub so il (dry se dim e nt) (<1.5W /(m *K ))
25 W /m
20 W /m
Norm a l b ed ro ck a nd sa tu ra ted
Se dim en t (+1.5 -3 .0 W /(m *K))
60 W /m
50 W /m
Be droc k with a high th erm a l co nd uc tiv ity(>3.0 W /m *K)
84 W /m
70 W /m
Type s of stone :
G rave l, sa nd , d ry
<2 5W /m
<2 0W /m
G rave l, sa nd , a qu ife ro us
65 -8 0W /m
55 -6 5W /m
G rave l a nd s an d with stron g grou nd wa ter c urre nt, for
sing le sys tem s
80 -1 00 W /m
80 -1 00 W /m
Clay, loa m , d am p
35 -5 0W /m
30 -4 0W /m
Lim e ston e(so lid )
55 -7 0W /m
45 -6 0W /m
Sa nd ston e
65 -8 0W /m
55 -6 5W /m
Ac id ic ig ne ou s ro ck (e .g . g ra nite)
65 -8 5W /m
55 -7 0W /m
Alka lin e igne ou s roc k (e .g. b as alt)
40 -6 5W /m
35 -5 5W /m
G ne iss
70 -8 5W /m
60 -7 0W /m
Spe cific abo stra ction c apa city
Remark: Typical specific abstraction capacities for borehole heat exchangers (double
U pipes) according to VDI 4640 Part 2.
INSTALLATION & INSTRUCTION
MANUAL