Calculating The Required Groundwater Volume; Permits For A Groundwater/Water Heat Pump System - Viessmann VITOCAL 300-G Technical Manual

Design information
F
approx. 1.3 m
G
-12.0 m
-14.0 m
-15.0 m
-16.0 m
-20.0 m
-21.0 m
L
3
A Flow limiter, well circuit
B Primary pump (integrated subject to type)
C To the heat pump
D Frost stat, primary circuit
E Heat exchanger, primary circuit
F Well shaft
G Supply pipe
Water/water heat pumps achieve high performance factors. Ground-
water offers an almost constant temperature of 7 to 12 °C all year
round. Therefore the temperature level needs to be raised only a little
higher (compared to other heat sources) in order for it to be able to be
utilised for heating purposes.
Depending on the design, the heat pump cools the groundwater by up
to 5 K, although its consistency remains otherwise unchanged.
■ On account of the costs for pumping systems, for detached houses
and two-family homes, we recommend the pump groundwater from
depths of not more than approx. 15 m (see the above diagram). For
commercial or large scale systems pumping from even greater
depths could still be viable.
■ Maintain a distance of 5 m between the point of extraction (delivery
well) and the point of re-entry (return well). Supply and return wells
must be located in the line of flow of the groundwater to prevent a
"flow short circuit". Construct the return well so that the water exits
below the groundwater level.

Calculating the required groundwater volume

The required ground water flow rate depends on the heat pump output
and the rate of ground water cooling.
For the minimum flow rates, see the heat pump specification (e.g.
minimum flow rate for Vitocal 300-G, type WW 121 = 5.2 m

Permits for a groundwater/water heat pump system

This project requires permission from the "local water authority" [check
local regulations].
Where buildings must be connected to the public water system, the
utilisation of the groundwater as a heat source for heat pumps must
be authorised by your local authority [check local regulations].
VIESMANN
44
(cont.)
B
E
D
A
H
min. 5 m
K
M
D
C
F
-11.0 m
O
-14.0 m
-15.0 m
-23.0 m
-24.0 m
N
H Non-return valve
K Well pump
L Delivery well
M Flow direction of the groundwater
N Return well
O Pressure pipe
■ Due to fluctuating water quality, we generally recommend a system
separation between wells and heat pump.
■ The groundwater flow and return lines to/from the heat pump must
be protected against frost and must slope towards the well.
When sizing the primary pumps observe that higher flow rates result
in increased internal pressure drop.
3 /h).
Permits can be subject to certain stipulations.
VITOCAL 300-G