Calculating The Required Groundwater Volume; Permits For A Groundwater/Water Heat Pump System - Viessmann VITOCAL 222-G Technical Manual

Design information
(cont.)
K
approx. 1.3 m
E
-12.0 m
-14.0 m
F
-15.0 m
G
-16.0 m
-20.0 m
-21.0 m
C
A To the heat pump
B Return well
C Delivery well
D Pressure pipe
E Supply pipe
F Non-return valve
G Well pump
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). Delivery 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 flow rate, i.e. the volume of water passing through, depends on
the appliance rating and the rate of cooling.
See "Specification" for the required minimum flow rates.

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].
VITOCAL
N
A
G
M
L
min. 5 m
H
D
K
-11.0 m
D
-14.0 m
-15.0 m
-23.0 m
-24.0 m
B
H Flow direction of the groundwater
K Well shaft
L Primary pump (integrated subject to type)
M Heat exchanger, primary circuit
N Frost stat, primary circuit
O Flow switch, well circuit
■ 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.
Increased flow rates lead to a higher internal pressure drop. Observe
this when designing the pumps.
Permits can be subject to certain stipulations.
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