Description of the device
Servimat M/L — 28.01.2021
English
—
5
4.3.1
Type code
No.
Type code (example)
1
Device name
2
"VG" primary tank
Servimat M
VG 500 VF 500
3
Nominal volume
1
2 3 4 5
4
Secondary tank
5
Nominal volume
4.4
Function
1
Secondary tank (optional)
2
Primary tank
3
Vacuum spray pipe
WC
Make-up pipe
DC
Degassing line
•
Gas-rich water from the system
•
Degassed water to the system
EC
Expansion pipe
•
Pipe to the expansion vessel
•
Pipe from the expansion vessel
The device is a pressure maintaining station for heating and cooling water
systems. It is used for maintaining pressure, making-up and degassing the water
in heating and cooling systems. The device comprises a control unit consisting of
a controller with hydraulic system, vacuum spray pipe and at least one expansion
vessel.
Expansion vessel:
One primary tank and multiple optional secondary tanks may be connected. A
membrane separates the tanks into an air and a water space, preventing the
penetration of atmospheric oxygen into the expansion water. The "VE" pressure
compensation elbow connects the air space with the atmosphere. The primary
tank is hydraulically flexibly connected to the control unit. The function of the
"LIS" level measuring using a pressure pick-up is thus ensured.
Control unit:
The control unit comprises a control module and a hydraulic module.
•
Control module
Comprising the Control Touch controller and the power connection unit.
All pressure maintenance, degassing and make-up processes within the
hydraulic module are monitored and controlled by the Control Touch
controller.
•
Hydraulic module
The
hydraulic module comprises the pump “PU”, the overflow valve
“PV/RKH1” and the make
-
up valve “WV/MKH1”.
The "PIS" pressure sensor records the pressure and the "LIS" pressure pick-up
registers the level; both values are indicated in the Control Touch display.
Interfaces enable the use of additional Control Touch functions see chapter 6.4.3
"RS-485 interface" on page 13 .
The device fulfils three functions:
Maintain pressure:
•
The pressure in the facility system rises when the water is heated. When
the pressure set at the controller is exceeded, the "PV/RKH1" pressure relief
valve opens and drains water from the system into the primary tank, using
the "EC" expansion pipe. The pressure within the system drops. The
pressure in the facility system drops when the water cools. When the
pressure drops below the set value, the "PU" pump is activated and uses
the "EC" expansion pipe to transport water from the primary tank back into
the system. The pressure in the facility system rises. The controller ensures
that the pressure is maintained, further supported by the stabilisation
provided by the "MAG" pressure expansion vessel.
Degassing:
Two "EC" expansion pipes are required to degas the system water. One pipe is
intended for gas-rich water from the system, while one return pipe returns
the degassed water to the system. During the degassing action, the "PU"
pump and the "PV/RKH1" pressure relief valve are in operation. The pump
creates a vacuum in the spray pipe
. •
Gas-rich water is conveyed via
the degassing line connection from the facility system to the vacuum spray
pipe and degassed. Details see chapter "Sequence of a degassing cycle in
the vacuum spray pipe" on page 5 . This process can be applied in two
different variants (continuous and interval degassing).
Make-up with water for the facility system.
•
When the water level in the primary tank falls below the minimum, the
"WV/MKH1" make-up valve opens and make-up into the tank continues
until the set level is again reached. During the make-up process, the
number of requests, the time and the make-up time within a cycle are
monitored. Using a FQIRA+ contact water meter, the system monitors each
individual make-up quantity and the overall make-up quantity.
The Servimat provides the following safety features:
•
Optimisation of all pressure maintenance, degassing and make-up
sequences.
•
No direct intake of air thanks to a regulation of the pressure
maintenance with automatic make-up.
•
No circulation issues caused by free bubbles in the circuit water.
•
Reduced corrosion damage due to oxygen removal from fill and
make-up water.
Sequence of a degassing cycle in the vacuum spray pipe
1
Create vacuum in the spray pipe
3
Discharge
2
Injection
4
Idling time
The degassing operation uses timer-controlled cycles. A cycle comprises the
following phases:
1.
Create vacuum in the spray pipe.
The pump starts and conveys water from the vacuum spray pipe. The
pump transports more water from the spray pipe than can be transported
via the connection lines of the water make-up. A vacuum is created.
2.
Injection
Opening of the “PV” overflow valves in the “DC” degassing line routes gas
-
rich water into the spray pipe. It is atomised by nozzles in the spray pipe.
The atomised water is degassed in the vacuum of the vacuum spray pipe
because of the large surface area resulting from the atomisation. The
degassed water is returned to the facility system via the vacuum pump.
The pressure relief valve means that the pump is set to a constant working
pressure. The working pressure depends on the respective facility system.
