7
Pump mounting flange dimensions:
4.1 Suction conditions
The bottom of the pump strainer must be at least
25 mm above the bottom of the tank, see fig. 2 or 3.
MTH pumps must be installed vertically and the drain
hole in the motor stool must have access to the tank.
The pumps are designed to provide full performance
down to a level of A mm above the bottom of the
strainer.
At a liquid level between A and B mm above the
bottom of the strainer, the built-in priming screw will
protect the pump against dry running.
Fig. 2
MTH 2 and 4
Fig. 3
MTH 8, 12 and 16
5. Electrical connection
The electrical connection should be carried out in
accordance with local regulations.
The operating voltage and frequency are marked on
the pump nameplate. Please make sure that the
motor is suitable for the electricity supply on which
it will be used.
Single-phase Grundfos motors incorporate a thermal
overload switch and require no additional motor pro-
tection.
Three-phase motors must be connected to a motor
starter.
The terminal box can be turned to three positions,
in 90° steps, see fig. 4.
Proceed as follows:
1. Remove the four bolts securing the motor to the
motor stool.
2. Turn the motor to the required position.
3. Replace and tighten the four bolts.
4. Replace the coupling guards.
The electric motor should be connected to the supply
as shown in the diagram inside the terminal box
cover.
Fig. 4
Terminal box positions
6. Start-up
Before starting the pump, make sure:
• that all pipe connections are tight.
• that the pump body is partly filled with liquid
(partly submerged).
• that the strainer is not blocked by impurities.
Start the pump as follows:
1. Close the isolating valve on the discharge side of
the pump.
2. If the pump is fitted with a vent valve, this valve
must be opened, see fig. 5.
Pump type
D1
D2
D3
L
C
X
MTH 2 and 4
140 160 180 121
Rp ¾
ø7
MTH 8, 12
and 16
180
210
200
100
Rp 1¼
ø9
Pump type
A [mm]
B [mm]
MTH 2 and 4
37
25
MTH 8, 12 and 16
40
25
TM
00
48
41
38
97
TM0
1
432
6
5
2
9
8
Never make any connections in the pump
terminal box unless the electricity supply
has been switched off.
If the pump is not connected to an electric
installation, it must be connected to an
external mains switch.
B
A
25 mm
25 mm
B A
TM
03
53
56
34
06
Pay attention to the direction of the vent
hole and take care to ensure that the
escaping water does not cause injury to
persons or damage to the motor or other
components.
