Laars NeoTherm NTH Installation and operation instructions manual - page 24
LAARS Heating Systems
Page 24
to install an anti-scald device may lead to property
damage, personal injury or death.
5.3 Pump Connections
The boiler pump is wired at the factory (pump
mounted models only). The NeoTherm Control
energizes the pump upon a call for heat. Once the call
for heat is satisfied the pump will remain on for the
defined pump overrun time.
NOTE: System and DHW contacts are dry contacts.
The appropriate voltage must be supplied to the
contacts for proper operation.
The system pump connections are located on
Terminal Block 5 in the control panel (
see Figure 18
).
The system pump contacts are rated for 120Vac, 7.4
amps. To use the contacts power must be supplied on
one terminal. The other terminal wired to the pump or a
contact controlling the pump.
The DHW pump connections are located on
Terminal Block 5 in the control panel. The DHW pump
contacts are rated for 120Vac, 7.4 amps. To use the
contacts power must be supplied on one terminal. The
other terminal wired to the pump or a contact
controlling the pump.
5.4 Temperature Control
The NeoTherm temperature control measures the
temperature on the outlet sensor, measuring the supply
water temperature. Set the control setpoint for the
desired supply temperature.
5.5 Temperature Control - Indirect Tank
For indirect domestic hot water applications a
DHW sensor or mechanical aquastat may be used to
determine the domestic load call. The sensor or aquastat
should be connected to Terminal block 6 connections
labeled "DHW temp sensor". The sensor is a dual
element sensor. The Laars sensor is the only sensor that
can be used with this controller. To connect an aquastat
use the middle and far right terminals on TB6, labeled
"DHW temp sensor". Once a sensor or switch is
installed, the call should be "Autodetected" by the
control (
see wiring diagrams, page 26
).
When the DHW sensor is used the boiler modulates
off of the DHW sensor using the DHW setpoint. The boiler
loop temperature is allowed to operate to the limit setting.
To assure correct operation, proper temperature settings
and system plumbing is required to eliminate short-cycling
and nuisance lockouts.
When an aquastat is used for the DHW demand,
the boiler modulates off of the outlet water temperature,
using the DHW setpoint as the target temperature.
5.6 Outdoor Reset Operation
Outdoor reset varies the control point setpoint
based on the outdoor temperature. The reset function
works as shown in
Figure 19
. When the Outdoor air
temperature reaches the High Outdoor temperature
setpoint (HOD), the control point is adjusted to the Low
Boiler temperature setpoint (LBT). When the outdoor
air temperature reaches the Low Outdoor temperature
(LOD) setpoint, the control setpoint is adjusted to the
CH setpoint temperature. To access the LOD, HOD and
LBT variables, refer to
Sections 5.2.2.3
through
5.2.2.5
.
To access CH setpoint, refer to
Section 5.2.1.1
.
An outdoor air temperature sensor must be
connected to TB7 in the control panel. The connection
Figure 18. Control Panel Layout.