Laars NEOTHERM NTH Series, Инструкция по установке и эксплуатации

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Page 48
LAARS Heating Systems
(For a complete explanation of the Lead Lag system, see
Section 8.14.)
When using the Lead Lag boiler system to provide indirect
domestic hot water heating, the DHW demand should be
supplied to the Master boiler through the existing DHW
terminals. The Lead Lag system will change the operating
mode of just the Master boiler to supply water at the DHW
setpoint. The remaining boilers on the system will continue
to supply hydronic heating.
When the system is supplying both hydronic heat and
domestic hot water at the same time, both the System
pump and DHW pump contacts are closed, so special
attention must be paid to allow for proper operation. In
applications serving both hydronic and domestic heating,
during a DHW call the Boiler pump on the Master boiler
may need to be turned off. The DHW pump will provide
flow through the boiler and indirect tank when there is a
DHW call. (This means the DHW pump must be sized
properly.) To turn off the boiler pump in this application,
the “boiler pump interrupt” jumper must be installed. The
terminal block location is terminal block 5 (TB5) at the
contacts labeled “boiler pump interrupt” in the control
panel.
Sensor Connection for Domestic Hot Water -
Connect the DHW sensor or aquastat.
If your system has just one boiler –
Connect the sensor across terminals 5 and 6 on TB6.
See Figure 30 on page 45.
If your system has more than one boiler, and is
controlled using the Lead/ Lag function –
On the unit used as the Lead/ Lag Master only, connect
the sensor across terminals 5 and 6 on TB6.
Domestic Hot Water Heating
Using External Modulation Control -
When the Unit is used for DHW heating with external
modulation control, a call for heat must be supplied to the
“T-T or Interlock” terminal. By supplying a call to the “T-T
or interlock” terminal, the operating temperature setpoint
defaults to the hydronic heating setpoint, so all of the
temperature adjustments must be made to the hydronic
setpoint. When the unit receives the call, the control starts
the Boiler and System pumps and begins the ignition
process. Once in Run, the Unit monitors the flame signal,
call for heat, safeties, and water temperatures. The heater
setpoint is used to limit the maximum water temperature
leaving the boiler only. The modulation rate is controlled by
a 4-20mA signal supplied by an external control. (This can
also be 0-10Vdc using a converter.) When setting up a sys-
tem using an external control, take care to set Anti-Short
Cycle feature to prevent “hunting “ and possible premature
component failure.
Boiler Pump Interrupt Function -
The boiler pump interrupt feature is used in some
applications when the boiler is being used for both hydronic
and domestic hot water heating. The interrupt jumper is
used to turn off the boiler pump during a domestic hot
water demand. For this to work properly the system must
be plumbed and pumped to allow the DHW pump to supply
the flow and head requirements for both the boiler and
indirect water heater. It is not necessary to use the interrupt
jumper in all applications.
To turn off the Boiler pump in this situation, the “boiler
pump interrupt” jumper should be installed between R1 and
R2 on TB5.
If your system includes several boilers, is controlled using
the Lead Lag system, and the indirect DHW tank is con-
nected to the boiler acting as the Lead Lag master, install
the boiler interrupt jumper on the Lead Lag master only.
WARNING
Failure to plumb, pump and install the unit correctly
when using this feature may lead to reduced or no
water flow through the heat exchanger, causing pre
-
mature failure of the heat exchanger, personal injury
or death. Please consult the factory with any questions
regarding the use of this feature.
Setup for DHW Control Functions -
1. Set up the correct priority for the DHW function in
relation to Central Heat or Lead/ Lag demands. If a call
for heat and a DHW demand arrive at the same time,
which will have the higher priority?
If your system has just one boiler –
How to get there: From the “Home” screen, press “I” to
go to “Info/ Install.” Choose “Advanced Setup,” then go
to “DHW Configuration.” Select “DHW Priority vs Central
Heat.”
If your system has more than one boiler, and is
controlled using the Lead/ Lag function –
How to get there: On the unit used as the Lead Lag
Master, from the “Home” screen, press “I” to go to “Info/
Install.” Choose “Advanced Setup,” then go to “DHW
Configuration.” Select DHW Priority vs Lead Lag.”
2. Set the setpoint for the DHW function.
If your system has just one boiler –
How to get there: From the “Home” screen, press “I” to
go to “Info/ Install.” Choose “Advanced Setup,” then go
to “DHW Configuration.” Select “DHW Setpoint.”
If your system has more than one boiler, and is
controlled using the Lead/ Lag function –
How to get there: On the unit used as the Lead Lag
Master, from the “Home” screen, press “I” to go to “Info/
Install.” Choose “Advanced Setup,” then go to “DHW
Configuration.” Select “DHW Setpoint.”