LAARS NeoTherm NTV1000 - Install and Operating Manual - Manual (Page 85)

NeoTherm Boilers and Water Heaters Page 81
9.5 Setup for Domestic Hot Water on
a lead/lag System
There are three ways that a NeoTherm 1000 system
can be set up to provide domestic hot water. Two
of them involve the use of an indirect water heater.
In a system including an indirect water heater, hot
water is circulated through a piping loop which runs
through an insulated water tank. Heat from the water
in the loop is transferred to the water in the tank, and
the heated water in the tank is used as domestic hot
water.
Setup type 1 –
All of the boilers in the system can be set up to react
together if there is a call for domestic hot water. This
arrangement can be used for NTH or NTV units.
When NTH units are used in this kind of setup, the
demand for domestic hot water (DHW) is given
priority over the demand for central heat (CH). If
the system is producing heat for a CH demand, and
a call for DHW arrives, all of the boilers will stop
producing heat for CH, and the whole system will
respond to the DHW demand. The DHW pump will
start circulating water through the loop in the indirect
water heater. The System sensor is used to control
modulation in this configuration, so sensor placement
is critical.
This arrangement can be cumbersome if the demand
for domestic hot water is a lot less than the demand
for central heating. This can result in multiple boilers
“idling” as they wait for the DHW demand to be
satisfied.
Caution
For NTH units - This arrangement can only be
used in applications where all of the components
in the system are rated for both the maximum
hydronic temperature and the maximum DHW outlet
temperature.
The setup for this is all done from within the Lead/
Lag system. You will need to set up an LL CH
setpoint and a separate LL DHW setpoint, and assign
the priority to the DHW demand.
The input from the aquastat is brought to terminals
5 and 6 on TB6 on the controller which is acting as
the Lead/Lag Master. (Usually, this is the Primary
controller on Boiler 1.)
1. From the Home screen (Fig. 111), press the
View Lead Lag button.
fig. 111 – Home Screen
2. If the system was running, the following screen
would normally show the current activity of
each unit in the multiple boiler arrangement.
See Fig. 112.
fig. 112 – lead/lag Screen
3. Press the button for Lead Lag Master. Fig. 113
shows the screen that follows.