13 boiler pump interrupt – LAARS NeoTherm NTV600 - Install and Operating Manual User Manual

Page 41

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NeoTherm Boilers and Water Heaters

Page 39

NAME

FUNCTION

VALUE

CH on

Burner demand begins when the

5°F

differential

outlet water temperature reaches
"Outlet water temperature setpoint"
minus "CH on differential"

CH off

Burner demand ends when the

5°F

differential

outlet water temperature reaches
"Outlet water temperature setpoint"
plus "CH off differential"

DHW on

Burner demand begins when the

2°F

differential

outlet water temperature reaches

(80-285)

"Outlet water temperature setpoint"

5°F

minus "DHW on differential"

(399-850)

DHW off

Burner demand ends when the

10°F

differential

outlet water temperature reaches

(80-285)

"Outlet water temperature setpoint"

5°F

plus "DHW off differential"

(399-850)

Pump

Operates the pump for the overrun

1 or 5

overrun

time after the burner demand

minutes

has ended

High

Locks the boiler out when the high

200°F

limit

limit temperature is reached
(requires manual reset)

Flame

Flame signals lower than the flame

0.8Vdc

threshold

threshold interrupt burner operation

DHW

Time for domestic hot water priority

60 min.

priority time

Table 15. Default Control Settings.

DANGER

• Water temperature over 125°F (52°C) can cause

severe burns instantly or death from scalds.

• Children, disabled and elderly are at hightest risk of

being scalded.

• See instruction manual before

setting temperature at
heating appliance.

• Feel water before

bathing or showering.

• If this appliance is used to

produce water that could
scald if too hot, such
as domestic hot water
use, adjust the outlet
control (limit) or use temperature limiting valves to
obtain a maximum water temperature of 125°F (52°C).

operation there are several settings in the "setup" menu
structure that must be adjusted for the specific
installation, each is covered in the following sections.

8.12.1 Lead Lag Setpoint
The lead lag setpoint is set from the "user" menu

using the "LL" variable. This is the temperature the
boiler is attempting to maintain at the system sensor.
This setting doesn't control the boiler outlet
temperature, so the water temperature at the boiler outlet
may be much hotter than the system temperature
setpoint. Adjust the LL setpoint to the desired operating
temperature of the system.

8.12.2 Lead Lag Master/Slave Selection
In the SETUP menu structure, the "LL" menu

allows the lead lag system to be turned on and the boiler
to be configured as a master or slave control. In each
lead lag system there can only be one master control, so
proper selection is important to avoid operating issues.
To set the boiler to lead lag "master" operation the LL
menu should be set to "LDR". To set the boiler to slave,
"SLA" should be selected.

8.12.3 Lead Lag Address
The Lead Lag address must be set for each boiler

connected to the lead lag system. Each boiler must have
a unique address selected for the system to work
properly. Typically, the lead or master boiler should be
set to address one and the remaining boilers should be
set to values 2–8 depending upon how many boilers are
installed in the system.

8.12.4 Lead Lag Hysteresis
The lead lag system uses a hysteresis value set in

the setup menu, called, "HS". The hysteresis and
setpoint values control the on and off points of the
boiler. If the lead lag setpoint is adjusted to 120°F with
a hysteresis value of 5°F the boiler will turn off when
the water temperature reaches 125°F and will turn back
on when the water temperature reaches 115°F. Set the
hysteresis values to match the boiler to the system
operating characteristics. Setting this value correctly

will help reduce the chance of short cycling.

8.12.5 Lead Lag Base Load Setting
The lead lag system uses a base load setting that is

set through the "setup" menu called "bL". The base load
setting identifies the firing rate that the operating boiler
must achieve before the next boiler in the system is
allowed to operate. The default setting is 50% to avoid
short cycling and operating the boilers at higher, less
efficient, firing rates.

8.13 Boiler Pump Interrupt

WARNING

Failure to plumb, pump and install the appliance
correctly when using this feature may lead to reduced
or no water flow through the heat exchanger, causing
premature failure of the heat exchanger, personal
injury or death. Please consult the factory with any
questions regarding the use of this feature.

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
domestic hot water pump to supply the flow and head
requirements for the boiler and indirect water heater
together. It is not necessary to use the interrupt jumper
in all applications. Specific modes of operation that may
require the use of this feature are shown in

Section 6

.

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