Specifications

Logamax plus GB142 applications manual | 01.2012 Technical specifi cations are subject to change without prior notice
GB142 Applications Manual
| 31
3.2 System 2: Single boiler with outdoor reset, multiple heating zones
with zone relays and DHW
Summary:
Single boiler system with a system pump supplying multiple
heating zones with 3rd party thermostats and zone valves.
Use this design for systems with smaller pressure drops, e.g.
baseboard and panel radiators, compared to system 1 which
better handles radiant floors with high pressure drops that
require a separate pump for each zone.
• Outdoor reset for system supply water temperature
• Zone valves are controlled by 3rd party relay panel
• DHW loading with or without priority
• High efficiency outdoor reset controlled system based on
heat loss of the structure
• Automatic warm weather shut down (WWSD)
In detail:
The AM10 outdoor reset controller receives a heat demand
via a closed contact and computes the system supply water
temperature based on information from the outdoor sensor and
the heating curve.
Applications include multiple zones at the same temperature,
or zones at different temperatures if thermostatic or externally
controlled motorized mixing valves are used.
The AM10 provides warm weather shutdown.
The modulating boiler strives to run at low fire for the longest
time possible where efficiency is at its highest.
DHW is heated based on the signal from the DHW tank sensor
FW. DHW is generated in parallel with space heating if both are
calling simultaneously. For faster DHW recovery, install a relay
that disables the zone circulator while the tank loading pump is
activated. Alternatively a zone relay panel with DHW priority can
also be used.
The low loss header decouples the boiler loop from the system
loop.
Required components:
• GB142 boiler
• AM10 controller (incl. with GB142)
• Multi zone valve relay panel with/without DHW priority.
• PH system circulator
• PS DHW tank loading circulator
• ECM pumps (low energy or constant pressure pumps) are
recommended for constant flow rate and additional energy
savings.
• Zone valves
• Room thermostats
Additional instructions:
See manufacturer’s installation and operating instructions for
details on 3rd party components.
The system shown generates DHW with priority over space
heating.
If the DHW sensor in the tank reports a call for DHW, the boiler
will ramp up the supply temperature according to the DHW
setting overriding the outdoor reset heating curve.
The boiler has DHW priority built in. Use the DHW sensor with
the DHW tank and select the DHW temperature using the boiler
dial. During a DHW call the PS tank loading pump will run and
the PK boiler pump will be off. Once DHW is satisfied the boiler
will return to space heating.
If DHW is not installed, set the DHW dial to OFF.