To use legacy heat, we recommend water flow after burner shutdown. This is significant due to the mass
of the heat exchanger plus its internal water volume. Default load settings will run the boiler’s primary
pump for up to 5 minutes (300 seconds) after burner shutdown. Secondary pumps can be set to run up to
15 minutes after burner shutdown (for the last calling load). As shipped, the default settings will run the
Load pump for 5 minutes to place the legacy heat where it is useful. Any secondary pump can be set to
run for 0 – 900 seconds in the heat purge mode. Guard against deadheading pumps when all zone
valves are closed by setting the load Pump Post Purge (sec) to '0'.
The primary pump must be under the control of the boiler to allow pump purge after burner shut-down.
Installers must conform to the piping design configurations provided to simplify the control application,
promote good loads and flow management.
Propylene glycol usage
Warning
Do not use automotive-type ethylene or other types of automotive glycol antifreeze, or
undiluted antifreeze of any kind. This may result in severe boiler damage. Installers must
ensure that glycol solutions are formulated to inhibit corrosion in hydronic heating systems of
mixed materials. Improper mixtures and chemical additives may cause damage to ferrous and
non-ferrous components as well as non-metallic, wetted components, normally found in
hydronic systems. Ethylene glycol is toxic, and may be prohibited for use by codes applicable
to your installation location. For environmental and toxicity reasons, IBC recommends only
using non-toxic propylene glycol.
Propylene glycol solution is commonly used in a closed loop where freeze protection is required. Its
density is lower than that of water, resulting in lower thermal performance at a given flow and pressure.
Generally, a 50%:50% solution of propylene glycol and water requires an increased system circulation
rate (gpm up 10%), and system head (up 20%) to provide performance equivalent to straight water.
These boilers are designed for use within a closed loop, forced circulation, low pressure system. A 50 psi
pressure relief valve (¾" NPT inlet, 1" NPT outlet) is supplied for field installation in the relief valve fitting
on top of the boiler. An optional relief valve, with a rating of up to 150 psi, can be used where required on
closed loop systems. Relief valve discharge piping must terminate between 6" (15 cm) and 12" (30 cm)
above the floor or per local code.
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