IBC Sl Series Installation & Operating Manual page 52

Section: Installation
3.11.2.1 Primary-Secondary piping
For optimal performance, place pumps on the supply side of secondary loops to facilitate air
evacuation. Use pumps with internal check valves to avoid ghost flows and thermal
siphoning. Primary/Secondary piping ensures adequate flow and de-couples Δ°T issues
(boiler vs. distribution). It also adds to the system's thermal buffering, to assist in handling
small loads and temperature transition. Aim for a 20 °F to 30 °F Δ°T across the heat
exchanger at high fire (there is a boiler protection throttle fence limiting the Δ °T to 40 °F).
A primary-secondary piping configuration requires an extra pump, independent from any
secondary load pumps. The controller hosts wiring terminals and integral relays to simplify
installation and operation of this preferred layout, offsetting such costs.
For best results regarding the SL 14-115 G3, use a Primary/Secondary piping system with a
pumped boiler loop (using 1" piping). Heat exchanger head is only 1.5' at 4 USgpm and
approximately 4' at 10 USgpm.
The minimum flow rate required through the heat exchanger is listed in Table 6 ,Table 6 , and
Table 6 . To ensure adequate water flow through the boiler under high-head / single zone
space heating conditions, a pressure activated bypass or other means of bypass must be
used on any load where the flow rate might drop below minimum requirements.
These boilers are designed to supply three different heating loads with temperatures within
the range 34°F to 180°F - to meet three separately piped loads. Use closely spaced tees to
connect each pumped "load" (e.g. DHW, baseboards or radiant floor) to the primary loop, or
employ the use of a hydraulic separator to isolate the boiler loop from the system and pipe the
system from the secondary side of the separator. Twoload systems may be piped with a
variant of parallel piping commonly used, including our unique dual side piping configuration.
Ensure that the pump is rated for the design circulating water temperatures; some pumps
have a minimum water temperature rating above the low temperature potential of the boiler.
Following installation, confirm the actual performance by measuring Δ°T (under high and low
flow conditions).
Check valves or thermal traps should be used to isolate both the supply and return piping for
each load - to avoid thermal siphoning and reverse flow.
To ensure adequate water flow through the boiler under high-head / single zone space
heating conditions, a pressure activated bypass or other means of bypass must be used on
any load where the flow rate might drop below minimum requirements.
Boilers can be connected directly to a floor of non-oxygen barrier polybutylene material
(PB tubing). For maintenance of warranty on such systems, all loops must be flushed
thoroughly, and a dirt separator or side stream filter must be installed. After the retrofit, a
separator / filter maintenance routine must be performed, with filter clearing after the first day,
first week, month, and annually thereafter. Ferrous fitting and pumps must not be used on
non-oxygen barrier tube systems.
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