LP-719 Rev. 000 Rel. 000 Date 6.25.20
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Figure 18 - Combi Boiler without Central Heating Circulator
NOTE:
In piping applications utilizing a single zone, it is recommended that the installer use flow / check valves with weighted seats at or near
the appliance to prevent gravity circulation.
NOTICE
Figure illustrates the basic plumbing requirements for a combi boiler installation without an external Central Heating circulator; the boiler’s
internal circulator delivers flow to the heating system. Application is limited to zone valve (or non-circulator) distribution systems with small flow
requirements (e.g. systems requiring no more than 9 gpm at 9 ft. of head pressure).
NOTES:
1. This drawing is meant to show system piping concept only. Installer is responsible for all equipment and detailing required by local codes.
2. The minimum pipe size of DHW piping should be ¾” diameter and CH piping should be 1” in diameter.
3. Circulators are shown with isolation flanges. The alternative is standard flanges with full port ball valves. Purge valves can be used with
circulator flanges as an alternative.
4. Install a minimum of 12 diameters of straight pipe upstream of all circulators.
5.
VERY IMPORTANT
– Minimum flow rates outlined in this manual (2 gpm) must be maintained through the heat exchanger to minimize
short cycling.
6. In a valve-based system, each heating zone has a zone valve which opens when that zone calls for heat. Each zone thermostat is wired to
its corresponding zone valve. Contacts in the zone valves provide a signal to the boiler to operate when there is a call for heat.
7.
Unit is equipped with built-in primary pump for the heating loop.
This pump is sized to ensure proper flow rate through the boiler
heat exchanger and related piping.
8. For direct (not primary / secondary) piping applications, it is required to install the expansion vessel on the return side of the boiler as
illustrated.
WARNING
!
The piping will not support the weight of the circulators. Refer to the circulator manufacturer’s instructions to properly support the circulator.
Failure to comply with these instructions could result in property damage, severe personal injury, or death.
For direct (not primary / secondary) piping applications, the expansion vessel must be
placed on the return side of the boiler as illustrated. Placement of flow resticting de-
vices, such as check valves, is prohibited between the boiler return and the expansion
vessel. Failure to place the expansion vessel as instructed, may result in the release of
the pressure relief valve, property damage, severe personal injury, or death.
WARNING
!
