Designer Guide

LOCHINVAR, LLC

300 MADDOX SIMPSON PKWY

LEBANON, TN 37090

www.lochinvar.com

Designer’s Guide / Knight XL Boiler

The purpose of System / Boiler Loop piping is to separate or “decouple” the system flow rate from

the boiler flow rate.

The System Loop will have its own dedicated “System Circulator”. This circulator will circulate

throughout the building. The Boiler Loop will have its own dedicated “Boiler Circulator”. This

circulator will pull from the system to flow into and out of the boiler. The Boiler circulator is field

supplied and must be sized for the head loss of the boiler and related pipe and fittings in the

Boiler Loop only.

BOILER CIRCULATOR REQUIREMENTS

Again, there will be a minimum of two pumps in a System / Boiler Loop. Both pumps are

provided by the installer. The boiler pump must be sized to provide adequate flow through the

boiler and the Boiler Loop piping. A Boiler Temperature Rise Chart is provided to assist in proper

pump selection. This table provides GPM and boiler head-loss at various temperature rises for

each model based on Btu/hr input. Pipe diameter and length are critical to ensure proper flow

through the boiler. The values listed on the table are based on a maximum 20 feet of pipe with 4

– 90° elbows and 2 – full port ball valves.

CIRCULATOR PUMP SPECIFICATIONS

1. Maximum operating pressure for the pump must exceed system operating pressure.

2. Maximum water temperature should not exceed the nameplate rating.

3. Cast iron circulators may be used in closed loop systems.

Reference Drawing A1 – Page ??

Reference Drawing A1 – Page 32.