LP-293 Rev. 9.24.15
4
Table of Contents
Part 1 - General Safety Information 5
A. Improper Combustion 6
B. Gas 6
C. When Servicing the Boiler 6
D. Boiler Water 6
E. Freeze Protection 6
Part 2 - Before You Start 6
A. What’s in the Box 6
B. How the Boiler Operates 7
C. Optional Equipment 7
Part 3 - Prepare the Boiler 8
A. Locating the Boiler 8
B. Flooring 9
C. Leveling 9
D. Clearances for Service Access 9
E. Residential Garage Installation 9
F. Exhaust Vent and Intake Pipe 9
1. Direct Vent of Exhaust and Intake 10
2. Indoor Combustion Air in Conned or Unconned Space
10
G. Prevent Combustion Air Contamination 10
H. Removing a Boiler from a Common Vent System 11
I. Water Chemistry Requirements* 11
Part 4 - Piping 14
A. General Plumbing Information 14
B. Relief Valve 14
C. Backow Preventer 14
D. Potable Expansion Tank 15
E. Circulators 15
F. Hydronic Piping with Circulators, Zone Valves, and
Multiple Boilers 15
G. Circulator Sizing 15
H. Check / Control Water Chemistry 17
I. Plumbing 18
J. Fill and Purge Heating System 18
K. Freeze Protection Fluids 18
L. Zoning with Zone Valves 19
M. Zoning with Circulators 19
The CSD-1 ASME Code, Section CW-400 requires that hot
water heating and supply boilers have a) a UL 353 temperature
control device, b) at least one (1) temperature-actuated
control to shut o the fuel supply when system water reaches
The hydronic supply and return connections of these
products are for installation in closed loop systems ONLY!
Use of this product in any manner other than described in this
manual may result in premature product failure, substantial
property damage, severe personal injury, or death. Damage or
failure of this product (or the system in which it is installed) due
to unauthorized use IS NOT COVERED BY WARRANTY.
IMPORTANT
In accordance with Section 325 (f) (3) of the Energy Policy
and Conservation Act, HTP, Inc. has provided this boiler with
multiple features designed to save energy by reducing the
boiler water temperature as heating load decreases.
These features include:
• A modulatingcombustionsystem that adjusts ring
rate based on heat demand.
• Adjustment of boiler set point based on inferred heat
load as determined by an outdoor sensor. The outdoor
sensor is supplied by HTP, Inc. with this boiler.
• This boiler does not include a standing pilot.
• This boiler is designed and shipped to assure the
highest eciency operation possible. Such high
eciencyisachievedbylimitingheatingcircuitwater
temperature to 140°F when there is no anticipated
heat load, based upon the outdoor sensor and the
Outdoor Reset Curve (sensor response curve) in the
boiler software.
• This feature may be over-ridden as described below in
specicinstallations:
• The boiler control is equipped with an outdoor sensor
override for use with building management systems
or in cascaded systems (for systems with total input of
300,000 BTU/hr or greater).
See statement below for an important notice on the use of
the override.
IMPORTANT
In accordance with Section 325 (f) (3) of the Energy Policy and
Conservation Act, this boiler is equipped with a feature that
saves energy by reducing the boiler water temperature as
the heating load decreases. This feature is equipped with an
override which is provided primarily to permit the use of an
external energy management system that serves the same
function. THIS OVERRIDE MUST NOT BE USED UNLESS AT
LEAST ONE OF THE FOLLOWING CONDITIONS IS TRUE:
• An external energy management system is installed
that reduces the boiler water temperature as the
heating load decreases.
• This boiler is not used for space heating.
• This boiler is part of a modular or multiple boiler
system having a total input of 300,000 BTU/hr or
greater.
• This boiler is equipped with a tankless coil.
a preset operating temperature, c) a high temperature limit
control that prevents the water temperature from exceeding
the maximum allowable temperature by causing a safety
shutdown and lockout, and d) its own sensing element and
operating switch.
The temperature control system integrated into the 926
control provided with this heating appliance complies with
the requirements of CSD-1 Section CW-400 as a temperature
operation control. The control monitors the temperature
dierence between the inlet and the outlet sensor, which is
aected by boiler water ow. If this temperature dierence
exceeds 55°F (typically because of low water ow or very low
heat load), the control will reduce the maximum fan speed.
If the temperature dierence exceeds 60°F, the control
will eectively sense there is little or no water ow or heat
load and shut the boiler down. The controller will restart
automatically once the temperature dierence has dropped
below 55°F and the minimum o time (anti-cycle time) has
expired. In addition, if the control senses that the outlet water
temperature has reached 210°F, the boiler is put into a hard
lockout and requires manual reset to restart.
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