Monessen Hearth Systems PH18NM, PH18NV, PH24NM, PH24NV, PH18PM Installation Manual

PH Gas Logs

INSTALLATION

BEFORE FULLY INSTALLING THE UNIT:

Turn OFF the gas supply to the replace or re-

•

box.

• Seal any fresh air vents and/or ash clean-out doors

located on the oor or wall of the replace. If left

unsealed, drafting may cause pilot outage or soot-

ing. Use a heat resistant sealant. Do not seal the

chimney ue damper.

Before installing in a solid fuel burning
fireplace, The chimney flue and firebox
must be cleaned of soot, creosote, ashes
and loose paint by a qualified chimney

WARNING

cleaner.

INSTALLING VENTED APPLICATIONS

Manual and millivolt controlled gas logs may be installed as

a vented decorative log set in compliance with ANSI Z21.60
and National Fuel Gas Code, Section 6.6 Since, the gas

logs are operated with the damper open, non-combustible

material and minimum mantel requirements do not apply.

NOTE: The use of a thermostat is prohibited in vented log

applications.

This appliance is for installation only in a solid
fuel burning replace (masonry replace or
manufactured fireplace) with a working
ue and constructed of noncombustible

material.

Exception: DO NOT install this appliance
in a factory-built fireplace that includes

WARNING

instructions stating that it has not been
tested or should not be used with unvented
gas logs. This log set may be installed as a

vented log set.

BEFORE INSTALLING THE APPLIANCE:

• Turn off gas supply to replace or rebox.

• Have the replace oor and chimney professionally

cleaned to remove ashes, soot, creosote or other

obstructions. Have this cleaning performed annually
after installation.

• Seal any fresh air vents or ash clean-out doors lo-

cated on oor or wall of replace. If not, drafting may
cause pilot outage or sooting. Use a heat-resistant
sealant. Do not seal chimney ue damper.

Install and operate the appliance as directed in this

manual.

DAMPER STOP INSTALLATION:

A damper stop must be provided with the unit. Contact your
dealer to obtain one. The damper stop must be installed as
shown in Figure 11 to prevent full closure of the replace
damper blade and provide a minimum 29 square inch ue
opening.

Damper
Stop

Damper

FP2538

Figure 11 ­Damper Stop Installation
(See Warning)

The replace and gas logs function as a
system. If the replace is spilling into the
room (check with a match or a smoke stick),
reposition the damper clamp until a positive
draft is obtained by opening the damper. If
negative pressure in home prevents having

WARNING

a positive draft, contact your dealer for

assistance.

PLACE AND SECURE APPLIANCE

You must secure the gas log heater to

the replace oor. If not, the entire unit

may move when you adjust the controls.
Movement of unit may cause shifting of
the gas logs which leads to sooting and

improper burning.

Special care is required if you are installing
the unit into a sunken replace. You must
raise the replace oor to allow access to

WARNING

gas log controls. This will insure adequate
air ow and guard against sooting. Raise
the replace oor using noncombustible
materials, as described in Placement in a

Fireplace with Restrictive Barrier on Page

7.

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Monessen • PH18/24 Installation/Owner's Manual • 65D2035 • Rev E • 01/19

INSTALLATION

PH Gas Logs

ASSEMBLY PROCEDURE

1. Center the gas log unit in the replace or rebox.

2. Install Grate: Insert longest middle grate bar in one of
the two square holes in control panel. Figure 12. Be sure
grate is centered. Sit horizontal bar inside two hooks
on front of control panel. Figure 12. Make certain front
feet of grate are located inside front edge of replace
or rebox.

3. Anchor holes are located on the ange of the unit. Figure

12. After centering the burner correctly, mark the hole
positions on the replace/rebox oor. Drill two (2) 5/32"

diameter holes approximately 11⁄2" deep.

4. Anchor the unit to the replace/rebox oor using the
screws provided. Figure 13.

Screws

Hole for
Grate Bar

Use new black iron or steel pipe. Internally
tinned copper or copper tubing can be
used per National Fuel Code, section 2.6.3,
providing gas meets hydrogen sulfide
limits, and where permitted by local codes.
Gas piping system must be sized to provide
minimum inlet pressure (Listed on Data
Plate) at the maximum ow rate (BTU/Hr).
Undue pressure loss will occur if the pipe

is too small.

CAUTION

A manual shutoff valve must be installed
upstream of the appliance. Union tee
and plugged 1/8" NPT pressure tapping
point should be installed upstream of the
appliance. Figure 13

Stainless
Flexible
Tube

To
Heater
Valve

Pipe

Possible Locations
for Pressure
Tapping Point

Middle
Grate Bar

Hooks for
Grate

Horizontal
Grate Bar

Figure 12 ­Install Grate and Secure Heater to Floor
of Fireplace/Firebox

Anchor
Hole

CONNECT THE GAS LINE

NOTICE: A qualied gas appliance installer must

connect the heater to the gas supply. Consult all local
codes.

Pipe
Coupling

Manual Shutoff
Valve

Figure 13 ­Gas Connection

Gas
Supply
Inlet

FP2371

IMPORTANT: Hold heater valve rmly with a wrench to
prevent movement when connecting to inlet pipe.

CHECK GAS TYPE: The gas supply must
be the same as stated on the heater’s rat­ing plate. If the gas supply is different, DO

NOT INSTALL THE HEATER. Contact your

WARNING

dealer for the correct model.

Connecting directly to an unregulated pro­pane/LPG tank can cause an explosion.

WARNING

Always use an external regulator for all propane/LPG
heaters and high pressure one to two-pound systems

only, to reduce the supply tank pressure to a maximum of

13" w.c. This is in addition to the internal regulator in the
heater valve.

Monessen • PH18/24 Installation/Owner's Manual • 65D2035 • Rev E • 01/19

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