Superior VFGL-24VSP-4, VFGL-24MSP-4, VFGL-24MSN-4, VFGL-28MSP-4, VFGL-18MSP-4 User Manual

INSTALLATION AND OPERATING INSTRUCTIONS

INSTALLER: Leave this manual with the appliance. CONSUMER: Retain this manual for future reference.

STANDARD SERIES

Unvented Gas Log Room Heaters

P/N 903623 REV. M 12/2007

MODELS

VFGL-18VSN-4 Series	VFGL-18MSN-4 Series*
VFGL-18VSP-4 Series	VFGL-18MSP-4 Series*
VFGL-24VSN-4 Series	VFGL-24MSN-4 Series*
VFGL-24VSP-4 Series	VFGL-24MSP-4 Series*
VFGL-28VSN-4 Series	VFGL-28MSN-4 Series*
VFGL-28VSP-4 Series	VFGL-28MSP-4 Series*

							WARNING: IMPROPER INSTALLATION, ADJUSTMENT, AL-
							TERATION, SERVICE OR MAINTENANCE CAN CAUSE IN-
							JURY OR PROPERTY DAMAGE. REFER TO THIS MANUAL.
			US				FOR ASSISTANCE OR ADDITIONAL INFORMATION CON-
							SULT A QUALIFIED INSTALLER, SERVICE AGENCY OR THE
							GAS SUPPLIER.
FOR USE ONLY WITH DECORATIVE TYPE UNVENTED ROOM							WARNING: DO NOT BUILD A WOOD FIRE. DO NOT BURN
HEATERS.							WOOD OR OTHER MATERIAL IN THESE APPLIANCES.
							CAREFULLY REVIEW THE INSTRUCTIONS SUPPLIED WITH
	WARNING: IF THE INFORMATION IN THIS MANUAL						THE DECORATIVE TYPE UNVENTED ROOM HEATER FOR
	IS NOT FOLLOWED EXACTLY, A FIRE OR EXPLO-						THE MINIMUM FIREPLACE SIZE REQUIREMENT.
	SIONMAYRESULTCAUSINGPROPERTYDAMAGE,						DO NOT INSTALL THE APPLIANCE IN THIS FIREBOX, UN-
	PERSONAL INJURY OR LOSS OF LIFE.						LESS THIS FIREBOX MEETS THE MINIMUM DIMENSIONS
							REQUIRED FOR THE INSTALLATIONS.
	FOR YOUR SAFETY: Do not store or use gasoline
	or other flammable vapors or liquids in the vicinity						This is an unvented gas-fired heater. It uses air
	of this or any other appliance.						(oxygen) from the room in which it is installed.
	FOR YOUR SAFETY: What to do if you smell gas:						Provisions for adequate combustion and ventila-
							tion air must be provided. Refer to Combustion
	•	DO NOT light any appliance.					and Ventilation Air Section, Page 3.
	•	DO NOT touch any electrical switches.					Due to high temperatures, the appliance should be located out
	• DO NOT use any phone in your building.
							of traffic and away from furniture or draperies.
	• Immediately call your gas supplier from a						Do not place clothing or other materials on or near this
		neighbor’s phone.
	Follow your gas suppliers instructions.						appliance.
	• If your gas supplier cannot be reached, call the						IMPORTANT: READ AND UNDERSTAND THESE INSTRUCTIONS
		fire department.					COMPLETELY BEFORE INSTALLING YOUR UNVENTED ROOM
							HEATER.

Installation and service must be performed by a quali-

*Note: Manual control models are also design certified for use as vented

fied installer, service agency or the gas supplier. gas log sets. 1

NOTE: DIAGRAMS & ILLUSTRATION NOT TO SCALE.

TABLE OF CONTENTS
General Information .........................	page	2
Inventory .........................................	page	2
Tools Required ................................	page	2
Important Safety Information ..........	page	2
Codes ..............................................	page	3
Combustion and Ventilation Air .......	page	3
Preinstallation ..................................	page	4
Clearances .......................................	page	4
Installation .......................................	page	6
Gas Pressure Check .........................	page	7
Flame Appearance ...........................	page	8
Operation .........................................	page	8
Cleaning and Servicing ....................	page	8
Replacement Parts ..........................	page	8
Optional Equipment/Accessories .....	page	9
Heater Specification Chart ...............	page 10
Heater Technical Detail Chart ...........	page 10
Troubleshooting Guide ....................	page 11
Operating Instructions – Manual .....	page 12
Operating Instructions – Millivolt ....	page 14
Replacement Parts List ....................	page 16

GENERAL INFORMATION

These Unvented Gas Log Room Heaters incorporate unitized ceramic fiber logs which glow realistically when the heater is operating.

The log sets covered in this document are manually controlled heater rated units. These units are equipped with either a standard manual gas valve or a millivolt gas valve. The control knob is set to the desired position, which maintains a continuous gas burning rate.

A spark ignition system (piezo) allows the gas pilot to be lit without the use of matches or batteries and permits operation of the heater during a power outage.

These heaters are fitted with a specially designed pilot utilizing an oxygen depletion sensor (ODS) which responds to the amount of oxygen available in the room and shuts the heater off before the oxygen level drops below 18%. The pilot can be relit only when fresh air is available. Refer to the Combustion and Ventilation Air section.

2

WARNING: THIS APPLIANCE IS FOR INSTALLATION ONLY IN A SOLID FUEL BURNING FIREPLACE WITH A WORKING FLUE OR AN APPROVED VENTLESS FIREBOX ENCLOSURE.

Minimum Fireplace (Firebox) Size

Log Set	Height	Depth	Width
18" Models	16"	14"	20" Front
			19" Rear
24" Models	16"	14"	35" Front
			27" Rear
28" Models	16"	14"	38" Front
			30" Rear

Table 1

Do not install these Unvented Gas Log Room Heaters in a bedroom or a bathroom as all units exceed maximum allowable BTU/hr input of 10,000.

Check the inventory list to be sure that you have all the necessary parts in usable condition. Also check for concealed damage.

Inventory

Unvented gas log room heater Two (2) screws

Bag of decorative volcanic rock Ceramic fiber log set

Installation and Operating Instructions

Tools and Supplies Normally Required

External regulator (Propane models only) Manual shut-off valve

Sediment trap

Piping complying with local codes Pipe compound

Pipe wrench Tee joint Screwdriver

IMPORTANT SAFETY INFORMATION

INSTALLER: PLEASE LEAVE THESE INSTRUCTIONS WITH THE OWNER.

OWNER: PLEASE RETAIN THESE INSTRUCTION FOR FUTURE REFERENCE

IMPORTANT: READ THESE INSTALLATION INSTRUCTIONS CAREFULLY BEFORE INSTALLING OR TRYING TO OPERATE THIS HEATER.

NOTE: DIAGRAMS & ILLUSTRATION NOT TO SCALE.

WARNING: FAILURE TO COMPLY WITH THE INSTALLATION AND OPERATING INSTRUCTIONS PROVIDED IN THIS DOCUMENT WILL RESULT IN AN IMPROPERLY INSTALLED AND OPERATING APPLIANCE, VOIDING ITS WARRANTY. ANY CHANGE TO THIS APPLIANCE AND/OR ITS OPERATING CONTROLS IS DANGEROUS. IMPROPER INSTALLATION OR USE OF THIS APPLIANCE CAN CAUSE SERIOUS INJURY OR DEATH FROM FIRE, BURNS, EXPLOSION OF CARBON MONOXIDE POISONING.

Carbon Monoxide Poisoning: Early signs of carbon monoxide poisoning are similar to the flu with headaches, dizziness and/or nausea. If you have these signs, obtain fresh air immediately. Turn off the gas supply to the appliance and have it serviced by a qualified professional, as it may not be operating correctly.

•Due to high temperatures, the heater should be located out of traffic and away from furniture and draperies.

•Children and adults should be alerted to the hazard of high surface temperature and should stay away to avoid burns or clothing ignition.

•Young children should be carefully supervised when they are in the same room with the heater.

•Do not place clothing or other flammable material on or near the heater.

•Any safety screen or guard removed for servicing the heater must be replaced prior to operating the heater.

•Installation and repair should be done by a qualified service person. The heater should be inspected before use and at least annually by a professional service person. More frequent cleaning may be required due to excessive lint from carpeting, bedding material, etc. It is important that control compartments, burners and circulating air passageways of the heater be kept clean.

•Allow the heater to cool before servicing. Always shut off the gas to the heater while performing service work.

•Do not install the heater in a bedroom or bathroom.

•The installation must conform with local codes or, in the absence of local codes with the National Fuel Gas Code, ANSI Z223.1.

•The heater and its individual shut-off valve must be disconnected from the gas supply piping system while performing any tests of the gas supply piping system at pressures in excess of 1/2 psig.

•The heater must be isolated from the gas supply piping system by closing its individual manual shut-off valve during any pressure testing of the gas supply piping system at test pressures equal to or less than 1/2 psig.

•Keep heater area clear and free from combustible materials, gasoline and other flammable vapors and liquids.

•Do not use this heater if any part has been under water. Immediately call a qualified service technician to inspect the room heater and to replace any part of the control system and any gas control which has been under water.

•Input ratings are shown in BTU per hour and are for elevations up to 4,800 feet. Do not install this heater at an elevation above 4,800 feet if the gas supply has not been derated for that elevation. Consult your local gas supplier. (For operation at elevations above 4,800 feet, equipment ratings shall be reduced at the rate of 4 percent for each 1,000 feet above sea level before selecting appropriately sized equipment.)

•Ensure that the heater is clean when operating. Excessive dust accumulation on the burner and/or logs will increase the amount of carbon monoxide formation and could lead to carbon monoxide poisoning and/or death.

CODES

Adhere to all local codes or in their absence the latest edition of The National Fuel Gas Code ANSI Z223.1 or NFPA54 which can be obtained from The American National Standards Institute, Inc. (1430 Broadway, New York, NY, 10018) or National Fire Protection Association, Inc. (Batterymarch Park, Quincy, MA, 02269).

Massachusetts And New York Requirements

These appliances are approved for installation in the following USA locations listed in the following:

Massachusetts:

These fireplaces are approved for installation in the US state of Massachusetts if the following additional requirements are met-

•Installation and repair must be done by a plumber or gas fitter licensed in the Commonwealth of Massachusetts.

•The flexible gas line connector used shall not exceed 36 inches (92 centimeters) in length.

•The individual manual shut-off must be a T- handle type valve.

•Vent-Free appliances may NOT be installed in bedrooms or bathrooms.

•A working smoke detector must be installed in the area where vent-free appliances are installed.

Seller of unvented propane or natural gasfired supplemental room heaters shall provide to each purchaser a copy of 527 CMR 30 upon sale of the unit.

New York:

These fireplaces are approved for installation in the US state of New York, but not in New York city.

State or local codes may only allow operation of this appliance (manual version only) in a vented configuration. Check your state or local codes.

Superior Unvented Gas Log Room Heaters are certified by OMNI to ANSI Z21.11.2 standard. These gas log room heaters may be used as a space heat source for a room in conjunction with an approved unvented firebox. Additionally, manually controlled units are design certified by OMNI to ANSI 21.60 as a vented gas log set.

As such, manually controlled units may be used as a vented gas log set in any wood-burning fireplace that has been properly constructed to code, and in the case of factory built fireplaces, installed in compliance with manufacturers listing and installation instruction.

Use of the manually controlled log sets covered by this manual in a properly vented woodburning fireplace which has had the damper blocked open as detailed in these installation instructions preclude consideration of the combustion and ventilation air and clearance to combustible restrictions discussed herein.

NOTE: DIAGRAMS & ILLUSTRATION NOT TO SCALE.

COMBUSTION AND VENTILATION AIR

These heaters shall not be installed in a confined space. The heater may be located in unusually tight construction provided the space is unconfined, or if confined, is provided with two permanent openings communicating directly with an additional room(s) of sufficient volume so that the combined volume of all connected spaces meets the criteria for an unconfined space, (National Fuel Gas Code ANSI Z223.1 (latest edition), Section 5.3). Generally 50 ft 3 per 1,000 BTU input of all operating appliances in the space.

The National Fuel Gas Code defines a confined space as a space whose volume is less than 50 ft 3 per 1,000 BTU/Hr (4.8 m3 per kw) of the aggregate input rating of all appliances installed in that space and an unconfined space as a space whose volume is not less than 50 ft 3 per 1,000 BTU/Hr (4.8 m3 per kw) of the aggregate input rating of all appliances installed in that space. Rooms communicating directly with the space in which the appliances are installed, through openings not furnished with doors, are considered a part of the unconfined space.

Unusually tight construction is defined as construction where:

a.wall and ceilings exposed to the outside atmosphere have a continuous water vapor retarder with a rating or one perm or less with openings gasketed or sealed, and

b.weather stripping has been added on operable windows and doors, and

c.caulking or sealants are applied to areas such as joints around window and door frames, between sole plates and floors, between wallceiling joints, between wall panels, at penetrations for plumbing, electrical, and gas lines, and at other openings.

Use the following equations to determine if you have a confined or unconfined space.

1.Determine the volume of space — ft 3.

Length x Width x Height = _____ ft 3 (Include adjoining rooms with doorless passageways or ventilation grills between rooms.)

Example: 24' (L) x 16' (W) x 8' (H) = 3072 ft 3

3

2.Divide the volume of space by 50 ft 3 to determine the maximum BTU/Hr the space can support.

______ (volume of space – ft 3)/ 50 ft 3 = (Maximum BTU/Hr the space can support)

Example: 3072 ft 3 / 50 ft 3 = 61.44

or 61,440 BTU/Hr the space can support.

3.Add the BTU/Hr of all the fuel burning appliances in the space.

Vent-Free heater	_______	BTU/Hr
Gas appliance #1*	_______	BTU/Hr
Gas appliance #2	+ _______	BTU/Hr
Total = _______		BTU/Hr
Example:
Vent-free heater	32,000	BTU/Hr
Gas appliance #1	35,000	BTU/Hr
(water heater)
Total = 67,000		BTU/Hr

* Do not include direct-vent gas appliances. Direct-vent is sealed combustion and draws combustion air from the outdoors.

4. Compare the maximum BTU/Hr the space can support with the actual amount of BTU/ Hr used.

_________	BTU/Hr
	(max. the space can support)
_________	BTU/Hr
	(actual amount of BTU/Hr used)
Example:
61,440	BTU/Hr
	(max. the space can support)
67,000	BTU/Hr
	(actual amount of BTU/Hr used)

The space in the previous example is a confined space because the actual BTU/Hr used is more than the maximum BTU/Hr the space can support. You must provide additional fresh air.

Your options are:

a.Rework equations adding the space of adjoining room(s). If the extra volume provides an unconfined space, then remove door or add ventilation grills between rooms. Refer to National Fuel Gas Code, ANSI Z223.1, Section 5.3.

4

b.Vent room directly to the outdoors. Refer to National Fuel Gas Code, ANSI Z223.1, Section 5.3.

c.Install a lower BTU/Hr heater, such as a 24,000 BTU/Hr, to make the area an unconfined space.

If the actual BTU/Hr used is less than the maximum BTU/Hr the space can support, then the space is an unconfined space. You will need no additional fresh air ventilation for an unconfined space.

WARNING: IF THE AREA IN WHICH THE HEATER MAY BE OPERATED IS SMALLER THAN THAT DEFINED AS AN UNCONFINED SPACE, PROVIDE ADEQUATE COMBUSTION AND VENTILATION AIR BY ONE OF THE METHODS DESCRIBED IN THE NATIONAL FUEL GAS CODE, ANSI Z223.1, SECTION 5.3 OR APPLICABLE LOCAL CODES.

PREINSTALLATION

WARNING: 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 CLEANER.

Note: Illustrations shown in this manual reflect “typical” installations with nominal dimensions and are for reference only. Actual installations may vary due to individual design preferences. However, always maintain minimum clearances to combustible materials and do not violate any specific installation requirements. Refer to Figures 1 through 7 for clearances.

Note: The following steps represent the normal sequence of installation. Each installation is unique, however, and might require a different sequence.

When local codes require the damper to be fixed open, a damper stop must be installed to prevent full closure of the fireplace damper and provide a minimum 29 square inch flue opening at all times. Refer to accessories for damper clamp.

NOTE: DIAGRAMS & ILLUSTRATION NOT TO SCALE.

If damper clamp is not available, the damper may be fixed open in the following manner. Drill a hole in the end of the damper. Screw in a bolt of sufficient size and adjust to provide the minimum 29 square inches of flue opening.

CAUTION: HEATERS CREATE WARM AIR CURRENTS. THESE CURRENTS MOVE HEAT TO WALL SURFACES NEXT TO HEATER. INSTALLING HEATER NEXT TO VINYL OR CLOTH WALL COVERINGS OR OPERATING HEATER WHERE IMPURITIES IN THE AIR (SUCH AS TOBACCO SMOKE) EXISTS, MAY DISCOLOR WALLS.

•Turn off gas supply to the fireplace or firebox.

•Position heater in fireplace or firebox.

•Connect gas line.

•Secure heater.

•Assemble logs and test flame.

•Sprinkle volcanic rock over base plate in front of and below the main burner.

Check Gas Type

This heater can only be connected to the gas type specified on the heater rating plate. This heater can not be modified in the field for a different gas type. If the gas supply differs, DO NOT INSTALL the heater. Contact your dealer to obtain the correct heater.

CLEARANCES

WARNING: DO NOT INSTALL THIS GAS HEATER:

•IN SLEEPING QUARTERS, BATHROOMS, A MOBILE HOME, OR A RECREATIONAL VEHICLE.

•WHERE CURTAINS, FURNITURE, CLOTHING OR OTHER FLAMMABLE OBJECTS ARE LESS THAN 42" FROM THE FRONT OF THE GAS HEATER.

•IN HIGH TRAFFIC AREAS.

•IN WINDY OR DRAFTY AREAS.

Ensure the minimum clearances shown in Figures 1 through 7 are maintained. Left and right clearances are determined when facing the front of the heater.

Noncombustible Material Requirements with No Mantel Installed

(A) Noncombustible Material Measurement	Requirements for Safe Installation
12" or more	Adjustable canopy not required.
8" minimum to 12"	Install adjustable canopy, P/N 053752
	(Figure 3 ).
Less than 8"	Extend noncombustible material to at least
	8" and install adjustable canopy (Figure 3 ).
	or
	Extend noncombustible material to a height
	of at least 12".

Table 2

Noncombustible Material Heights and Mantel Location

	Requirements for Safe Installation
	with Wood Mantel, Shelf or
Noncombustible Material Measurement	Other Combustible Projection
12" or more	Adjustable canopy not required. Observe pro-
	files shown in Figure 4.
8" minimum to 12"	Install adjustable canopy and observe pro-
	files shown in Figure 5.
	or
	Extend heat resistant material to at least 12"
	and observe profiles shown in Figure 4.

Table 3

Follow these instructions carefully to ensure safe installation. Failure to follow these requirements may create a fire hazard.

Step 1. Sidewall Clearances: The sides of the fireplace opening must be at least 16" from any combustible side wall (Figure 1 ).

42"

Min.

16"

Min.

Figure 1

Step 2. Ceiling Clearance: The ceiling must be at least 42" from the top of the heater opening (Figure 1 ).

Step 3. Noncombustible materials (minimum requirements): To install the room heater without wood mantels, shelves or other combustible projections directly above the opening of the fireplace (firebox) refer to Figure 2 and Table 2. Note that at least 8" of noncombustible material must be installed above the heaters described in this manual.

Noncombustible materials, such as slate and marble, must be at least 1/2" thick.

Noncombustible

Material

A

Heater in Fireplace

or Firebox

Figure 2

NOTE: DIAGRAMS & ILLUSTRATION NOT TO SCALE.

8" or More of Noncombustible Material

Adjustable

Canopy

Heater in Fireplace

or Firebox

Figure 3

Step 4. Wood mantel, shelf or combustible projection requirements: To install a wood mantel, shelf or other combustible projection directly above the fireplace (firebox), refer to Table 3 and to Figures 4 and 5 for installation profiles.

If your mantel profile is unsafe, you may either:

•Raise the mantel to an acceptable height, or

•Remove the mantel.

Example: The bottom of the mantel may project from the wall a maximum of 2-1/2" at a minimum of 28" above the opening. The top shelf of the mantel may project a maximum of 6" at a minimum of 34-1/2" above the opening.

10" Ceiling 8"

6" 2-1/2" 42"

38-5/8"

34-1/2"

28"

Heat Resistant

Material

12"

Figure 4

5

Example: The bottom of the mantel may project from the wall a maximum of 2-1/2" at a minimum of 8" above the opening. The top shelf of the mantel may project a maximum of 6" at a minimum of 14-1/2" above the opening.

12"

	10"
	8"	26"
	6"
		22-1/2"
	2-1/2"
		18-5/8"
	8"	14-1/2"
	Min.

Hood (Canopy)

Heat Resistant

Material

Figure 5

Step 5. Floor clearance: If combustible flooring materials, such as carpeting or asphalt tile, are to be located within 14" of the fireplace or firebox opening, the room heater base must be at least 5" above the combustible flooring material (Figure 6 ).

Combustible

Material

Combustible

Material

5" Min.

Figure 6

The room heater base may be lower than 5" above the combustible flooring materials if the combustible flooring materials are more than 14" from the fireplace or firebox opening (Figure 7 ).

Combustible

Material

Can be less than 5"

14" Min.

(Both Sides Of Opening)

Figure 7

6

INSTALLATION

WARNING: DO NOT ALLOW FANS TO BLOW DIRECTLY INTO THE FIREPLACE. AVOID ANY DRAFTS THAT ALTER BURNER FLAME PATTERNS.

WARNING: DO NOT USE A BLOWER INSERT, HEAT EXCHANGER INSERT OR OTHER ACCESSORY NOT APPROVED FOR USE WITH THIS HEATER.

This appliance must not be operated without a fireplace screen installed. Fireplace screens must not impair the free flow of combustion air to the appliance.

Do not burn solid fuels in any fireplace equipped with this listed unvented gas room heater.

WARNING: INSTALLED DECORATIVE GLASS DOOR ENCLOSURES MUST BE FULLY OPENED WHEN OPERATING THIS LISTED UNVENTED GAS ROOM HEATER.

Any outside air ducts and/or ash dumps that are part of the original solid fuel burning fireplace system must be fully closed and sealed at the time of installation of this listed unvented gas room heater.

WARNING: SPECIAL CARE IS REQUIRED IF YOU ARE INSTALLING THE UNIT INTO A SUNKEN FIREPLACE. YOU MUST RAISE THE FIREPLACE FLOOR TO ALLOW ACCESS TO GAS LOG CONTROLS. THIS WILL INSURE ADEQUATE AIR FLOW AND GUARD AGAINST SOOTING. RAISE THE FIREPLACE FLOOR USING NONCOMBUSTIBLE MATERIALS.

A qualified gas appliance installer must install this heater.

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 dealer for the correct model.

Step 1. Placement of Heater – Center the heater in the fireplace or firebox. Make certain the grate front feet sit inside the front edge of the fireplace or firebox.

NOTE: DIAGRAMS & ILLUSTRATION NOT TO SCALE.

To avoid any movement of the heater during operation, attach the grate to the floor of the fireplace or firebox using the screws provided. Slots along the back flange of the log set are provided. After centering the grate correctly, mark the positions of the bottom of the slots on the fireplace/firebox floor. Drill two (2) 9/64" diameter holes with masonry drill approximately 1/2" deep.

Preliminarily anchor the grate to the fireplace/ firebox floor with the two (2) screws provided (Figure 8 ). Loosen screws and proceed with the installation.

Alternate

Location Anchor Screw

(Both Sides)

Figure 8

Step 2. Connecting Gas Line – A qualified gas appliance installer must connect the gas room heater to the gas supply.

Consult all local codes.

Route gas line using techniques and materials prescribed by local and/or national codes. Only use pipe of ¹⁄" or greater diameter to allow full gas volume to the gas fireplace. Undue pressure loss will occur if the pipe is too small.

An ANSI approved manual shut-off valve and union must be installed upstream of the heater within the fireplace cavity when rigid pipe is used.

Ensure that a sediment trap is installed upstream of the heater within the structures piping system to prevent moisture and contaminants from passing through the pipe to the heater controls and burners (Figure 9 ). Failure to do so could prevent the heater from operating reliably.

IMPORTANT: HOLD HEATER REGULATOR WITH A WRENCH TO PREVENT MOVEMENT WHEN CONNECTING TO INLET PIPING

An external regulator must be used on all propane (L.P.G.) heaters, in addition to the regulator fitted to the heater, to reduce the supply tank pressure to 13" w.c. (maximum).