U.S. Boiler Company V8H SERIES Service manual

110218-01 - 3/20
9700609
Installation, Operating and Service Instructions for
V8H Residential Water
TO THE INSTALLER:
Affix these instructions adjacent to boiler.
TO THE CONSUMER:
Retain these instructions for future reference.
For service or repairs to boiler, call your heating contractor. When seeking information on boiler, provide
Boiler Model Number and Serial Number as shown on Rating Label.
• Water Boiler
•Natural Draft
•Oil-Fired
Models:
•V8H3WE
•V8H4WE
•V8H5WE
•V8H6WE
•V8H7WE
• V8H3WEH
• V8H4WEH
• V8H5WEH
• V8H6WEH
• V8H7WEH
Manual Contents Page
1. Dimensional Description, Specification &
Dimensional Data .....................4
2. Pre-installation .......................8
3. Knock Down Boiler Assembly ..........10
4. Packaged Boiler Assembly ............17
5. Water Boiler Piping & Trim .............21
6. Tankless & Indirect Water Heater Piping..25
7. Venting & Air Intake Piping ............27
8. Electrical ...........................31
9. Oil Piping...........................36
10. System Start-Up .....................38
11. Operating...........................41
12. Service and Maintenance .............51
13. Boiler Cleaning .....................53
14. Troubleshooting .....................55
15. Service Parts .......................58
16. Burner Specifications ................64
Appendix .............................65
• V8H3WE-T
• V8H4WE-T
• V8H5WE-T
• V8H6WE-T
• V8H7WE-T
TM

2110218-01 - 3/20
V8H Installation & Service Manual
All boilers must be installed in accordance with National, State and Local Plumbing,
Heating and Electrical Codes and the regulations of the serving utilities. These
Codes and Regulations may differ from this instruction manual. Authorities having
jurisdiction should be consulted before installations are made.
In all cases, reference should be made to the following Standards:
USA BOILERS
A. Current Edition of American National Standard ANSI/NFPA 31, “Installation of Oil
Burning Equipment”, for recommended installation practices.
B. Current Edition of American National Standard ANSI/NFPA 211, “Chimneys, Fire
places, Vents, and Solid Fuel Burning Appliances”, For Venting requirements.
C. Current Edition of American Society of Mechanical Engineers ASME CSD-1,
“Controls and Safety Devices for Automatically Fired Boilers”, for assembly and
operations of controls and safety devices.
D. All wiring on boilers installed in the USA shall be made in accordance with the
National Electrical Code and/or Local Regulations.
NOTICE This boiler has a limited warranty, a copy of which is included with this boiler. The warranty for this boiler
is valid only if the boiler has been installed, maintained and operated in accordance with these instructions.
Surface rust on cast iron sections may be attributed to the manufacturing process as well as condensation
during storage. Surface rust is normal and does not affect the performance or longevity of a boiler.
IMPORTANT INFORMATION - READ CAREFULLY
NOTICE: Indicates special instructions on
installation, operation, or service which are
important but not related to personal injury
hazards.
DANGER
Indicates a hazardous situation that, if not
avoided, will result in death or serious injury.
CAUTION
Indicates a hazardous situation that, if not
avoided, could result in minor or moderate
injury.
WARNING
Indicates a hazardous situation that, if not
avoided, could result in death or serious injury.
! !
!
The following terms are used throughout this manual to bring attention to the presence of hazards of various
risk levels, or to important information concerning product life.

3
110218-01 - 3/20
V8H Installation & Service Manual
DANGER
DO NOT store or use gasoline or other flammable vapors or liquids in the vicinity of this or any other
appliance.
WARNING
Improper installation, adjustment, alteration, service or maintenance can cause property damage, personal
injury or loss of life. Failure to follow all instructions in the proper order can cause personal injury or death.
Read and understand all instructions, including all those contained in component manufacturers manuals
which are provided with the boiler before installing, starting-up, operating, maintaining or servicing this boiler.
Keep this manual and literature in legible condition and posted near boiler for reference by owner and service
technician.
• This boiler requires regular maintenance and service to operate safely. Follow the instructions contained in
this manual.
• Installation, maintenance, and service must be performed only by an experienced, skilled and knowledgeable
installer or service agency.
• All heating systems should be designed by competent contractors and only persons knowledgeable in the
layout and installation of hydronic heating systems should attempt installation of any boiler.
• Installation is not complete unless a pressure relief valve is installed into the tapping located on top left corner
of front section- See Piping and Trim Sections of this manual for details.
• It is the responsibility of the installing contractor to see that all controls are correctly installed and are operating
properly when installation is complete including verifying that the limit sensor is fully installed (seated in bottom
of Well).
• Failure to properly install Limit Sensor may result in property damage, personal injury or loss of life due to
elevated operating temperatures and/or pressures.
• This boiler is suitable for installation on combustible flooring. Do not install boiler on carpeting.
• Do not tamper with or alter the boiler or controls.
• Inspect flueways at least once a year - preferably at the start of the heating season. The inside of
the combustion chamber, the vent system and boiler flueways should be cleaned if soot or scale has
accumulated.
• When cleaning this boiler, DO NOT damage combustion chamber liner and/or rear target wall. If damaged,
combustion chamber insulation must be replaced immediately.
• Oil Burner and Controls must be checked at least once a year or as may be necessitated.
• Do not operate boiler with jumpered or absent controls or safety devices.
• Do not operate boiler if any control, switch, component, or device has been subject to water.
• Boiler materials of construction, products of combustion and the fuel contain alumina, silica, heavy metals,
carbon monoxide, nitrogen oxides, aldehydes and/or other toxic or harmful substances which can cause
death or serious injury and which are known to the state of California to cause cancer, birth defects and other
reproductive harm. Always use proper safety clothing, respirators and equipment when servicing or working
nearby the boiler.
!
!

4110218-01 - 3/20
V8H Installation & Service Manual
The V8H Series boiler is a cast iron oil-fired water
boiler designed for closed forced circulation heating
systems. This boiler must be vented by natural draft
into a fireclay tile-lined masonry chimney or chimney
constructed from type L vent or a factory built
chimney that complies with the type HT requirements
of UL103. An adequate supply of air for combustion,
ventilation and dilution of flue gases must be available
in the boiler room.
Water Boilers
The V8H Series water boiler uses an Intelligent Oil
Boiler Control (boiler control). The boiler control
replaces the traditional electronic aquastat and
circulator relays and adds energy saving thermal
purge features. Energy is saved by starting the
circulator and delaying the burner start when
there is residual heat available in the boiler. A
Warm Start Intelligent Oil Boiler Control (Warm
Start Boiler Control) is included with a tankless
heater option to generate domestic hot water.
1Product Description, Specification and Dimensional Data
WARNING
This boiler contains very hot water under high pressure. Do not unscrew any pipe fittings nor attempt to
disconnect any components of this boiler without positively assuring the water is cool and has no pressure.
Always wear protective clothing and equipment when installing, starting up or servicing this boiler to prevent
scald injuries. Do not rely on the pressure and temperature gauges to determine the temperature and
pressure of the boiler. This boiler contains components which become very hot when the boiler is operating.
Do not touch any components unless they are cool.
• High water temperatures increase the risk of scalding injury. If this boiler is equipped with a tankless heater
for domestic water supply, a flow regulator and automatic mixing valve must be installed properly in tankless
heater piping. See Piping and Trim Sections of this manual for details.
• This boiler must be properly vented and connected to an approved vent system in good condition. DO NOT
operate boiler with the absence of an approved vent system.
• This boiler needs fresh air for safe operation and must be installed so there are provisions for adequate
combustion and ventilation air.
• A clean and unobstructed chimney flue is necessary to allow noxious fumes that could cause injury or loss of
life to vent safely and will contribute toward maintaining the boiler's efficiency.
• This boiler is supplied with controls which may cause the boiler to shut down and not re-start without service.
If damage due to frozen pipes is a possibility, the heating system should not be left unattended in cold
weather; or appropriate safeguards and alarms should be installed on the heating system to prevent damage
if the boiler is inoperative.
• This boiler is designed to burn No. 2 fuel oil only. DO NOT use gasoline, crankcase drainings, or any oil
containing gasoline. Never burn garbage or paper in this boiler. DO NOT convert to any solid fuel (i.e. wood,
coal). DO NOT convert to any gaseous fuel (i.e. natural gas, LP). All flammable debris, rags, paper, wood
scraps, etc., should be kept clear of the boiler at all times. Keep the boiler area clean and free of fire hazards.
• All boilers equipped with burner swing door have a potential hazard which if ignored can cause severe
property damage, personal injury or loss of life. Before opening swing door, turn off service switch to boiler to
prevent accidental firing of burner outside the combustion chamber. Be sure to tighten swing door fastener
completely when service is completed.
!

5
110218-01 - 3/20
V8H Installation & Service Manual
Table 1A: Dimensional Data (See Figures 1A thru 1D)
Table 1B: Rating Data
Boiler
Model
Burner
Capacity
Heating
Capacity(2)
AHRI
NET
Ratings
(3)
AFUE
%
Minimum Chimney
Requirements
GPH MBH (1) MBH Water
MBH
Round
in Dia.
Rectangle
In. x In.
Height
Ft.
V8H3WE 1.00 140 120 104 86.0 6 8 x 8 15
V8H4WE 1.20 170 148 129 86.1 6 8 x 8 15
V8H5WE 1.65 231 200 174 86.0 7 8 x 8 15
V8H6WE 1.90 266 230 200 86.0 7 8 x 8 15
V8H7WE 2.10 294 255 222 86.1 8 8 x 8 15
(1) MBH refers to thousands of BTU per hour.
(2) Based on standard test procedure prescribed by the United States Department of Energy at combustion
conditions of 13.0% CO2.
(3) Net AHRI Ratings are based on piping and pickup allowance of 1.15 for water.
1Product Description, Specification and Dimensional Data (continued)
Boiler Series
Dimensions See Fiures 1A thru 1D Water Content
- Gallons
Approximate
Shipping
Weight (LB.)
"A" "B" "C"
V8H3 17-1/8" 9-1/8" 6" 12.8 542
V8H4 22-1/8" 11-5/8" 6" 15.7 634
V8H5 27-1/8" 14-1/8" 7" 18.5 726
V8H6 32-1/8" 16-5/8" 7" 21.4 818
V8H7 37-1/8" 19-1/8" 8" 24.2 910
NOTE 1: Maximum working Pressure: Water: 30 PSI Shipped From Factory (Std.), 40 PSI Optional, 50 PSI Optional

6110218-01 - 3/20
V8H Installation & Service Manual
Figure 1A: Water Boiler without Tankless Heater
1Product Description, Specification and Dimensional Data (continued)

7
110218-01 - 3/20
V8H Installation & Service Manual
Figure 1B: Water Boiler with Front Tankless Heater
1Product Description, Specification and Dimensional Data (continued)

8110218-01 - 3/20
V8H Installation & Service Manual
Figure 2: Minimum Installation Clearances To Combustible Materials (Inches)
A. INSPECT SHIPMENT carefully for any signs of
damage.
1. All equipment is carefully manufactured,
inspected and packed. Our responsibility
ceases upon delivery of crated boiler to the
carrier in good condition.
2. Any claims for damage or shortage in shipment
must be filed immediately against the carrier
by the consignee. No claims for variances
from, or shortage in orders, will be allowed by
the manufacturer unless presented within sixty
(60) days after receipt of goods.
B. LOCATE BOILER in front of final position before
removing crate. See Figures 1A and 1B.
1. LOCATE so that vent pipe connection to
chimney will be short and direct.
2. BOILER IS SUITABLE FOR INSTALLATION
ON COMBUSTIBLE FLOOR. Boiler cannot be
installed on carpeting.
3. FOR BASEMENT INSTALLATION, provide a
solid elevated base, such as concrete, if floor
is not level, or if water may be encountered on
floor around boiler.
4. PROVIDE SERVICE CLEARANCE of at least
24” clearance from front jacket panel for
servicing and removal of front tankless heater.
If boiler is equipped with a rear tankless heater,
provide at least 24" service clearance on the
right side of the boiler. Boiler flueways may be
cleaned either from the top or from the right
side. Provide at least 24" clearance from either
the right side of the boiler or the top of the
boiler for cleaning flueways.
5. For minimum clearances to combustible
materials. See Figure 2.
C. PROVIDE COMBUSTION AND VENTILATION
AIR. Local and National Codes may apply and
should be referenced.
NOTES:
1. Listed clearances comply with American
National Standard ANSI/NFPA 31, Installation
of Oil Burning Equipment.
2. V8H Series boilers can be installed in rooms
with clearances from combustible material
as listed above. Listed clearances cannot be
reduced for alcove or closet installations.
3. For reduced clearances to combustible
material, protection must be provided as
described in the above ANSI/NFPA 31
standard.
2Pre-Installation

9
110218-01 - 3/20
V8H Installation & Service Manual
1. Determine volume of space (boiler room).
Rooms communicating directly with the
space in which the appliances are installed,
through openings not furnished with doors, are
considered a part of the space.
Volume(ft3) = Length(ft) x Width(ft) x Height(ft)
2. Determine total input of all appliances in the
space.
Add inputs of all appliances in the space and
round the result to the nearest 1000 BTU per
hour.
3. Determine type of space. Divide Volume by
total input of all appliances in space. If the
result is greater than or equal to 50 ft3/1000
BTU per hour, then it is considered an
unconfined space. If the result is less than
50 ft3/1000 BTU per hour then the space is
considered a confined space.
4. For boiler located in an unconfined space of a
conventionally constructed building, the fresh
air infiltration through cracks around windows
and doors normally provides adequate air for
combustion and ventilation.
5. For boiler located in a confined space or an
unconfined space in a building of unusually
tight construction, provide outdoor air.
a. Outdoor air for combustion may be
provided with an optional U.S. Boiler
Company V8H™ Fresh Air Accessory
Kit (ONLY AVAILABLE ON BECKETT
BURNERS WITH PLASTIC COVER
APPLICATION, P/N 102119-01). Refer
to Fresh Air Accessory Kit Instructions for
installation and air intake piping details.
or
b. Outdoor air may be provided with the
use of two permanent openings which
communicate directly or by duct with the
outdoors or spaces (crawl or attic) freely
communicating with the outdoors. Locate
one opening within 12 inches of top of
space. Locate remaining opening within
12 inches of bottom of space. Minimum
dimension of air opening is 3 inches. Size
each opening per following:
i. Direct communication with outdoors.
Minimum free area of 1 square inch
per 4,000 BTU per hour input of all
equipment in space.
ii. Vertical ducts. Minimum free area of
1 square inch per 4,000 BTU per hour
input of all equipment in space. Duct
cross-sectional area shall be same as
opening free area.
iii. Horizontal ducts. Minimum free area of
1 square inch per 2,000 BTU per hour
input of all equipment in space. Duct
cross-sectional area shall be same as
opening free area.
Alternate method for boiler located
within confined space.Use indoor air if
two permanent openings communicate
directly with additional space(s) of
sufficient volume such that combined
volume of all spaces meet criteria for
unconfined space. Size each opening
for minimum free area of 1 square inch
per 1,000 BTU per hour input of all
equipment in spaces, but not less than
100 square inches.
6. Louvers and Grilles of Ventilation Ducts
a. All outside openings should be screened
and louvered. Screens used should not be
smaller than 1/4 inch mesh. Louvers will
prevent the entrance of rain and snow.
b. Free area requirements need to consider
the blocking effect of louvers, grilles, or
screens protecting the openings. If the free
area of the louver or grille is not known,
assume wood louvers have 20-25 percent
free area and metal louvers and grilles have
60-75 percent free area.
c. Louvers and grilles must be fixed in the
open position, or interlocked with the
equipment to open automatically during
equipment operation.
NOTICE Clearance to venting is for single wall
vent pipe. If Type L vent is used, clearance may
be reduced to the minimum required by the vent
pipe manufacturer.
2Pre-Installation (continued)
WARNING
Adequate combustion and ventilation air must
be provided to assure proper combustion and
to maintain safe ambient air temperatures.
DO NOT install boiler where gasoline or other
flammable vapors or liquids, or sources of
hydrocarbons (i.e. bleaches, fabric softeners,
etc.) are used or stored.
!

10 110218-01 - 3/20
V8H Installation & Service Manual
A. REMOVAL OF BARE BOILER FROM SKID
1. Boiler is secured to skid with 4 bolts, 2 in front
and 2 in rear of shipping skid, see Figure 3.
Remove all bolts.
Figure 3: Knockdown Boiler Removal from Skid
2. Tilt boiler to right and to rear. Using right rear
leg as pivot, rotate boiler 90° in a clockwise
direction, and lower left side of boiler to floor.
Tilt boiler and remove skid.
B. MOVE BOILER TO PERMANENT POSITION
by sliding or walking.
C. TEST BOILER FOR LEAKS before installing
controls, trim, and jacket, and before connecting
to heating system.
1. Loosen nuts on tie rods until only finger tight.
2. Install pressure gauge (at least 50 PSI
capacity), a hose to the city water and a valve
in the supply tapping. Plug remainder of
tappings.
3. Fill boiler with water and apply a pressure of
at least 10 PSI but no more than 50 PSI gauge
pressure.
WARNING
Assure that there is not air left inside boiler when
checking for leaks. DO NOT test for leaks with
pressurized air.
4. Examine boiler carefully inside and outside for
leaks or damage due to shipment or handling.
D. DRAIN WATER FROM BOILER. Remove
gauge, valve and plugs from those tappings to be
used. Leave other tappings plugged or bushed
according to Figure 5.
E. INSPECT JOINTS BETWEEN SECTIONS. All
joints are factory sealed. If there are any spaces
due to shipment or handling, seal them with boiler
putty.
F. INSPECT FLUE COVER PLATES for tightness.
If loose, retighten mounting hardware. If flue plate
or sealing rope is damaged, repair or replace as
needed.
Figure 4: Boiler Canopy Installation
G. INSTALL FLUE BAFFLES
1. Insert one (1) Flue Baffle into each flue way.
H. INSTALL AND SECURE CANOPY with gasket
and hardware provided to ensure gas tight seal —
see Figure 4.
1. Cut two (2) strips 13 ¾” long from the roll of
gasket insulation. Place one (1) strip across the
top of the front section and the other across the
rear section as shown in Figure 4.
2. Cut the remainder of the roll into two (2) equal
pieces. Place each piece along the sides,
allowing the ends to overlap the front and rear
pieces.
CAUTION
DO NOT allow any flueway blockage by gasket.
3. Position canopy body within the retaining bar
which borders the flueway openings on top of
the bare boiler block assembly.
NOTICE Jacket support bracket must be facing
left side of boiler - see Figure 4. Jacket will not fit
if bracket is not oriented correctly.
4. Secure canopy to boiler with two (2) 1/4" - 20 x
3" long carriage bolts, 1/4" flat washers and 1/4"
- 20 wing nuts provided.
3Knock Down Boiler Assembly
!
!

11
110218-01 - 3/20
V8H Installation & Service Manual
Figure 5: Boiler Tapping Locations and Usage (Knockdown Boilers Only)
PURPOSE OF TAPPINGS
Tapping
Location
Size
NPT
Water Boiler
Non-Heater Front Heater
A ¾" Boiler Control Boiler Control
B ¼" Temperature/Pressure Gauge
C ¾" N/A
C-C ¾" N/A
D ½" N/A
G 1½" Return
H 1½" Plugged
J 1½" Flush Plug
K 2" Front Supply
L 2" Plugged
M ¾" Relief Valve
P ¾" Aux. Tapping -
Plugged N/A
R ¾" Auxiliary Tapping - Plugged
S ½" N/A
T 1" N/A
*In lieu of Tankless Heater
3Knock Down Boiler Assembly (continued)

12 110218-01 - 3/20
V8H Installation & Service Manual
Figure 6: Knockdown Boiler Jacket Assembly
I. INSTALL TRIM. The following water trim will be
concealed or inaccessible after boiler jacket is
installed, see Figure 5 for boiler tapping locations
and usage.
1. WATER BOILER — Top tappings:
a. Tapping “L” — Install 2” NPT plug in rear
section top supply tapping — all boiler
sizes.
b. Tapping “M” —Install ¾” NPT x 8” long
nipple into ¾” NPT tapping located next to
front section top supply tapping — all boiler
sizes.
J. INSTALL COMBUSTION CHAMBER RING/
PLATE
1. Remove burner swing door and hinge
assembly. Remove one (1) 5/16"-18 flange nut
and washer from right side latching stud and
one (1) 5/16"- 18 x 3½" cap screw on left side
used for securing burner swing door to the
boiler section. Swing door open and remove
5/16" hairpin cotter from rear hinge pin (see
Figure 7). While holding swing door remove
hinge pin and set door aside. Remove two (2)
5/16"-18 x ¾" long cap screws securing the
hinge bracket to the boiler section.
2. The V8H3WE utilizes a combustion chamber
ring. To install, place the combustion chamber
ring in the center of the front section.
3. The V8H5WE utilizes a combustion chamber
plate. To install, place the combustion chamber
plate in the center of the front section.
K. INSTALL BOILER JACKET. (See Figure 6).
1. Install jacket rear panel support bracket. (See
Figure 6, Item 2A). Align bracket with two
(2) 5/16"-18 tapped holes in rear section and
secure with two (2) 5/16"-18 x 1/2" long cap
screws.
2. Install jacket rear panel. (See Figure 6, Item
2B). Align holes in jacket rear panel and
support bracket. Secure with two (2) #8 x 1/2"
long sheet metal screws.
3. Jacket Front Panel
a. Install black plastic collar extension to
jacket front panels for 7-13/16" diameter
tankless heater opening. (See Figure 6,
Items 2C and 2D). Engage two (2) of the
collar retaining tabs over raw edge of jacket
opening. Provide support behind the panel
with one hand while applying pressure
on collar to snap each tab over edge of
opening until all eight (8) tabs are securing
collar.
b. Install jacket front panel. Locate two (2)
11/32" diameter holes, one round, one
obround, on front panel approximately 16”
up from the bottom of the panel. Align
these holes with the similarly located 5/16"-
18 tappings on the front section. Secure
with two (2) 5/16"-18 x 1/2" long cap screws.
3Knock Down Boiler Assembly (continued)

13
110218-01 - 3/20
V8H Installation & Service Manual
4. Install jacket left side panel. (See Figure 6,
Item 2E). Fold panel at perforation keeping
insulation inward. Align left side panel
mounting holes with the front and rear panel
holes. Secure with #8 x ½” long sheet metal
screws.
5. Install jacket top panel. (See Figure 6, Item
2F). Place jacket top panel on boiler and
secure to front, rear and left side panels with
#8 x ½” long sheet metal screws.
6. Install jacket right side access panel. (See
Figure 6, Item 2G). Align right side panel
mounting holes with front and rear panel holes.
Secure with #8 x ½” long sheet metal screws.
7. Attach the labels shipped in the instruction
envelope as follows:
a. Locate both the Rating Label and
Combination Warning Label (P/N 102801-
03). Remove paper backing from the
labels and apply to the jacket top panel in
approximate locations shown in (Figure 6,
Item 2F).
L. INSTALL BURNER.
(See Figure 7).
1. Check target wall and combustion chamber
blanket. If any damage or movement occurred
during shipment, replace as needed.
2. Locate burner swing door and hinge assembly
removed in Paragraph J, No. 1. Check the
burner swing door insulation and rope gasket
for damage and adhesion. If damaged,
replace insulation or gasket. If insulation or
gasket is loose, reattach to swing door with
RTV 732 or 736 silicone caulk.
3. Install burner swing door in reverse order from
Paragraph J, No. 1.
4. Use the following procedure to properly close
and secure the burner swing door after it
has been removed and re-installed for Field
Assembly (Knockdown Boiler) or opened for
inspection, cleaning or field service (refer to
Figures 12A and 12B):
Step 1.Lift the door up unto the built-in cast
ramp/door rest (protruding from the bottom
of the front section casting - see Figure
12A), while rotating the articulated hinge
and door to the right and engaging the slot
(on right side of door) unto the 5/16" stud
protruding from the front section.
Step 2. Use one hand to help hold door in
position by applying pressure directly to
the door while re-installing the securing
hardware with your opposite hand. Always
install right side latching hardware (5/16"
flange nut and flat washer) first, then
install left side hinge hardware (5/16" x
3-1/2" lg. hex head flange bolt) second.
Apply additional pressure while hand
tightening the hardware as far as possible,
then release the pressure.
Figure 7: Oil Burner Installation (Beckett Burner Shown)
3Knock Down Boiler Assembly (continued)

14 110218-01 - 3/20
V8H Installation & Service Manual
NOTICE When securing burner swing door make
sure door is drawn-in equally on both sides.
Step 3. Use a hand wrench to tighten door
hardware and always start with the right
side flange nut first (see Figure 12B). Use an
alternating tightening method from right side
flange nut to left side flange bolt to tighten door
equally until sealed without applying excessive
torque. Never tighten left side flange bolt first or
tighten either piece of hardware 100% without
using the alternating tightening method described
above.
Failure to follow the prescribed procedure
could cause thread damage to casting or a
leak in the door seal. If left side flange bolt
is tightened before right side flange nut,
right side of door can not be drawn-in to
provide an air tight seal, as shown in Figure
12C. Applying excessive torque will only
cause thread damage.
5. Place oil burner gasket on burner and align
holes.
CAUTION
DO NOT install burner without gasket.
6. Back out (4) 5/16”-18 x 3/4” long cap screws
factory installed into burner swing door
about 1/4". Insert oil burner into the opening
of the burner door, rotate slightly clockwise
to align burner mounting flange teardrop
cutouts with cap screw hex heads and
engage all four cap screws simultaneously.
Then, rotate the burner slightly
counterclockwise, level it and fully tighten all
four cap screws.
7. Inspect electrodes, head setting and factory
installed oil nozzle. Refer to the instructions
provided with the burner and Table 12.
M. INSTALL TRIM AND CONTROLS (See Figures
1A, 1B, and 5).
1. Thread combination pressure/temperature
gauge into ¼” NPT tapping. Tighten with
wrench applied to the square shank of the
gauge.
CAUTION
DO NOT apply pressure to the gauge case - this
may result in inaccurate readings.
2. Lower front section tapping “G” is used for
standard return on water boilers, see Figure
5. If circulator (supplied with boiler) is to be
mounted in return piping connected
directly to 1½" NPT boiler return tapping "G",
use the piping arrangements outlined in steps
a. thru e. as follows: (see Figures 15A and
15B).
a. Thread 1½” NPT x 3” long nipple and 1½”
NPT x 90° elbow with ¾" NPT side outlet into
the return tapping and tighten with a pipe
wrench.
b. Screw drain valve into ¾" NPT side outlet of
the 1½” NPT x 90° elbow.
c. Thread 1½” NPT x 18” long nipple (supplied
by others) into the 1½" NPT x 90° elbow and
tighten with a pipe wrench.
d. Thread one of the circulator flange onto
the nipple and tighten with a pipe wrench.
Position flange so that the bolt slots are
parallel to the boiler front.
e. Place a circular flange gasket in the flange
groove on the circulator and mount the
circulator on the flange. Note that this is
the return piping and the flow arrow on
the circulator should point down . Fasten
circulator with 7/16” - 14 x 1½" long cap
screws and 7/16" - 14 nuts.
f. Fasten the second circulator flange and
gasket to the circulator.
g. Remove supplied circulator harness from
Part Bag. Remove circulator junction box
cover and knockout in circulator junction
box flange. Insert harness end with two
wires having bare-stripped ends through
knockout hole and push-in to engage
harness connector into flange. Connect
harness conductors to circulator junction
box wires as follows - White to White and
Blue to Yellow (or, Blue) and secure with
wire nuts (installer provided).
3. Install relief valve, as shown in Figure 1A and
1B onto ¾” NPT x 8” nipple previously installed
in Paragraph I, No. 2, step b. Tighten with
wrench. Pipe discharge as shown in Figures
14A and 14B. Installation of the relief valve
must be consistent with ANSI/ASME Boiler and
Pressure Vessel Code, Section IV.
WARNING
Safety valve discharge piping must be piped
near floor to eliminate potential of severe burns.
DO NOT pipe in any area where freezing could
occur. DO NOT install any shut-off valves,
plugs or caps.
4. On boilers without a heater opening, install the
well into the 3/4” NPT tapping “A” located on
the front of the boiler in the upper left corner.
3Knock Down Boiler Assembly (continued)
!
!
!

15
110218-01 - 3/20
V8H Installation & Service Manual
See Figures 1A and 5. Tighten the well and
fully insert limit sensor into immersion well
such that the tip on the limit sensor touches the
bottom of the immersion well. See Figure 8.
Secure control to immersion well with setscrew.
WARNING
Aquastat bulb must be fully inserted into the
well.
5. On boilers with a heater opening, install the
well in either the 1/2” NPT or 3/4” NPT
tapping on the tankless heater plate or cover
plate. See Figures 1B, and 5. Tighten the
well and fully insert limit sensor into immersion
well such that the tip on the limit sensor probe
touches the bottom of the immersion well.
See Figure 8. Secure control to immersion
well with setscrew.
6. After control is installed and secured, remove
control cover. Then, remove knockout located
directly above factory connected limit harness
on right side flange of control. Insert circulator
harness end with attached fork terminals thru
knockout hole and push-in to engage harness
connector into flange. Connect wires to control
terminals as follows - Blue to C1 and White
to C2 and tighten securely. Re-install control
cover.
!
3Knock Down Boiler Assembly (continued)
Figure 9: Limit Sensor Insertion
7. Connect Field Wiring.
a. Water boilers without tankless heater.
Connect the field wiring to the aquastat
control. Make the wiring connections as
shown on Figure 20A or 20C.
b. Water boilers with front heater. Connect the
field wiring to the aquastat control. Make
the wiring connections as shown on Figure
20B or 20C.
c. Refer to Paragraph N for details on use of
burner disconnect junction box provided
with all knockdown boiler builds.
N. BURNERS SUPPLIED BY U.S. BOILER
COMPANY utilize a burner disconnect harness
that is pre-wired into the burner junction box and
primary control. Packed in the canopy carton is
the mating burner disconnect junction assembly
and mounting hardware for use with these
burners.
If you are using a burner with the disconnect
harness, complete the following assembly
instructions for mounting the mating burner
disconnect junction box, see Figure 10.

16 110218-01 - 3/20
V8H Installation & Service Manual
Figure 10: Burner Disconnect Junction Box with Power Outlet Receptacle
(Mated to Burners with Disconnect Harness)
3Knock Down Boiler Assembly (continued)

17
110218-01 - 3/20
V8H Installation & Service Manual
A. REMOVE CRATE.
1. Remove all fasteners at crate skid.
2. Lift outside container and remove all other
inside protective spacers and bracing.
Remove draft regulator box and miscellaneous
trim bag containing safety or relief valve, and
pipe fittings.
B. REMOVE BOILER FROM SKID.
1. Boiler is secured to base with 4 bolts, 2 in front
and 2 in rear of shipping skid, see Figure 11.
Remove all bolts.
2. Tilt boiler to right and to rear. Using right rear
leg as pivot, rotate boiler 90° in a clockwise
direction, and lower left side of boiler to floor.
Tilt boiler and remove crate skid. Care should
be exercised to prevent damage to jacket or
burner.
Figure 11 : Packaged Boiler Removal from Skid
C. MOVE BOILER TO PERMANENT POSITION
by sliding or walking.
D. PROCEDURE TO OPEN, CLOSE AND SECURE
BURNER SWING DOOR with articulated hinge.
Throughout this manual you will be instructed to
open and close the burner swing door for various
reasons. There is a proper and improper method
to closing and securing the burner swing door
after it has been removed and re-installed for
Field Assembly (Knockdown Boiler) or opened for
inspection, cleaning or field service.
1. TO OPEN BURNER SWING DOOR (see
Figures 12A and 12B).
Step 1. Loosen and remove right side latching
hardware (5/16" flange nut and washer).
Step 2. Loosen and remove left side hinge
hardware (5/16" x 3-1/2" lg. hex head flange
bolt).
Step 3. The duel pivot articulated hinge allows
right side of door to be pulled outward and
rotated to the left all in one motion. To do
so, place your right hand under burner air
tube and lift up slightly to help carry the
weight of the door and burner. Use your
left hand to grasp the door's left side hinge
flange, pull outward to rotate the hinge, this
motion will move the door outward and to
the left approximately 3" (see Figure 12B,
Position 2).
Step 4. From this position the door can
be swung clear of the vertical circulator
return piping to provide full access to the
combustion chamber and burner head (see
Figure 12B, Position 3).
2. Perform routine inspection, service or cleaning
as necessary.
3. To close Burner Swing Door (see Figures 12A
and 12B):
Step 1. From the fully open position, rotate
Burner Swing Door toward the closed
position. Make sure that the articulated
hinge is rotated to the extreme left position
to allow the door to clear the vertical
circulator return piping as shown in Figure
12B, Position 2.
Step 2. Grasp the door's left side hinge flange
in your left hand and place your right hand
under the burner air tube to lift upward. Lift
the door up unto the built-in cast ramp/door
rest (protruding from the bottom of the front
section casting - see Figure 12A), while
rotating the articulated hinge and door to
the right and engaging the slot (on right
side of door) unto the 5/16" stud protruding
from the front section.
Step 3. Use one hand to help hold door in
position by lifting up on rear burner housing
or applying pressure directly to the door
while re-installing the securing hardware
with your opposite hand. Always install
right side latching hardware (5/16" flange
nut and flat washer) first, then install left
side hinge hardware (5/16" x 3-1/2" lg.
hex head flange bolt) second. Apply
additional pressure while hand tightening
the hardware as far as possible, then
release the pressure.
4Packaged Boiler Assembly
CAUTION
DO NOT drop boiler. DO NOT bump boiler
jacket against floor.
!

18 110218-01 - 3/20
V8H Installation & Service Manual
NOTICE When securing burner swing door make
sure door is drawn-in equally on both sides.
Step 4. Use a hand wrench to tighten
door hardware and always start with
the right side flange nut first. Use an
alternating tightening method from right
side flange nut to left side flange bolt to
tighten door equally until sealed without
applying excessive torque. Never tighten
left side flange bolt first or tighten either
piece of hardware 100% without using the
alternating tightening method described
above.
Failure to follow the prescribed procedure
could cause thread damage to casting or
a leak in the door seal. If left side flange
bolt is tightened before right side flange
nut, right side of door can not be drawn-in
to provide an air tight seal, as shown in
Figure 12C. Applying excessive torque will
only cause thread damage.
E. INSPECT COMBUSTION CHAMBER TARGET
WALL, AND SWING DOOR GASKET.
1. Open burner swing door using procedure
previously outlined in Paragraph D of this
section.
2. Using a flashlight, inspect the rear target wall.
The target wall should be rigidly secured to the
rear boiler section.
3. Inspect ceramic rope located on the swing
door. The rope must be evenly distributed
around the perimeter of the door groove and
cannot bunch or overhang. There must not
be a gap where the two ends of the rope meet.
Repair or replace if the rope is damaged or if
there is a gap between the ends.
Figure 12A: Partial Front View - Burner Swing Door Mounted to Boiler - Fully Closed and Secured
4Packaged Boiler Assembly (continued)
F. INSTALL COMBUSTION CHAMBER RING/
PLATE.
Refer to Section 3, Paragraph J for installation
instructions.
G. INSTALL OIL BURNER. Refer to Section III,
Paragraph L for burner installation instructions.
H. INSTALL SAFETY OR RELIEF VALVE IN
TAPPING "M", see Figure 5.
Use ¾" NPT x 8" nipple and/or ¾" NPT coupling
included in trim bag. Safety or Relief Valve must
be installed with spindle in vertical position.
Pipe discharge as shown in Figures 14 and 15.
Installation of the safety or relief valve must be
consistent with ANSI/ASME Boiler and Pressure
Vessel Code, Section IV.
WARNING
Safety valve discharge piping must be piped
near floor to eliminate potential of severe burns.
DO NOT pipe in any area where freezing could
occur. DO NOT install any shut-off valves,
plugs or caps.
I. PACKAGED WATER BOILERS WITH
CIRCULATORS. If your boiler build comes with
factory supplied circulator and circulator is to
be mounted in return piping connected directly
to 1½" boiler return tapping "G", use piping
and wiring arrangements outlined in Section III:
Knockdown Boiler Assembly, Paragraph P, Step 2.
!

19
110218-01 - 3/20
V8H Installation & Service Manual
Figure 12B: Top View - Burner Swing Door Mounted to Cast Iron Block Assembly (Jacket Removed for Clarity)
4Packaged Boiler Assembly (continued)

20 110218-01 - 3/20
V8H Installation & Service Manual
Figure 12C: Top View - Burner Swing Door Fully Closed but Not Properly Secured or Sealed
4Packaged Boiler Assembly (continued)