Viessmann Vitoflex 300-UF 390 Installation and user guide

Service and
Maintenance Instructions
for use by engineers and heating contractors
5603 884 - 04 03/2017
Read and save these instructions
for future reference.
Vitoflex 300-UF 390, 530, 720, 950 AND 1250
Wood-fired Boiler
Output range: UF 390, 334 to 1331 kW
UF 530, 450 to 1808 kW
UF 720, 614 to 2457 kW
UF 950, 812 to 3242 kW
UF 1250, 1065 to 4265 kW
Vitoflex 300-UF
Product may not be exactly as shown
If the information in this manual is not
followed exactly, a fire or explosion
may result causing property damage,
personal injury or loss of life.
Improper installation, adjustment and/or
operation could cause carbon monoxide
poisoning resulting in injury or loss of life.
This product must be installed and serviced
by a professional service technician who is
experienced and qualified in hot water boiler
installation and wood fuel combustion.
Do not store or use gasoline or other
flammable fluids in the vicinity of this or
any other appliance.
WHAT TO DO IF YOU SMELL FLUE GAS
Deactivate heating equipment
Open windows and doors.
Inform your heating contractor
Please file in Service Binder
WARNING
WARNING
IMPORTANT
H

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Safety, Installation and Warranty Requirements
WARNING
Installers must follow local regulations with respect to
installation of carbon monoxide detectors. Follow the
manufacturer’s maintenance schedule of the boiler
contained in the section “Cleaning and Maintenance”.
Please ensure that these instructions are read and understood before commencing service and/or maintenance. Failure
to comply with the instructions listed below and details printed in this manual can cause product/property damage,
severe personal injury and/or loss of life. Ensure all requirements below are understood and fulfilled (including detailed
information found in manual subsections).
Product documentation
Read all applicable documentation before commencing
installation. Store documentation near boiler in a
readily accessible location for reference in the future
by service personnel.
For a listing of applicable literature,
please see section entitled “Important
Regulatory and Safety Requirements”.
Warranty
Information contained in this and
related product documentation must
be read and followed. Failure to do
so renders the warranty null and void.
Licensed professional heating contractor
The installation, adjustment, service and maintenance
of this equipment must be performed by a licensed
professional heating contractor.
Please see section entitled
“Important Regulatory and Installation
Requirements”.
Contaminated air
Air contaminated by chemicals can cause by-products
in the combustion process, which are poisonous to
inhabitants and destructive to Viessmann equipment.
For a listing of chemicals which
cannot be stored in or near the
boiler room, please see subsection
entitled “Mechanical Room”.
Advice to owner
Once the installation work is complete, the heating
contractor must familiarize the system operator/
ultimate owner with all equipment, as well as safety
precautions/requirements, shutdown procedure, and
the need for professional service.
Carbon monoxide
Improper installation, adjustment, service and/or
maintenance can cause flue products to flow into
living space. Flue products contain poisonous carbon
monoxide gas.
For information pertaining to the proper
installation, adjustment, service and
maintenance of this equipment to avoid
formation of carbon monoxide, refer to
the “Installation and Operating Instructions”.
Fresh air
This equipment requires fresh air for
safe operation and must be installed
ensuring provisions for adequate
combustion and ventilation air exist.
For information pertaining to the
fresh air requirements of this product,
please see subsection entitled
“Combustion Air Supply”.
Equipment venting
Never operate the boiler without an installed venting
system. An improper venting system can cause
carbon monoxide poisoning.
For information pertaining to venting
and chimney requirements, refer to the
“Installation and Operating Instructions”.
All products of combustion must be
safely vented to the outdoors.
Introduction

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Vitoflex 300-UF Service & Maintenance Introduction
About these Instructions
Take note of all symbols and notations intended to draw attention to potential hazards or important
product information. These include ”WARNING”, ”CAUTION”, and ”IMPORTANT”. See below.
CAUTION
Cautions draw your attention to the presence of potential
hazards or important product information.
WARNING
Warnings draw your attention to the presence of potential
hazards or important product information.

IMPORTANT
Indicates an imminently hazardous situation which,
if not avoided, could result in death, serious injury or
substantial product/property damage.
Indicates an imminently hazardous situation which,
if not avoided, may result in minor injury or product/
property damage.
Helpful hints for installation, operation or maintenance
which pertain to the product.
This symbol indicates to note additional information.
This symbol indicates that other instructions must be
referenced.
Note: Viessmann Manufacturing Company Inc. reserves
the right to make product changes or updates
without notice and will not be held liable for
errors or omissions in the product literature.

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Table of Contents
Introduction
General Information
Safety
Maintenance
Troubleshooting Guide
Page
Safety, Installation and Warranty Requirements..............2
About these Instructions..............................................3
Product Information.....................................................5
Important Regulatory and Installation Requirements ........6
Safety Instructions......................................................8
Carbon Monoxide........................................................9
Extreme Weather Conditions......................................10
Hazardous Material....................................................11
Mechanical Room.....................................................12
Combustion Air Supply..............................................13
Components of the Biomass Boiler..............................14
Cleaning..................................................................15
Boiler.................................................................15
Heat exchanger tube displacement rods.................16
Installing the displacement rods.............................16
Removing the displacement rods...........................16
Flue gas cyclone (optional)....................................17
Pneumatic cleaning system (optional)...................17
Flue gas re-circulation system (optional) ...............18
Feed Systems...........................................................19
Shutdown...............................................................20
Boiler.................................................................20
Extraction and conveyance systems.......................20
Control system....................................................20
Replacing the backup battery................................20
Ash disposal.......................................................20
Disposal of the boiler............................................20
Instructions regarding removal...............................20
Waste disposal....................................................20
System Faults...........................................................21

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Maximum allowable working pressure (water)…30 or 60 psi
Maximum water temperature…250°F (120°C) (closed loop)
Maximum boiler temperature……210°F (99°C) (open loop)
This boiler does not require a flow switch.
Codes
CSA B366.1-M91
Solid Fuel Fired Central Heating Appliances
CSA C22.2 NO. 3-M1988 (latest edition)
Electrical Features of Fuel Burning Equipment
UL2523
Solid Fuel-Fired Hydronic Heating Appliances, Water
Heaters and Boilers
CSA B365-10
Installation Code for Solid Fuel Burning Appliances
and Equipment
ASME section IV boilers and pressure vessels.
Viessmann solid-fuel boiler can only be installed and
serviced by qualified trained personnel.
Steel wood-fired hot water heating boiler.
For operation primarily with modulating boiler water
temperatures in closed loop forced circulation hot water
heating systems. Under certain conditions, open loop
systems may also be considered. Contact Viessmann
for details.
WARNING
Exposing the boiler to pressures and temperatures in
excess of those listed will result in damages and will
render the warranty null and void.
Product Information
General Information

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Important Regulatory and Installation Requirements
Working on the equipment
The installation, adjustment, service, and maintenance
of this boiler must be done by a licensed professional
heating contractor who is qualified and experienced in the
installation, service and maintenance of hot water boilers.
Ensure main power supply to equipment, the heating
system, and all external controls have been deactivated.
Take precautions to avoid accidental activation of power
during service work.
Technical literature
Literature applicable to all aspects of the Vitoflex 300-UF
wood-fired boiler:
- Installation and Operating Instructions
- Service and Maintenance Instructions
- Field Wiring Diagram
The completeness and functionality of field supplied
electrical controls and components must be verified
by the heating contractor. These include low-water
cutoffs, flow switches (if used), staging controls,
pumps, motorized valves, air vents, thermostats, etc.
Leave all literature at the installation site and advise
the system operator/ultimate owner where the
literature can be found. Contact Viessmann for
additional copies.
This product comes with several safety instruction
labels attached.
Do not remove!
Contact Viessmann immediately if replacement labels
are required.
Please carefully read this manual prior to attempting
service and maintenance. Any warranty is null and void
if these instructions are not followed.
For information regarding other Viessmann System
Technology componentry, please reference documentation
of the respective product.
We offer frequent installation and service seminars to
familiarize our partners with our products. Please inquire.
General Information
RISK OF INJURY: Shut the system off before starting
any cleaning. Be absolutely sure to wear protective
gloves, protective eyewear if required and use the
cleaning tools that come with the system (danger of
blow-ups, burns and getting crushed)!
CAUTION

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Vitoflex 300-UF Service & Maintenance General Information
WARNING
The boiler must not be located in areas or rooms where
chemicals are stored, or aggressive vapors from (i.e.
bleach, hair spray, methyl chloride, carbon tetrachloride
or perchloroethylene) or high dust levels or humidity
levels are present. Heat exchanger corrosion might
occur and reduce the lifetime of the boiler significantly.
If above criteria are not properly observed and boiler
damage results, any warranty on the complete boiler
and related components will be null and void.
Important Regulatory and Installation Requirements (continued)
Regular maintenance and service
The entire heating system must be cleaned and serviced
on a regular basis by a qualified contractor or service
agency to ensure reliable, energy-efficient, and
environmentally friendly operation.
The build-up of soot on the heat exchanger raises the
flue gas temperature and reduces efficiency.
IMPORTANT
Keep boiler and boiler room clear and free of combustible
materials, gasoline and other flammable vapors and
liquids. Do not obstruct the flow of combustion and
ventilation air. All inspection, maintenance and service
must be performed by a qualified heating contractor.
WARNING
Improper installation, adjustment, service, or maintenance
can cause flue products to flow into living space. Flue
products contain poisonous carbon monoxide gas, which
can cause nausea or asphyxiation resulting in severe
personal injury or loss of life.
Important to know
Do not use this boiler if any part has been under, or
exposed to, water. Immediately call a qualified heating
contractor to inspect the boiler and to replace any part
of the control system, which has been under or exposed
to water.
WARNING
Service and maintenance can only be performed by a
qualified heating contractor.

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IMPORTANT
The local building codes and regulations must be followed
by the heating contractor.
IMPORTANT
Please refer to the Installation and Operating
Instructions for installation, commissioning
and technical specification information. The
Installation and Operating Instructions contain
the necessary safety and national/local code
requirements which, if not followed exactly,
may lead to property damage, personal injuries
and/or death.
Important Information
Safety instructions
When carrying out work on the heating system, such as
cleaning and maintenance, wear appropriate protective
equipment when required.
There is a danger of getting injured through: burning,
knocking against corners and edges, crushing in moving
parts and noise.
Power supply: 120V or 240V/1/ and 208V/3/ 60Hz
In case of an emergency, the Vitoflex 300-UF can be
disconnected from the electrical power supply at all the
leads by the main switch on the control cabinet.
CAUTION
FIRE HAZARD:
The boiler must NEVER be operated with the doors open!
Any burning bits that escape could start a fire.
RISK OF INJURY:
If the doors are open during operation, sparks or flames
could leap out.
Equipment for dissipating excess heat: a competent
specialist should examine the operational reliability of
the thermal safety flush valve annually. The safety
heat exchanger must not by any means be used as an
operational heat exchanger.
Seals: for the functioning and controllability of the boiler,
it is important that no unwanted air can enter unchecked
through leaks.
The doors and lids have to shut tight - any damaged
seals must be replaced immediately. Tighten the retaining
screws and handles well.
Operation, cleaning and maintenance: bear in mind that
even the best product can only fulfill its functions well,
doing so for a long time and free of malfunctions, if
operated and maintained properly.
Compliance with the “Cleaning” section is mandatory!
Safety Instructions
IMPORTANT
Doors: for safety keep firing and ashpit doors tightly closed
Safety
If you notice fire coming from the appliance, call the fire
department immediately!
DO NOT attempt to extinguish the fire unless qualified to
do so.
WARNING
Fire causes a risk of burns and explosion!
Shut down the boiler
Close fuel shut-off valves
Use a tested fire extinguisher, class ABC.

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Carbon monoxide
The U.S. Consumer Product Safety Commission strongly
recommends the installation of carbon monoxide detectors
in buildings in which gas-burning equipment is installed.
Carbon monoxide (CO) is a colorless, odorless gas, which
may be produced during incomplete combustion of fuel
and/or when the flame does not receive an adequate
supply of combustion air. Carbon monoxide can cause
severe personal injury or loss of life.
Therefore, carbon monoxide detectors that are in
compliance with a nationally recognized standard
(e.g. ANSI/UL 2034-2002, CSA 6.19-01) should be
installed and maintained in buildings that contain
gas-burning equipment.
Note: Viessmann does not test any detectors and makes
no representation regarding any brand or type of
detector.
For safe operation
We recommend that you frequently:
- Check for debris which could obstruct the flow of
flue gases. The vent or chimney must not be blocked.
A blocked or partially blocked vent or chimney can
cause flue gases to leak into the structure. Flue gases
leaking into the house can cause injury or death.
Blocked or partially blocked chimneys must have the
blockage removed by a qualified heating contractor.
- Check pressure gage for correct system (water)
pressure. Check for water on the floor from the
discharge pipe of the pressure relief valve or any
other pipe, pipe joint, valve or air vent.
- Check for moisture, water, or appearance of rust
on the flue gas pipes, their joints as well as vent
dampers, or side wall vent terminals (if so equipped).
- Ensure that nothing is obstructing the flow of
combustion and ventilation air and no chemicals,
garbage, gasoline, combustible materials, flammable
vapors and liquids are stored (not even temporarily)
in the vicinity of the boiler.
- DO NOT allow unsupervised children near the boiler.
Service/inspection of the boiler and the system must be
performed on a regular basis. Maintenance, service and
cleaning are specified in the section on maintenance.
Before the heating season begins, it is recommended that
the boiler be serviced by a qualified heating technician.
WARNING
Improper installation, adjustment, service, or maintenance
can cause flue products to flow into living space. Flue
products contain poisonous carbon monoxide gas, which
can cause nausea or asphyxiation resulting in severe
personal injury or loss of life.
WARNING
The operator/ultimate owner is required to have the heat-
ing boiler and controls checked, as a minimum once per
year, by the original installer or by a competent heating
contractor familiar with the equipment. Defects must be
corrected immediately.
Carbon Monoxide
Safety

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Extreme Weather Conditions
Safety
WARNING
As there are no user-serviceable parts on the boiler,
or control, the end-user must not perform service
activities of any kind on system components. Failure
to heed this warning can cause property damage,
severe personal injury or loss of life.
Frozen water pipe hazard
Your heating boiler is designed to provide a warm and
comfortable living environment. It is NOT designed to
ensure against freezing of water pipes. The boiler is
equipped with several safety devices that are designed
to shut down the boiler and to prevent it from restarting
in the event of various unsafe conditions.
If your boiler remains off for an extended period of time
during cold weather, water pipes may freeze and burst,
resulting in extensive water damage and conditions in
which mold could grow. Certain molds are known to
cause respiratory problems, as well as to pose other
serious health risks. In case of water damage, immediate
measures should be taken to dry out affected areas as
quickly as possible to prevent mold from developing.
If your home will be unattended for an extended period
of time during cold weather, you should...
Shut off the water supply to the building, drain the water
pipes and add antifreeze for potable water to drain traps
and toilet tanks. Open faucets where appropriate.
or…
Have someone check the building frequently during cold
weather and call a qualified service agency if required.
or...
Install a reliable remote temperature sensor that will
notify somebody of freezing conditions within the home.

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WARNING
Inhaling of fiberglass wool and/or ceramic fiber materials
is a possible cancer hazard. These materials can also
cause respiratory, skin and eye irritation.
Fiberglass wool and ceramic fiber materials
WARNING
Appliance 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 serious injury or loss of life 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 appliance.
The state of California has listed the airborne fibers of
these materials as a possible cancer hazard through
inhalation. When handling these materials, special care
must be applied.
First aid measures
- If eye contact occurs, flush eyes with water to
remove dust. If symptoms persist, seek medical
attention.
- If skin contact occurs, wash affected areas gently
with soap and warm water after handling.
Hazardous Material
Safety
Suppliers of ceramic fiber products recommend the
following first aid measures:
- Respiratory tract (nose and throat) irritation:
If respiratory tract irritation develops, move the
person to a dust free location.
- Eye irritation: If eyes become irritated, flush
immediately with large amounts of lukewarm water
for at least 15 minutes. Eyelids should be held away
from the eyeball to ensure thorough rinsing.
Do not rub eyes.
- Skin irritation: If skin becomes irritated, remove soiled
clothing. Do not rub or scratch exposed skin.
Wash area of contact thoroughly with soap and water.
Using a skin cream or lotion after washing may be
helpful.
- Gastrointestinal irritation: If gastrointestinal tract
irritation develops, move the person to a dust free
environment.
Suppliers of fiberglass wool products recommend the
following precautions be taken when handling these
materials:
- Avoid breathing fiberglass dust and contact with
skin and eyes.
- Use NIOSH approved dust/mist respirator.
- Wear long-sleeved, loose fitting clothing, gloves
and eye protection.
- Wash work clothes separately from other clothing.
Rinse washer thoroughly.
- Operations such as sawing, blowing, tear-out and
spraying may generate airborne fiber concentration
requiring additional protection.

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Safety
IMPORTANT
WARNING
Incorrect ambient conditions can lead to damage to
the heating system and put safe operation at risk.
Mechanical room conditions
Prevent the air from becoming contaminated by
homogenate hydrocarbons (e.g. as contained in paints
solvents or cleaning fluids) and excessive dust (e.g.
through grinding or polishing work). Combustion air for
the heating process, and ventilation of the boiler room
must be free of corrosive contaminants. To that end, any
boiler must be installed in an area that has no chemical
exposure. The list to the right indicates the main,
currently known sources.
Avoid continuously high levels of humidity (e.g. through
frequent drying of laundry).
Never close existing ventilation openings.
Components which are not tested with the heating
system may damage the heating system or affect its
functions. Installation or replacement may only be
carried out by a qualified heating contractor.
Sources of combustion and ventilation air contaminants
Areas likely to contain contaminants:
- New building construction
- Swimming pools
- Remodeling areas, hobby rooms
- Garages with workshops
- Furniture refinishing areas
- Dry cleaning/laundry areas and establishments
- Auto body shops
- Refrigeration repair shops
- Metal fabrication plants
- Plastic manufacturing plants
- Photo processing plants
- Beauty salons
Products containing contaminants:
- Chlorine-type bleaches, detergents and cleaning
solvents found in household laundry rooms
- Paint and varnish removers
- Hydrochloric acid, muriatic acid
- Chlorine-based swimming pool chemicals
- Spray cans containing chlorofluorocarbons
- Chlorinated waxes and cleaners
- Cements and glues
- Refrigerant leaks
- Calcium chloride used for thawing
- Sodium chloride used for water softening salt
- Permanent wave solutions
- Adhesives used to fasten building products and
other similar item
- Antistatic fabric softeners used in clothes dryers
Mechanical Room
IMPORTANT
Always follow the most up-to-date local, municipal and
building regulations and codes.
No combustible materials may be stored in the heating
room. The heating boiler may only be set up on a fire-
resistant and temperature-resistant floor. No temperature-
sensitive pipes or lines may be installed in the floor
beneath the heating boiler.
A sufficient supply of fresh air must be provided directly
from outdoors into the heating room. Induced ventilation
is necessary for heating rooms that are confined or
enclosed. See “Installation and Operating Instructions”
for more details.
The temperature in the heating room must not exceed
104°F (40°C) while the system is in operation
(in the area approx. 3 ft. (1 m) away from the boiler).
The temperature in the heating room must not fall below
50°F (10°C) while the system is in operation (measured
at the inner side of exterior walls).

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Combustion Air Supply
Codes
Provision for combustion and ventilation air must be made
in accordance with applicable local codes.
In the absence of local codes, use:
CSA B365-10, Installation Code for Solid Fuel Burning
Appliances and Equipment.
Always use latest edition codes.
WARNING
Failure to provide an adequate supply of fresh combustion
air can cause poisonous flue gases to enter living space.
Flue gases entering living space can cause carbon
monoxide poisoning which can result in severe personal
injury or loss of life.
WARNING
Never cover the boiler or store debris or other materials
near the boiler, or in any way block the flow of adequate
fresh air to the boiler. Never cover the combustion air
opening. Advise system operator/ultimate owner
accordingly.
WARNING
The boiler must not be located in areas or rooms where
chemicals are stored or aggressive vapors (i.e. bleach,
hair spray, methyl chloride, carbon tetrachloride or
perchloroethylene) or high dust levels or humidity levels
are present. Heat exchanger corrosion might occur and
reduce the lifetime of the boiler significantly. If above
criteria are not properly observed and boiler damage
results, any warranty on the complete boiler and related
components will be null and void.
General
This equipment requires fresh air for safe operation.
The boiler location must never be under negative pressure.
Exhaust fans, attic fans, or dryer fans may cause air to be
exhausted at a rate higher than air can enter the structure
for safe combustion.
The heating contractor shall ensure all of the following
requirements are met:
- An adequate supply of combustion air must be
available to ensure proper combustion.
- Ambient air temperatures must be maintained within
safe operating limits.
- When a damper is provided in any opening intended
to admit combustion air into the room within which
the appliance is installed, the damper shall be
interlocked to prevent any boiler from starting
before the damper is fully open.
- Each duct used to convey air from the outdoors
shall have:
1. a cross-sectional area throughout its length at
least equal to the free area of the inlet and outlet
openings which it connects,
2. making a provision for outside combustion air,
the intake shall not be less than 1 ft. (0.3 m)
above the anticipated snow level for the location.
- The heating contractor must check with local
authorities (municipal building department) for
combustion air requirements particular to the area.
See “Installation and Operating Instructions” for more
details.

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Components of the Biomass Boiler
Legend
1In-feed auger with isolating layer
2Drive for moving grate
3Igniter
4Controlled combustion air supply system
5Moving grate
6Drive for automatic de-ashing assembly with ash
container (optional)
7Combustion chamber
8Combustion chamber door
9Pneumatic cleaning system (optional)
qP Heat exchanger door
qQ Safety heat exchanger for thermal safety flush valve
qW Heat exchanger
qE Frequency-controlled flue gas exhaust blower
Maintenance

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Cleaning
Boiler
The heat exchanger, flue gas pipe, and chimney must be
cleaned regularly to remove accumulated creosote and ash.
Ensure that the heat exchanger, flue gas pipe, and
chimney are cleaned at the end of the heating season
to minimize corrosion during the summer months. The
appliance, flue gas pipe, and chimney must be in good
condition.
Regular cleaning and maintenance of the boiler system is
of the utmost importance to assure trouble-free operation
and to obtain the greatest possible output at the best
efficiency.
The cleaning intervals listed here are for wood chip fuel
with clinging bark with 0.8% ash content. The cleaning
intervals may vary, depending on the fuel, the amount
of fine matter and the operating conditions.
IMPORTANT
CAUTION
RISK OF INJURY - Shut the system off before beginning
any cleaning work. Be absolutely sure to wear protective
gloves, protective eyewear if required and use the cleaning
utensils that come with the system (danger of blow-ups,
burns and getting crushed)!
CAUTION
DANGER OF INJURY – be absolutely sure to turn OFF
main switch.
Never operate the boiler without the ash bin.
After each manual cleaning
of the heat exchanger:
Use ash rake to draw ash to
the front and remove.
After each manual cleaning
of the heat exchanger:
Open lid on both sides
and remove ash.
Approx. every 300 operating
hours:
Clean the light barriers and
inspection windows above
the in-feed auger, and also
opposite. Remove dust and
ash deposits in the openings.
Approx. every 300 operating
hours:
Open all the lids on the
insertion side or across from
the feed and remove ash.
Approx. every 300 operating hours:
Clean the light barriers and inspection
windows above the de-ashing auger
(optional), and also opposite. Remove
dust and ash deposits in the openings.
Approx. every 300 operating hours:
Clean the air vents for the burner trough
and remove remaining ash from the
combustion chamber.
IMPORTANT
With pneumatic cleaning system, disconnect the
compressed air line before opening the boiler door –
danger of injury!
With pneumatic cleaning system, after approx. 600
operating hours; without pneumatic pipe cleaning system,
after approx. 300 operating hours:
Open the heat exchanger door and clean all heat
exchanger tubes with a wire cleaning brush.
Check the level of the ash bin regularly and empty the bin
before it is completely full.

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Cleaning (continued)
Installing the displacement rods
Insert the displacement rods into the heat exchanger
tubes with the thick end first. Push until they are flush
with the edge of the tube. Tolerance +/- a” (5 mm).
Remove the displacement rods with a pair of pliers, as
shown above. The heat exchanger should be cleaned
at the intervals prescribed so that performance and
efficiency are maintained and the displacement rods
can be easily removed.
Removing the displacement rods
RISK OF INJURY: Shut the system off before starting
any cleaning. Be absolutely sure to wear protective
gloves, protective eyewear if required and use the
cleaning tools that come with the system (danger of
blow-ups, burns and getting crushed)!
CAUTION
Heat exchanger tube displacement rods
The displacement rods improve the heat transmission in the heat exchanger tubes and reduce the temperature of
the exhaust gas, thus improving the efficiency of the heating system. They have to be taken out to clean the heat
exchanger tubes and put back in after cleaning.
Note: Vitoflex 300-UF 390 and 530 do not have displacement
rods.
Maintenance

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Cleaning (continued)
Pneumatic cleaning system (optional)
- Operation and maintenance of the compressor
(optional) according to the manual that comes with
the system.
- For a field supplied air compressor, the compressor
has to be suited for continuous operation or be
secured against continuous operation (e.g. timer for
limiting running time).
- Continuous operation of the compressor indicates
leakage in the air system. Check air supply line and
valves for leakage.
IMPORTANT
RISK OF INJURY: Shut the system off before starting
any cleaning. Be absolutely sure to wear protective
gloves, protective eyewear if required and use the
cleaning tools that come with the system (danger of
blow-ups, burns and getting crushed)!
CAUTION
Flue gas cyclone (optional)
The flue gas cyclone minimizes dust emissions and is
designed as a multi-cyclone with an axial function.
The cyclone is completely insulated and provided with a
total of three lids for cleaning. The untreated exhaust flue
gas chamber is cleaned via the cleaning lid on the side.
The clean exhaust flue gas chamber is cleaned via the top
or rear cleaning lid (unused blower connection).
The ash container, which is provided with a trolley,
connects to the cyclone by quick-action fasteners and
easily moves out for emptying. The flue gas exhaust
blower can be mounted either on top or on the side, as
desired.
After approx. 1000 operating hours:
Disconnect the power, unscrew the butterfly nuts,
pull out the motor with impeller and clean the assembly
with a broom or wire brush.
After every cleaning of the boiler heat exchanger:
Open the side lids and clean the guide blades of
the cyclone with a hand-brush.
Check the level of the ash bin regularly and
empty the bin before it is completly full.
Never operate the boiler without an ash bin!

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Vitoflex 300-UF Service & Maintenance
Cleaning (continued)
Flue gas re-circulation system (optional)
WARNING
A mixture of emissions and air that may contain carbon
monoxide (CO) and other toxic odorless gases is produced
inside the re-circulating flue gas piping system. Its pressure
is slightly above atmospheric.
Therefore the correct assembly of the cleaning lids must
be checked and the system must be checked for leaks
each time the system has been cleaned (when the
re-circulating flue gas exhaust blower is in operation and
the flaps are closed, no gas may escape).
Approx. every 4000 operating hours:
Clean the secondary air blower.
Approx. every 1000 operating hours:
Clean the re-circulation flue gas exhaust blower.
After around 1800 operating hours (annually):
Checks for leaks must be repeated each year
so that any possible wear on the seals,
particularly in the area of the maintenance
covers, may be recognized and corrected in time.
Approx. every 4000 operating hours:
Clean the re-circulation flue gas line
RISK OF INJURY: Shut the system off before starting
any cleaning. Be absolutely sure to wear protective
gloves, protective eyewear if required and use the
cleaning tools that come with the system (danger
of blow-ups, burns and getting crushed)!
CAUTION
Maintenance

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Vitoflex 300-UF Service & Maintenance Maintenance
When storage facilities for wood are required, the wood
should be kept at least 5 ft. (1.5 m) from the heating
appliance.
All geared motors on the feed systems are maintenance-free.
- A change of lubricant and/or oil is recommended
every 20,000 operating hours or every three years.
- Re-lubricate flange bearings and other lubricating
points regularly with lithium soap grease.
- Check chain drives for wear and, if necessary,
tighten them up and lubricate with chain oil.
- Check all bolts for tightness.
- Once a year check the extraction components
in the silo and/or bunker for damage and soiling.
Remove any foreign matter.
IMPORTANT
Feed Systems
Never use inflammable lubricants!
Funnel extraction system (AP/APS):
Lubricate the gasket between the extraction casing and
the geared motor and universal joint for the auger.
If a fuel hopper is installed, do not alter equipment in
any way. May be connected to an existing boiler or solar
system.
RISK OF INJURY: Shut the system off before starting
any cleaning. Be absolutely sure to wear protective
gloves, protective eyewear if required and use the
cleaning tools that come with the system (danger of
blow-ups, burns and getting crushed)!
CAUTION
IMPORTANT
Note: Viessmann recommends the installation of carbon
monoxide detector(s) inside the fuel storage area.
WARNING
The wood chip/pellet storage room must be adequately
and permanently ventilated. Ensure the door or latches
are securely locked open during presence in the room.
No smoking, fires or open flames are permitted.
The fuel storage area/room must be designed, operated
and maintained to national, provincial and local codes and
requirements.

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Vitoflex 300-UF Service & Maintenance
Shutdown
Boiler
Heat exchanger:
- When the Vitoflex 300-UF is not in operation for a
long period (such as for summer breaks), be sure to
carefully clean the heat exchanger with a steel brush
as required.
- If the heating room is moist or there is any other
atmosphere that promotes corrosion (e.g. poor
ventilation, residual enamel near the heating room,
etc.), spray the heat exchanger tubes with biodiesel
after cleaning.
- If there is a danger of frost, empty the heating
system or add antifreeze.
Extraction and conveyance systems
When the Vitoflex 300-UF is not in operation for a long
period (such as for summer breaks), it is recommended to
empty the fuel extraction and conveyance system of all
fuel to avoid corrosion of the equipment and decay of the
wood fuel. Refill with new fuel after checking the system
and before starting the boiler.
Control system
Even when the Vitoflex 300-UF is not in operation for long
periods, the power supply to the control system should
not be interrupted (do not turn off the main switch).
- The “intermittent control system” switches on the
boiler pump for five seconds every 24 hours.
This prevents the pump from jamming during long
stand stills and prevents expensive repairs.
- Prevent the formation of condensation in the oxygen
sensor.
- Extend the service life of the backup battery.
Replacing the backup battery
The backup battery is built in beneath the removable lid
on the control module (type Panasonic Lithium BR2330).
It is for backing up the time, date and settings.
Note: The battery needs replacing every five years.
DO NOT disconnect the main power or turn off the
main switch while changing the battery.
Ash disposal
- Ashes should be stored in covered metal containers
on non-combustible floors away from combustible
material.
- Comply with customary laws and local regulations
on ash disposal.
Disposal of the boiler
- Switch off the Vitoflex 300-UF by pressing the boiler
off button. When the burn-out has taken place, and
the boiler has cooled down, turn off the main switch.
- Disconnect the power supply to the control cabinet.
- Close the supply and return valves.
- Open the drain valve on the back of the boiler and
drain the water.
Only a qualified heating contractor may drain the boiler
and dismantle the connections to the heating system.
- Disconnect the supply pipe and return pipe from the
boiler.
Instructions regarding removal
Personnel removing equipment must be aware of the
risks and use suitable safety precautions.
Waste disposal
- Comply with customary laws and local regulations on
waste disposal.
- Contact a disposal company to dispose and recycle
waste in a environmental friendly way.
DANGEROUS VOLTAGE!
Only a licensed electrician is allowed to disconnect and
dismantle the connection to the electrical network.
CAUTION
IMPORTANT
Maintenance