Viessmann KOB PYROT KRT SERIES Instruction manual

Technical Data Manual
for use by engineers and heating contractors
5443 109 v1.9 05/2013
Pyrot with its patented rotating combustion chamber
design, features the industry’s most advanced combustion
technology. A feed auger continuously moves the wood
fuel onto a moving grate where gasification takes place.
The combustible gases blend with precisely controlled
secondary air, resulting in a complete combustion with
ultra low emissions.
Max. output: 150 to 540 kW (512 to 1843 MBH)
Min. output: 45 to 140 kW (154 to 478 MBH)
Pyrotr
Product may not be exactly as shown
Wood-fired Boiler
KRT 150 to KRT 540 Series

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5443 109 v1.9
Pyrot Technical Data
Pyrot
Product Information
Codes
CSA B366.1-M91
Solid Fuel Fired Central Heating Appliances
CSA C.22.2#3-M88 (R2004)
Electrical Features of Fuel Burning Equipment
UL2523
Solid Fuel-Fired Hydronic Heating Appliances, Water
Heaters and Boilers
CSA B365-01
Installation Code for Solid Fuel Burning Appliances
and Equipment
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.
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.
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.
Specifications
Fully-automatic rotating combustion wood-fired boiler
5 models from 512 to 1843 MBH
For dry wood fuels with max. water content of 35%
Efficiency: 85%
Available for 30 or 60 psi max. operating pressure
Benefits at a glance
High efficiency with advanced combustion technology,
triple-pass heat exchanger and modulating output
control (turndown ratio 4:1)
Maximum heat transfer with triple-pass heat
exchanger design.
High efficiency and ultra-low emissions with precisely
controlled primary and secondary air.
Automatic ignition device limits idling and saves fuel.
Low maintenance with fully-automatic de-ashing,
optional pneumatic cleaning system and flue gas
de-duster.
Advanced safety equipment ensures safe and reliable
operation.
Custom design of your system by our team of experts.
Available as convenient portable boiler enclosure.

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5443 109 v1.9
Pyrot Technical Data
Boiler Description
Description
The PYROT Rotating Combustion System (patent no: EP
0 905 442 B1) was developed for automatic combustion
of all dry to moist wood fuels (remnant wood, pellets and
forest wood chips to max. W35-40, see section “Wood
Fuel Requirements”. The PYROT Rotating Combustion
System is characterized by high efficiencies and perfect
combustion at all load levels. The PYROT Boiler Plant has
been built to ASME Sec. IV and has CRN for Canada. It
is tested and approved to the applicable CSA / UL safety
standards.
Function:
- The in-feed auger conveys the wood fuel diagonally
from below into the fire box. The holding devices for
the back-burn sensor and the thermal extinguishing
valve are situated on the in-feed auger. Above the in-
feed auger, there is a metering container with a light
barrier to ascertain the level of the fuel insulating layer
required.
- The wood fuel is ignited automatically by an electric
heat gun, at the time of the boiler start. The gasification
of the fuel is carried out on a feed grate moved by a
worm-geared motor. The ash falls in an ash bin below.
An automatic de-ashing system is optional. The fire box
is heavily insulated and lined with fire clay refractory
elements.
- The combustion gases rising from the fire box are swept
up by the rotating secondary airflow brought to bear
from the rotation blower and burned out completely in
the round combustion chamber. The thermal energy
from the combustion gases is transmitted to the boiler
water in horizontal heat exchanger tubes. The combustion
chamber is heavily insulated and provided with excellent
access through the boiler door in the front.
- A flue gas re-circulation system reduces the temperature
in the fire box while maintaining the highest possible
degree of efficiency. This increases the service life of
the un-cooled refractory elements in the gasification
zone. With the basic setting, the ratio of re-circulated
gas to fresh air is precisely adjusted according to the
amount of wood fuel that is burned. A mechanical
adjustable damper provides a constant ratio of the quantity
of re-circulated gas to fresh air over the entire output
range.
- The flue gas blower is specially designed for wood
heating operation and is very quiet. The motor has a
solid, heat resistant design with a heat dissipation hub
and is spring supported. The blower casing has a round
intake port and a round blowout nozzle. Installation
is possible on the top, side or rear of the flue gas
collector within 360° rotation.
General Information
Boiler Description
Supplied with:
- Boiler with rotating combustion chamber and tube heat
exchanger including supply and return temperature sensors
- Fire box with moving grate and light barriers for ember
monitoring
- Automatic ignition blower
- In-feed auger including insulating layer, safety end
switch for maintenance lid, back-burn temperature
sensor, extinguisher valve with strainer, extinguisher
water container with mounting bracket
- Set of displacement rods
- Flue gas re-circulation system
- Flue gas blower including flue gas temperature sensor
and oxygen sensor
- Draft damper for installation in the flue gas pipe
- Boiler cleaning tools for the fire box, combustion
chamber and tube heat exchanger
- Installation fittings including pressure relief valve, drain
valve, low water cut off, safety temperature limiter,
temperature and pressure gauges
Customer supplied:
- Counter flanges for the boiler supply and return
- Piping to the mixing valve, boiler pump and hot water
storage tank
- Piping for the safety heat exchanger
- Wiring to the control panel
Accessories for PYROT Rotating Combustion System:
- Flue gas de-duster 24 USG (90 L)
- Metal mesh filter
- Automatic de-ashing system in bin, 63 USG (240 L)
- Automatic de-ashing in bin, 211 USG (800 L)
- Automatic de-ashing in base container
- Pneumatic cleaning system
- Operating pressure 30 or 60 psi
- Two-stage in-feed auger
- Insulation for flue gas re-circulation line
- Thermal safety flush valve
- Slide valve / Rotary valve
- Boiler pump and boiler mixing valve
- Ecotronic control system options:
- 3 sensor hot water storage tank management system
- External control module for field supplied extraction
system
- Output module / Input module
- Input module 0-10V
- ModBus
- BacNet gateway
- Visualization

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5443 109 v1.9
Pyrot Technical Data
Precautions must be taken to avoid accidents and injury
during the transportation of the boiler.
Only hoist the boiler when it is entirely empty of water,
fuel and ash.
Lifting
A number of lifting lugs will be provided on each boiler
and tube heat exchanger where lifting gear may be
attached. A tie bar is required to lift the boiler by the
boiler supply and boiler return flanges.
Minimum clearances to walls for installation and
maintenance work must be observed. Anti-vibration
boiler supports may be used if anti-vibration measures
are required.
Pyrot 150 - 300:
Hoist by the lifting lug.
Pyrot 400 - 540:
Hoist by boiler supply and boiler return flanges using
a lifting lug.
IMPORTANT
WARNING
Follow instructions for proper installation.
For wood-fired installations:
This wood-fired boiler must be installed in accordance
with local codes if any; if not, follow B 365-01,
Installation Code for Solid-Fuel Burning Appliances
and Equipment.
General Information
Transport and Installation
ALifting lugs

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5443 109 v1.9
Pyrot Technical Data
Standard delivery condition
The standard delivery condition of the Pyrot boiler
includes pre-assembled components as well as
components that need to be assembled by the contractor
in the field.
Components that are attached to the boiler at time of
delivery:
- The combustion chamber is mounted to the fire box
- Boiler is fully bricked
- Boiler door is mounted to the combustion chamber
including secondary air rotary blower
- Primary air vents are attached to the fire box
- Flue gas collector is attached to the tube heat
exchanger
- Pneumatic cleaning system (optional) is attached to
the flue gas collector
Measurements for the fire box as standard delivery condition
Boiler model KRT150 KRT220 KRT300 KRT400 KRT540
Minimum size
door
47a in. x 78c in.
(1200 mm x
2000 mm)
59 in. x 88b in.
(1500 mm x
2250 mm)
59 in. x 88b in.
(1500 mm x
2250 mm)
70c in. x 98b in.
(1800 mm x
2500 mm)
70c in. x 98b in.
(1800 mm x
2500 mm)
Minimum ceiling
opening (W x H)
47a in. x 112a in.
(1200 mm x
2850 mm)
59 in. x 112a in.
(1500 mm x
2850 mm)
59 in. x 126 in.
(1500 mm x
3200 mm)
70c in. x 130 in.
(1800 mm x
3300 mm)
70c in. x 137c in.
(1800 mm x
3500 mm)
Minimum ceiling
opening including
pneumatic
cleaning system
47a in. x 128 in.
(1200 mm x
3250 mm)
59 in. x 128 in.
(1500 mm x
3250 mm)
59 in. x 141c in.
(1500 mm x
3600 mm)
70c in. x 145c in.
(1800 mm x
3700 mm)
70c in. x 153b in.
(1800 mm x
3900 mm)
Delivery Condition
General Information
Components that are not attached or installed to the
boiler at time of delivery (scope of the contractor):
- Electrical components which include temperature
sensors, oxygen sensor, light barriers for the fire box,
ignition blower, low water cut off, safety temperature
limiter, and light barriers for the complete extraction
system
- All wiring to the control cabinet
- Installation fittings which include pressure relief valve,
drain valve, temperature and pressure gauges
- Drive for the fire box grate is detached
- De-ashing system (optional) and drive for the de-ashing
system
- Air compressor (optional) and connection to the
pneumatic cleaning system (optional)
- The flue gas blower is not attached to the flue gas
collector
- Re-circulation system and insulation (optional)
- Flue gas de-duster (optional) comes in two pieces
- The in-feed auger is detached from the fire box
- Fire extinguishing system for the in-feed auger
- Slide valve (optional) or rotary valve (optional)
- All components of the extraction system (optional),
welding for flanges and support legs required
- Glass fiber insulation between any auger connections

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5443 109 v1.9
Pyrot Technical Data
Boiler model KRT150 KRT220 KRT300 KRT400 KRT540
Minimum size
door
35b in. x 49a in.
(900 mm x
1250 mm)
46 in. x 61 in.
(1170 mm x
1550 mm)
46 in. x 61 in.
(1170 mm x
1550 mm)
55 in. x 67 in.
(1400 mm x
1700 mm)
55 in. x 67 in.
(1400 mm x
1700 mm)
Minimum
ceiling opening
(W x H)
39a in. x 102a in.
(1000 mm x
2600 mm)
49a in. x 103a in.
(1250 mm x
2620 mm)
49a in. x 118 in.
(1250 mm x
3000 mm)
59 in. x 122 in.
(1500 mm x
3100 mm)
59 in. x 130 in.
(1500 mm x
3300 mm)
Special delivery condition (partially disbanded)
For special circumstances like restricted space to bring
the boiler into the heating room, the size of the boiler
can be reduced by detaching additional components
to the ones as described in section “Standard delivery
condition”. The assembly of these components require
additional assembly time of approximately 6 hours.
Measurements of the largest part for reduced boiler size
Special delivery condition (fully disbanded)
For special circumstances like heavily restricted space
to bring the boiler into the heating room, the size of the
boiler can be reduced by detaching additional components
to the ones as described in section “Standard delivery
condition” and “Special delivery condition partially
disbanded”. The assembly of these components require
welding and additional assembly time of approximately
20 hours.
Measurements of the largest part for reduced boiler size
Boiler model KRT150 KRT220 KRT300 KRT400 KRT540
Minimum size
door
35bin. x 49ain.
(900 mm x
1250 mm)
46 in. x 59 in.
(1170 mm x
1500 mm)
46 in. x 59 in.
(1170 mm x
1500 mm)
55 in. x 67 in.
(1400 mm x
1700 mm)
55 in. x 67 in.
(1400 mm x
1700 mm)
Minimum
ceiling opening
(W x H)
39ain. x 85 in.
(1000 mm x
2160 mm)
49ain. x 85cin.
(1250 mm x
2180 mm)
49ain. x 98c in.
(1250 mm x
2510 mm)
59 in. x 96bin.
(1500 mm x
2450 mm)
59 in. x 110 in.
(1500 mm x
2800 mm)
Delivery Condition (continued)
General Information
The following additional objects will be delivered
disbanded:
- The combustion chamber and the fire box are separate
- No brickwork inside the combustion chamber and fire
box
- No insulation and panels are attached to the
combustion chamber
The following additional objects will be delivered
disbanded:
- The tube heat exchanger is a separate piece
- The flue gas collector is detached from the tube heat
exchanger
- The boiler door is detached from the tube heat
exchanger (welding required)

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5443 109 v1.9
Pyrot Technical Data
Wood Fuel Requirements
Allowed fuels
- Forest wood and plantation wood (complete untreated
trees and trunk wood):
Mature wood from trunks and branches, untreated,
chopped to chips
- Compressed wood, pellets conforming to standards,
as per CAN/CSA-B366.1-M91, size P1, P2, P4.
Untreated wood with limited bark content, compressed by machine and calibrated
Fuel Minimal Diameter Maximal Diameter
P1 - Pellets Small --- ein. (10 mm)
P2 - Pellets Medium ein. (10 mm) cin. (20 mm)
P4 - Briquettes (Pellets Large) cin. (20 mm) 2bin. (60 mm)
Consequence of overstepping particle size:
- Increased maintenance because of a substantially higher
risk of malfunction
- Shortened service life of the conveyor augers and drives
CAUTION
Chips have to pass through a 1 in. (25 mm) sieve,
additionally, a fraction of max. 5% of the fuel with a
cross-section of max. cin² (500 mm²) up to a length
of max. 6ain. (160 mm) can be tolerated.
- Wood with an increased proportion of bark, tree
cuttings from roadside trees (untreated):
Wood remnants from the forestry and sawmill industries
or from landscape conservation (likelihood of elevated
ash content).
- Remnants from derived timber products:
Usually a mixture of untreated and treated wood in the
form of shavings from processing machinery and chips
from choppers.
If different fuels are used, Viessmann will not assume
any liability for the functioning or service life of the boiler
plant. Refer to the “Warranty” section in the General
Terms and Conditions of Delivery.
- Burn wood only
- Do not use chemicals or fluids to start fire.
- Do not burn garbage, gasoline, naphtha, engine oil, or
other inappropriate materials.
IMPORTANT
General Information
The PYROT is only suitable for burning fuels listed in this
section.
A prerequisite for approval is of a fuel by Viessmann is the
approval for the fuel by the responsible public authorities.
Warranty claims for Viessmann Biomass boilers are
excluded if the following fuel conditions are not met.
Size of briquettes:
- Fraction of one-offs. max. 5% with cross-section of
max. cin2(500 mm2) up to a length of max. 6ain.
(160 mm).
- Frayed surface by chopping tools (shredders) or slow-
running choppers.
- Briquettes, diameter max. 2ein. (60 mm).
- Used wood:
This is untreated wood that has been used prior to its
energetic utilization (e.g. pallets). It is reduced
in size by shredders for thermal utilization. The metal
parts have to be removed by magnetic separators.
Size of Wood Chips as per CAN/CSA-B366.1-M91, Grade C7
Total mass 100% G 30 Fine G 50 Medium
Coarse percentage max. 20% Max. cross-section in.2(cm2)b(3) c(5)
Max. length in. (cm) 3g(8.5) 4c(12)
Coarse sieve nominal mesh width in. (mm) f(16) 1a(31.5)
Main percentage 60 to 100% Medium sieve nominal mesh width in. (mm) d(2.8) a(5.6)
Percentage of fines
(incl. ultrafine content) max. 20%
Fine sieve nominal mesh width in. (mm) 1/25 (1) 1/25 (1)

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5443 109 v1.9
Pyrot Technical Data
Wood Fuel Requirements (continued)
Maximum water content
The maximum allowable water content of the fuel for
Pyrot systems is limited to 35%.
The water content impacts the maximum boiler output.
Non-wood fuels
Non-wood fuels, even if consisting of biomass, such as
needles, foliage, grain, straw, fruit pits, etc., are unsuited
as fuel for boiler operation and may not be used.
Limitation super fines & dust [wood particles smaller than
1
/32 in. (1.0 mm)]
Max. 10.0% of the total mass; if fuel does not comply
with this limit the following process may occur:
- Temperature peaks
- Slag formation
- Even higher temperature
- This process leads to damage by overheating and
can affect refractory materials.
Elevated values are especially critical for remnant wood in
combination with elevated values of Chlorine and Sulphur.
General Information
Suitable fuel types for Pyrot systems
- Bulk density (S) in kg/m³ [lb/ft³], water content (W) in %,
size C1, C7, P1, P2, P4 as per CAN/CSA-B366.1-M91.
Note: Fuel for Pyrot systems allow for a max. of 35%
water content (W).
Saw dust
Fuel code Bulk Density kg/m³ [lb/ft³] Water content % Fuel Size Description
aS130 [8.1] W10 to W20 C1 Sawdust, untreated (planing shop)
b1 S200 [12.5] W20 to W35 C1 Sawdust, untreated (sawmill)
c2 S250 [15.6] W35 to W50 C1 Sawdust, untreated (sawmill)
Wood chips
Fuel code Bulk Density kg/m³ [lb/ft³] Water content % Fuel Size Description
b2 S200 [12.5] W20 C7 Forest wood chips, soft, untreated
c1 S250 [15.6] W20 to W35 C7 Forest wood chips, soft, untreated
d1 S300 [18.7] W20 to W35 C7 Forest wood chips, soft/hard, untreated
d2 S300 [18.7] W35 to W50 C7 Forest wood chips, soft, untreated
e1 S350 [21.8] W20 to W35 C7 Forest wood chips, hard, untreated
e2 S350 [21.8] W35 to W50 C7 Forest wood chips, soft/hard, untreated
f1 S400 [24.9] W35 to W50 C7 Forest wood chips, hard, untreated
Shavings and chips
Fuel code Bulk Density kg/m³ [lb/ft³] Water content % Fuel Size Description
gS130 [8.1] Less than W15 C7 Shavings & chips from wood remnants,
dry, mixed
hS200 [12.5] Less than W15 C7 Shavings & chips from wood remnants,
dry, mixed
iS250 [15.6] Less than W15 C7 Shavings & chips from wood remnants,
dry, mixed
Pellets and briquettes
Fuel code Bulk Density kg/m³ [lb/ft³] Water content % Fuel Size Description
jS350 [21.8] Less than W15 P4 Briquettes from wood remnants cin. (20
mm) to max. 2 in. (60 mm)
k1 S650 [40.6] Less than W10 P1 untreated up to ein. (10 mm)
k2 S650 [40.6] Less than W10 P2 untreated ein. to cin. (11 mm to 20 mm)
Note: For size of wood chips, see page 7.

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5443 109 v1.9
Pyrot Technical Data
Wood Fuel Requirements (continued)
If fuel does not comply with these limits, there is a risk
of corrosion within the heat exchanger and early sintering
and melting of the ash which leads to:
- Shortened life of the tube heat exchanger
- Increased maintenance costs (firing, boiler door)
The maintenance instructions need to be complied with
in order to avoid a process, which will increasingly cause
damage to the boiler.
If maintenance instructions are not complied with the
following process may occur:
- Cinders change the airflow
- Temperature peaks
- More slag is produced
- More cinder builds up and changes the airflow more
This process leads to damage by overheating and may
affect refractory materials.
Additives in remnant and used wood have to be free of
heavy metals and halogen compounds.
Content limits for non-combustible substances
- No wood fuels may contain any foreign bodies, such
as pieces of metal, stones, masonry remnants or plastics.
The following limits (per lb/kg of dry fuel) of contained
non-combustible substances apply [ash analyzed at a
temperature of 1500° F (815° C)]:
Substance Limit Comparative value untreated forest wood
Chlorine (Cl) max. 300 ppm (300 mg/kg) 10 ppm (10 mg/kg)
Sulphur (S) max. 1000 ppm (1000 mg/kg) 120 ppm (120 mg/kg)
Total Cl, S max. 1000 ppm (1000 mg/kg) 130 ppm (130 mg/kg)
Ash content, total max. 0.25 oz/lb (15.0 g/kg) 0.08 oz/lb (5.0 g/kg)
Alkali oxides in the ash (K2O and Na2O) max. 0.016 oz/lb (1.0 g/kg) 0.006 oz/lb (0.35 g/kg)
Sintering point of the ash min. 1800° F (1000° C) approx. 2200° F (1200° C)
General Information
Other information
- Ash and cleaning:
Untreated wood without bark produces less than 0.5%
ash of the fuel mass supplied. All the specifications
regarding cleaning are based on untreated wood with
bark attached with an ash amount of 0.8% of the fuel
mass.
If the ash content is higher and/or the ash melting
point is lower, increased maintenance and/or cleaning
are required.
-Changing fuels:
A substantial change in fuel quality, such as bulk
density, water content, dust proportion or ash content
might require a manual correction of the firing
parameters (see Operating section).

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5443 109 v1.9
Pyrot Technical Data
The PYROT Rotating Combustion system is equipped
with a flue gas blower.
This boiler must be properly vented. Use a vent material
certified for use with solid-fuel fired equipment.
This boiler shall be connected to:
a) a masonry chimney conforming to local regulations
or, in the absence of such regulations, to the requirements
of the National Building Code.
b) a certified factory-built chimney (refer to the NFPA 211
standard).
A flue pipe serving this boiler shall be constructed of steel
or other suitable material with a melting point of not less
than 2000° F (1100° C).
Do not use galvanized steel.
IMPORTANT
Customers must ensure that there is a supply of water
independent of the electrical supply. This design ensures
that in case of a power failure, the boiler will be reliably
cooled by the thermal run-off safety valve.
Power Failure Provision
Safety
Venting Requirements
For installations in Canada:
The boiler venting system must be tested and listed by
a Nationally Recognized Testing Lab such as ULC/CSA
for solid fuel burning appliances.
The PYROT rotating combustion system is output-
controlled within a range from 30%-100% of the rated
boiler output. This produces flue gas temperatures from
min. 212° F (100° C) to max. 482° F (250° C).
An insulated chimney should be provided to prevent sooting.
The distance from the flue gas blower to the chimney
should be as short as possible. 90° elbows should be
avoided if possible. Flue gas pipes of more than 3 ft. (1 m)
in length must be insulated.
The connection to the chimney should be made such that
it rises at an angle of 30°- 45° (to prevent excess ash
accumulating in the lateral section of the vent pipe).
The flue gas line, including the lead-in into the chimney,
must be gas-tight.

11
5443 109 v1.9
Pyrot Technical Data
The minimum distance to the walls and ceiling required
according to the table of dimensions for proper cleaning
and maintenance of the boiler must be complied with.
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.
Safety
Mechanical Room
Foundation dimensions
Boiler model KRT- 150 220 300 400 540
a in. (mm) 6113 /1 6 (1570) 8011 /1 6 (2050) 8011 /1 6 (2050 967 /8(2460) 967 /8(2460)
b in. (mm) 34a(870) 45a(1150) 45a(1150) 54c(1390) 54c(1390)
c in. (mm) 24e(620) 26c(680) 26c(680) 31b(800) 31b(800)
d in. (mm) 1123 /1 6 (2850) 123a(3130) 142a(3613) 147d(3738) 161b(4103)
e in. (mm) 20b(520) 20b(520) 28b(723) 17f(448) 21e(543)
f in. (mm) 29d(740) 29d(740) 34f(880) 3713 /1 6 (960) 4311 /1 6 (1095)
g in. (mm) 34a(870) 45a(1150) 45a(1150) 54c(1390) 54c(1390)
h in. (mm) 97 /8(250) 97 /8(250) 97 /8(250) 97 /8(250) 97 /8(250)
The load-bearing capacity of the heating room floor must
be designed for the weight of the system plus filling with
water and fuel. The load-bearing capacity of the floor in
the area of the boiler bearing surface must be 512 lb/ft²
(2500 kg/m²).
IMPORTANT
Always follow the most up-to-date local, municipal and
building regulations and codes.
x Fuel feed to the boiler
y Heat-resistant floor
Surface medium grey Boiler supporting surface
Ensure the mechanical room complies with the requirements
in these instructions.
Viessmann recommends the installation of an additional
electrical disconnect switch and a fuel shut-off valve (if
possible) outside the mechanical room or enclosed area
of installation.
A separate, dry heating room must always be provided for
the PYROT rotating combustion system. No combustible
materials may be stored in the heating room. The heating
boiler may only be set up on a fire- and temperature-
resistant floor.
No temperature-sensitive pipes or lines may be installed
in the floor beneath the heating boiler.
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).

12
5443 109 v1.9
Pyrot Technical Data
Combustion Air Supply
Safety
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.
General
This equipment requires fresh air for safe operation
and must be installed ensuring provisions for adequate
combustion and ventilation air exist.
Whenever possible, install boiler near an outside wall so
that it is easy to duct fresh air directly to the boiler area.
The boiler location must never be under negative pressure.
Exhaust blowers, attic blowers, or dryer blowers 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 burner 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.
Codes
Provision for combustion and ventilation air must be made
in accordance with applicable local codes.
In the absence of local codes, use:
CSA B365-01, Installation Code for Solid Fuel Burning
Appliances and Equipment.
Always use latest edition codes.
Confined spaces
When a furnace or boiler is enclosed in a space that has
a volume less than 20% of that to be heated by the
appliance, the space shall:
a) have a permanent opening or openings for natural air
circulation with a minimum net free area of 1.5 in² /
1000 Btu/h (3300 mm² / kW) input, and
b) connect to another space or spaces such that the total
volume of air available for natural air circulation is at
least 30% of the total volume to be heated by the
appliance.
The minimum dimension of any opening specified in item
(a) shall be no less than 1 in. (25 mm) The lower edge of
at least one opening shall be located within 1.5 ft. (0.5 m)
of the floor of the enclosed space, and the upper edge of
at least one opening shall be located within 1.5 ft. (0.5 m)
of the ceiling of the enclosed space.
Note: The intent of this Clause is to allow either one long
vertical opening or two shorter horizontal openings,
one high and the other low, to allow for air circulation
to prevent overheating of the appliance.
Unconfined spaces
Where the boiler is located in an unconfined space in
a building having insufficient infiltration, additional air
for combustion and ventilation shall be obtained from
outdoors or from spaces freely communicating with the
outdoors. Under these conditions, permanent opening(s)
shall be provided so that the total air received through
these openings will be at least as much as would be
admitted by openings having a total free area of 1 in² /
5,000 Btu/h or (450 mm² / kWh) of the total input rating
of all wood-fired appliances.
Louvers and grilles
In calculating free area as specified, consideration shall be
given to the blocking effect of louvers, grilles, or screens
that protect openings. Screens shall be no smaller than
¼ in. (6 mm) mesh and shall be readily accessible for
cleaning. If the free area through a design of louver or
grilles is known, it shall be used in calculating the size of
opening required to provide the free area specified. If the
design and free area are not known, it shall be assumed
that wood louvers have 20 - 25% free area and metal
louvers and grilles have 60 - 75% free area.

13
5443 109 v1.9
Pyrot Technical Data
Technical Data
Boiler model KRT- 150 220 300 400 540
Maximum output MBH (kW) 512 (150) 751 (220) 1024 (300) 1365 (400) 1843 (540)
Minimum output1MBH (kW) 154 (45) 205 (60) 273 (80) 341 (100) 478 (140)
Efficiency 85%
Fuel moisture content2% W 40
Size of wood chips3G 30 / G 50 as per CAN/CSA-B366. 1-M91
Flue gas figures
Connection flue gas pipe 7A
Mass flow rate; W5; O26%
Volume flow; W5; O26%; 150º C (302º F)
Mass flow rate; W35; O28%;
Volume flow;W35; O28%; 150° C (302º F)
Average flue gas temperature at full load4
Average flue gas temperature at partial load4
Chimney draft required
in. (mm)
lb/s (g/s)
ft³/s (m³/s)
lb/s (g/s)
ft³/s (m³/s)
°F (°C)
°F (°C)
Pa
97/8(250)
0.18 (80.4)
3.1 (0.09)
0.24 (106.9)
4.2 (0.12)
97/8(250)
0.26 (117.9)
4.9 (0.14)
0.35 (156.9)
6.7 (0.19)
117/8(300)
0.35 (160.8)
6.7 (0.19)
0.47 (213.9)
8.8 (0.25)
137/8(350)
0.47 (214.4)
8.8 (0.25)
0.63 (285.2)
12.0 (0.34)
137/8(350)
0.64 (289.44)
12.4 (0.35)
0.85 (385.1)
16.2 (0.46)
320 (160)
266 (130)
±0
Electrical connections
Electrical connections, total
Ignition device
Flue gas blower
Articulated head blower
In-feed auger
Grate drive unit
Electric power consumption at full load
Electric power consumption at partial load
kW
kW
kW
kW
kW
kW
kW
kW
2.67
1.6
0.55
0.12
0.37
0.03
1.032
0.355
2.85
1.6
0.55
0.12
0.55
0.03
1.108
0.369
3.6
1.6
0.75
0.12
1.1
0.03
1.521
0.434
3.98
1.6
1.1
0.12
1.1
0.06
1.868
0.480
3.63
1.6
1.1
0.12
0.75
0.06
1.753
0.460
Heating
Water side resistance (diff. 27° F/15 K)
Boiler water volume
Heating surface
Volume on heating gas side
Volume of ash container for grate ash
Volume of ash container for flue gas de-duster
Test pressure5
Maximum allowable working pressure (water)5
Maximum water temperature
Minimum return temperature
“wc (mbar)
USG (L)
ft² (m²)
USG (L)
USG (L)
USG (L)
psi (bar)
psi (bar)
°F (°C)
°F (°C)
13 (38)
114 (430)
116.3 (10.8)
99 (374)
8 (32)
30 (76)
209 (790)
172.3 (16.0)
197 (744)
12 (45)
16 (42)
238 (900)
222.9 (20.7)
233 (883)
15 (55)
11 (29)
350 (1330)
310.1 (28.8)
354 (1340)
20 (75)
22 (56)
399 (1510)
424.1 (39.4)
426 (1613)
24 (91)
24 (90)
60 or 90 (4 or 6)
30 or 60 (2 or 4)
250 (120)
149 (65)
Weight
Weight of fire box
Weight of pressure vessel (30 psi) 6
Weight of pressure vessel (60 psi) 6
Weight of displacement rods
Weight of flue gas blower
Weight of in-feed auger
Total weight without water (30 psi) 7
Total weight without water (60 psi) 7
Total weight with water (30 psi) 7
Total weight with water (60 psi) 7
lb. (kg)
lb. (kg)
lb. (kg)
lb. (kg)
lb. (kg)
lb. (kg)
lb. (kg)
lb. (kg)
lb. (kg)
lb. (kg)
1049 (477)
4885 (2216)
4974 (2256)
191 (87)
88 (40)
315 (143)
6532 (2963)
6620 (3003)
7485 (3395)
7573 (3435)
1278 (581)
6535 (2964)
6667 (3024)
310 (141)
88 (40)
315 (143)
8530 (3869)
8662 (3929)
10280 (4663)
10412 (4723)
1410 (641)
7408 (3360)
7452 (3380)
359 (163)
99 (45)
315 (143)
9595 (4352)
9639 (4372)
11585 (5255)
11629 (5275)
1712 (778)
9764 (4429)
9875 (4479)
484 (220)
136 (62)
315 (143)
12416 (5632
12527 (5682)
15340 (6958)
15450 (7008)
2061 (937)
11233 (5095)
11453 (5195)
636 (289)
136 (62)
328 (149)
14401 (6532)
14621 (6632)
17730 (8042)
17950 (8142)
1Minimum load: Operation with modulated control (Infinitely variable power control)
Low load with ON Qmin / OFF (Stop-and-go mode)
2Moist fuels: >W35 further limitations regarding output, degree of efficiency and control behavior
3Specification: See section on Wood Fuel Requirements
4Flue gas temperature: An increase is possible by removing the displacement rods [Full load 86° F (30° C);
Partial load 50° F (10° C)]
5Pressure: Per ASME Sec. IV
6Weight: Includes door and refractory concrete lining
7Overall weight: Includes displacement rods
Other influences: Fuel, water content, ash content, pneumatic cleaning system yes/no; track time
(number of operating hours without cleaning).
Specifications for the start of the track time [toward the end of the track time there
is an increase in the flue gas temperature by approx. 68° F (20° C)]
Mechanical

14
5443 109 v1.9
Pyrot Technical Data
Dimensions
Boiler Model KRT- 150 220 300 400 540
a in. (mm) 157/16 (392) 16 (406) 16 (406) 18e(466) 18e(466)
b in. (mm) 60f(1541) 60 (1525) 7313/16 (1875) 707/8(1800) 7915/16 (2030)
c in. (mm) 141/16 (358) 141/16 (358) 137/8(352) 14c(375) 14c(375)
d in. (mm) 75d(1908) 85e(2168) 86d(2182) 96c(2457) 99b(2527)
e in. (mm) 1115/16 (303) 127/16 (316) 127/16 (316) 129/16 (319) 129/16 (319)
f in. (mm) 43 (1093) 467/16 (1179) 467/16 (1179) 48 (1219) 50e(1279)
g in. (mm) 3 (DN 80) 3 (DN 80) 5 (DN 125) 5 (DN 125) 5 (DN 125)
h in. (mm) 12213/16 (3120) 13413/16 (3424) 14813/16 (3780) 157f(4004) 1665/8(4232)
k in. (mm) 149/16 (370) 149/16 (370) 175/16 (440) 175/16 (440) 249/16 (548)
l in. (mm) 34a(870) 45a(1150) 45a(1150) 54c(1390) 54c(1390)
m in. (mm) 69b(1765) 7911/16 (2024) 7911/16 (2024) 891/16 (2262) 9113/16 (2332)
n in. (mm) 717/8(1825) 821/16 (2084) 821/16 (2084) 95e(2422)*198d(2492)*1
o in. (mm) 279/16 (700) 279/16 (700) 279/16 (700) 279/16 (700) 293/16 (742)
p in. (mm) 34a(870) 45a(1150) 45a(1150) 54c(1390) 54c(1390)
q in. (mm) 26b(673) 26b(673) 26b(673) 26b(673) 29b(750)
r in. (mm) 41e(1050) 52e(1330) 52e(1330) 617/8(1570) 617/8(1570)
Boiler Dimensions
Mechanical
*1For Pyrot 400/540 - Suspension gear is detachable.
BR BS
BR Boiler Return
BS Boiler Supply

15
5443 109 v1.9
Pyrot Technical Data
Boiler Dimensions (continued)
Mechanical
Dimensions
Boiler Model KRT- 150 220 300 400 540
a in. (mm) 119b(3035) 120b(3059) 1347/16 (3415) 136d(3457) 1451/16 (3685)
b in. (mm) 889/16 (2250) 89b(2274) 1039/16 (2630) 10215/16 (2614) 1117/16 (2842)
Legend
ABoiler Return
BBoiler Supply
CAutomatic de-ashing system (optional)

16
5443 109 v1.9
Pyrot Technical Data
Boiler Components
Mechanical
Legend
AFlue gas blower
BBoiler door with rotary blower
CExtinguishing water connection cin.
DIn-feed auger
EGrate motor
FAsh doors of the grate ash container (2 units)
GMotor for automatic de-ashing system
HFire box
IIncline auger for automatic de-ashing system
JLight barrier for in-feed auger
KLimit switch for maintenance cover
LTemperature sensor for in-feed auger
MLight barrier for ember monitoring (2 locations)
NLight barrier for automatic de-ashing system
Legend
APneumatic cleaning system (optional)
BCleaning cover, flue gas collector,
alternate port for the flue gas blower
CCover with sight glass
DRecirculation gas line, line routing variable
EAutomatic ignition unit
EAutomatic ignition
FArticulated head blower
GFlue gas temperature sensor
HOxygen sensor
BS Boiler Supply
BR Boiler Return

17
5443 109 v1.9
Pyrot Technical Data Mechanical
Automatic De-ashing System
Description
De-ashing in Ash Bin, 63.5 USG (240 L)
De-ashing in Ash Bin, 211.3 USG (800 L)
Complete auger de-ashing from the ash chamber for the
fire block into an externally situated movable galvanized
ash bin. A light barrier control system keeps the level of
the ashes constantly over the auger.
As a result, the ash in the ash pan under the incineration
system can burn out, and in normal operation only cool
ash that has burned out is conveyed into the container.
Boiler Model KRT- 150 220 300 400 540
Dimensions
w in (mm) 913/16 (249) 1213/16 (319) 1213/16 (319) 117/8(301) 117/8(301)
x in (mm) 40¼ (1023) 40¼ (1023) 47 (1193) 501/8(1273) 557/16 (1408)
Connection station with moveable ash bin; mountable at 90° and thus making it possible to select the direction in which it moves out.
Standard variations and A-D are also possible in mirror-inverted fashion.
Extension of ascending conveyor auger per meter
Extension of de-ashing auger per meter
Ash bin, 64 USG (240 L), spare
Ash bin, 211 USG (800 L), spare
Supplied with:
- Boiler ash chamber with ash level control system and
de-ashing auger made of high-temperature steel drive
via worm-geared motor
- Connection station with moveable ash bin
- Triggering system for the drives
- Infrared light barrier for level monitoring of ash in the
firebox
Data and dimensions for de-ashing into ashbin, 64 USG (240 L)

18
5443 109 v1.9
Pyrot Technical Data
Mechanical
De-ashing in Base Container
Description
De-ashing in Base Container (for Pyrot KRT-150)
De-ashing in Base Container (for Pyrot KRT-220)
De-ashing in Base Container (for Pyrot KRT-300)
De-ashing in Base Container (for Pyrot KRT-400)
De-ashing in Base Container (for Pyrot KRT-540)
Complete de-ashing by auger of the fire box ash chamber
into the maximum volume base container situated under
the boiler. A light barrier control system keeps the ash
level over the auger even. As a result, the ash in the ash
chamber under the gasification system can burn out,
and in normal operation only cool ash that has burned
out is conveyed into the container. With the large base
container, maximum maintenance-free intervals are
achieved.
Supplied with:
- Boiler ash chamber with ash level control system and
de-ashing auger made of high-temperature steel;
powered by a worm drive motor
- Base container with maximum volume and two
maintenance doors for removing ash by vacuum or rake
- Control of the de-ashing by light barrier
Boiler Model KRT- 150 220 300 400 540
Dimensions
f in (mm) 291/8(740) 291/8(740) 345/8(880) 3713/16 (960) 431/8(1096)
g in (mm) 1711/16 (450) 203/16 (513) 31 (787) 1715/16 (456) 2111/16 (551)
i in (mm) 233/8(593) 26¾ (680) 26¾ (680) 31½ (800) 31½ (800)
Volume of base container
USG (L) 63 (240) 95 (360) 100 (380) 158.5 (600) 185 (700)
Weight of complete de-ashing system (in addition to boiler weight)
lb (kg) 705 (320) 749 (340) 793 (360) 838 (380) 882 (400)
Data and dimensions for de-ashing in base container

19
5443 109 v1.9
Pyrot Technical Data Mechanical
Pneumatic Cleaning System
Description
Pneumatic Cleaning System (for Pyrot KRT-150)
Pneumatic Cleaning System (for Pyrot KRT-220)
Pneumatic Cleaning System (for Pyrot KRT-300)
Pneumatic Cleaning System (for Pyrot KRT-400)
Pneumatic Cleaning System (for Pyrot KRT-540)
The complete heat exchanger is cleaned off by periodic
blasts of compressed air while the system is in regular
operation. During the cleaning process the individual
sections are blasted clean one after another.
The ash on the heat exchanger tubes is detached by very
short but strong blasts of air. The particles detached are
conducted by the flow of gas to the de-duster, where
most are filtered out and collected. The system is built
into the rear side of the boiler. The compressor should
preferably be installed in a cool spot in the heating room.
Boiler Model KRT- 150 220 300 400 540
Number of zones/valves 4 4 4 5 6
Size of the valves G 1” G 1” G 1” G 1” G 1”
Max. air consumption at full load USG/h (L/h) 343 (1300) 660 (2500) 660 (2500) 872 (3300) 1189 (4500)
A customer supplied air compressor has to deliver at
least the quantity and quality of air specified and have
an adjustable pressure controller as well as a safeguard
against hose rupture (e.g. operating time limiter).
Function of the control system:
The number of cleaning cycles within one time unit (e.g.
per hour) is adapted to the load of the boiler.
One individual, complete cleaning cycle consists of a
series of pressure impulses over all the sections of the
heat exchanger.
Supplied with:
- Nozzle element integrated in the exhaust gas collector,
incl. connection piece with heat dissipation plates
- Compressed air distributor with container and valve;
with high-temperature hoses connected to the nozzle
element
- Compressor (optional) with the following specs:
Delivery capacity of 11.3 CFM (0.32 m3/min); tank:
60 USG (227 L); pressure: max. 135 psi; motor: 3 HP,
1200 RPM, 230V, includes pressure controller,
pressure switch and operating time limiter; plug and
play; noise level of normal design: 75 dBA
- Compressed air hose to max. of 13 ft (4.0 m) in length
and ¾” in diameter
- Valves permanently wired on terminal strip
- Software component in the control system
To be carried out by the customer:
- Provide a power supply, 120V or 230/1/ 16A
Technical data

20
5443 109 v1.9
Pyrot Technical Data
Dimensions
Boiler Model KRT- 150 220 300 400 540
a in. (mm) 11b(292) 11b(292) 1211/16 (323) 1211/16 (323) 17e(442)
b in. (mm) 97/8(250) 97/8(250) 117/8(300) 137/8(350) 137/8(350)
c in. (mm) 9d(232) 10d(257) 107/8(277) 14 (355) 14 (355)
d in. (mm) 141/16 (358) 141/16 (358) 137/16 (352) 14c(375) 14c(375)
e in. (mm) 97/8250 97/8(250) 11c(300) 13c(350) 13c(350)
f in. (mm) 47/8(125) 47/8(125) 57/8(150) 67/8(175) 67/8(175)
It is recommended to install a draft damper in the chimney 1.
The draft damper is field supplied.
Optional, the Viessmann supplied draft damper can be
installed in the flue gas pipe of the biomass boiler 2.
The draft damper should be installed in the flue gas pipe
(not included) as close as possible to the chimney not
closer than 39eIn. (1000 mm) to the outlet of the flue
gas blower. The final position has to be arranged with the
chimney supplier. The draft damper must be installed in
the heating room together with the biomass boiler.
Chimney Connection
Mechanical
recirculated flue gas draft damper