5
Hoval STU Wood Pellet Boiler
Boiler Delivery, Offloading and Storage
Boilers and associated equipment are normally delivered by our own transport on a mutually agreed date. The boiler can be off-loaded
by the crane lorry if specifically booked at the time of ordering. Adequate lifting points are provided on the boiler shell.
The STU Wood Pellet Boiler would normally be delivered fully cased with the boiler temperature gauge attached. The stoker, the fuel
delivery system and the associated control panel would normally be delivered and supplied with the boiler. The stoker control panel can
either be mounted on the side of the boiler (standard) or supplied separately for mounting on a wall within the boiler house.
Where specified any pellet store may be supplied separate to that of the boiler.
On delivery the installer should check all items against the delivery note and should then store them in a safe secure dry place.
(There may be small items such as cleaning tools and safety valves, which are transported in the boiler combustion chamber. These
should be removed and also stored in a safe place).
Note:
Hoval approved engineers will assemble the stoker and the fuel feed system but would normally expect the installer to wire between
the various motors and dampers on the stoker and the control panel unless it is mounted on the boiler or unless the wiring instruction is
given at the time of order. Detailed instruction as to how to complete this wiring is available separately.
Description and Technical Performance of the STU Wood Pellet Boiler
Applications
These boilers are intended for heating commercial and industrial premises within the limits of temperature and pressure stated within this
manual. They may also be used to supply DHW to such premises in conjunction with an indirect calorifier.
General Details
Based on Hoval's well-established ST design the STU Wood Pellet boiler is a welded steel boiler complete with a matched pellet stoker,
designed to operate with wood pellet fuel. As standard the stoker is supplied for manual lighting of the fuel bed. An optional ignition start
system is available on request, but this must be specified at the time of order.
The boiler comprises of a welded steel shell with a water jacket surrounding an oval combustion chamber and a single bank of smoke
tubes.
STU Wood Pellet boilers are offered in outputs from 150 to 1000kW for heating only, the standard version available for operating working
pressures of up to 3 bar and temperatures of 90
o
C.
Manufactured in the UK under ISO 9001:2000 Quality Management System.
The STU has been designed with generous water content and good natural circulation is achieved through the boiler with wide unrestricted
waterways and optimum location of the flow and return connections.
Boiler flow connection is located off the top of the boiler. Two return connections are located either side at the rear of the boiler.
Return water flow should be divided equally across both returns to promote good water circulation.
A safety valve needs to be fitted on the boiler.
Boiler Door Hinging can be either side (standard is right hand side).
Insulated with high-density mineral fibre mats with woven fabric surface reinforced as boiler cladding insulation.
Meets BS EN303-5 Class 3 requirements with respect to Safety, Boiler Efficiency and Emissions.
Each STU boiler is fitted with thermostatically controlled Thermal Safety overheat coils.
Boiler Control includes flow temperature control along with limit stats. In addition each STU is supplied with a Control Panel incorporating
the following switches ON/OFF isolator, AUTO/IGNITION (where optional ignition system is specified), ID Fan AUTO/ID FAN ONLY,
Wood Burner KINDLE/OFF/AUTO that control the stoker along with a LRP controller and display. Normal operation is fully automatic in
conjunction with a simple time switch or some other form of control, i.e. BMS enable signal. On STU Models 500 to 1000, invertor drive
units are supplied as standard for control of the conveyor auger, FD fan and ID fan motors. On request these are available as an option
on Models 150 to 425, which must be specified at the time of order.
Electrical power supply; A three phase 400V, 32A isolated supply is to be provided by the installer to the Stoker Control Panel. Specific
wiring diagrams will be issued on commissioning.
