STU (200-975)

The STU is a modulating high efficiency skid mounted commercial wood pellet boiler fitted with external stoker and fuel pick-up system. The STU ranges from 200kW to 975kW. A flexi-worm feed screw is available to connect to storage facilities as an alternative if required.


The above directive is intended to help improve air quality by limiting emissions from all boilers and generators sized at 1 MW or 1000 kW or above. (1)

Eventually all boilers and generators will be covered by this directive but IMPORTANTLY any plant that is installed and commissioned after 20th December 2018 will have to comply with emission limit values that have been set and defined for NEW plant or equipment. Boilers installed and commissioned prior to this date will be classed as Existing plant or equipment and will be subject to less rigorous emission limit values and will not require permitting immediately.

The Hoval STU 975 and STU 1000 will be affected by this directive and as a consequence to ensure compliance both will need to be installed with a twin ceramic filter arrangement if commissioned after the date indicated (instead of the current twin cyclone unit). 

In addition operators will be required to demonstrate that the boilers meet the emission limit values for both NOx and Dust or Particulate Matter (PM) which will require periodic site based testing. Any site tests will require sufficient load or duty for the boilers to operate continuously at or close to their maximum output for several hours. Clients should ensure that prior to installation sufficient duty will be available to complete these tests.

(1 Based on heat input, net calorific value basis.
Low emissions due to burning renewable wood fuel
You can claim the Renewable Heat Incentive
Versatile operation
Simple maintenance