Pyro Fires are renowned for burning very cleanly when dry fuel is used but you should still always clean your flue once a year. This is often a requirement for many insurance companies.
Keeping your flue pipes clean will help eliminate the risk of a flue fire. Your flue is also a great indication of how your wood fuel is performing. If the pipes are clean then the wood is good, if the pipes are filling up with carbon, creosote and tar deposits then you may need to revisit the operating instructions and refresh yourself with how to create a cleaner burning fire.
The easiest way to clean the flue is by placing a deep baking tray or similar under the base of the flue and sweep the flue down into this, this stops all the debris from falling into the top chamber and requiring vacuuming out. Sweeping the flue into the top chamber is never a good idea as it can restrict the flow of gasses from the primary fire chamber and cause your fire to perform poorly.
To clean the top chamber and wetback, you will need to remove the top plate (it just lifts off) and clean out the top chamber of soot and creosote. Take care not to remove any of the Kaowool lining during cleaning and ensure that the gasket is all intact before replacing the top plate. Support the flue with a frame made of wood so you can easily remove the top plate.
The build-up around the wetback is best removed by hand. The wetback can be knocked out of alignment if it is moved when the creosote is being cleaned off so be careful as this can cause the constant rise to be knocked out of alignment and can result in water hammer developing in the system.