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Can you install a Woodburner on a short flue?
Building Regulations recommend a minimum flue height of 4.5m however the chimney must be high enough to allow for enough draught to clear the exhaust gases. The Height will depend on the type of appliance, height of the building and the number of offsets in the system.
You should always check what the manufacturers manual states for flue requirements.
Let’s look at an example from Stovax on a Stockton stove
As you can see 4.5 metres minimum flue height is a standard requirement for a stove.
A Flue Draught reading can be carried out on commission of the stove
Hetas says,
"Flue Draught Test
The constant flow of flue gases at the correct rate of flow with the least possible variation is required for safe and efficient combustion. Insufficient flue draught will cause ignition difficulties and is likely to result in fume emission and a potential health risk. Too much draught will make control of the fire difficult and may result in overheating. In this instance, fitting a draught stabiliser may be required. An appliance manufacturer will specify a range of flue draft conditions under which their appliance will operate.
Flue draught readings can be taken using a purpose made flue draught gauge or using any suitable pressure differential measurement device.”
(Hetas - https://www.hetas.co.uk/feeling-the-draught/)
There are also other regulations to consider when it comes to chimney height. Such as Flue Termination regulations (where the flue and chimney cap ends)
Read more on Termination position for solid fuel application here.
Installing a twin wall flue in a conservatory or Bungalow
It can be tricky when installing a twin wall flue in a conservatory or Bungalow as you may have 2-3 metres of flue above the roof. This can be off putting with a prospect of installing ugly roof stays.
Poujoulat offer the perfect solution for this situation with its reinforced locking bands and a rafter support. Poujoulat therminox has been tested to go three metres unsupported.
For further support and the most cosmetically pleasing termination lengths Poujoulat offers an STI Flashing and STI Chimney. This gives a sturdy and rigid base which is ideal for situations where there is a taller flue outside.
Is it possible to have a short flue in any situations?
When fitting a Woodburner in a summer house, cabin, boat or garden shed the regulations are different. Some manufacturers have tested their stoves on a purpose-built kit for these situations for example.
The Morso Squirrel which has a 5” collar and in a house, situation would require 4.5 metres of 5” flue. In a cabin or boat can be installed using Morso Boat kit or Cabin which. These are 4” twin wall flue pipe which are roughly 2-3 metres long.
Unless the stove you are buying has been tested to operate on a short flue or tested to operate on a flue kit like Morso’s. It will always be a risk that the stove will not perform correctly and may not meet regulations (depending on the situation). It is always wise to prepare for the possibility of having to have a longer flue if you are trying to install using a short flue.
Always speak to a hetas installer first to ensure safety and refer to the manufacturer’s guidelines.