Do EcoDesign regulations affect the FHT Stove?
Many people will be aware that the new EcoDesign regulations for stoves came into force in January 2022.
These regulations enforce strict requirements for improved efficiency and reduced emissions from stoves.
This has caused most stove manufacturers to stop making ‘back boiler’ stoves after December
2021 as the ‘jacket’ which forms the boiler replaces firebricks and surrounds the fire, so
cooling the combustion zone, resulting in high emissions which cannot meet the regulations.
Unlike the back boiler, the FHT Stove does not surround the combustion chamber, so the high temperature
combustion conditions required to reduce emissions can be maintained. The FHT Stove is one of the few
technologies which can connect a wood burning stove to a central heating circuit going forward. Of course
there are all the other advantages of the FHT Stove over the traditional technology as well!
Can the FHT Stove be connected to a ‘Combi’ central heating system?
Yes!   FHT Stove components are designed for operation with pressurised central heating
systems as required for ‘Combi’ boilers. Stove heat can circulate in the heating system to
supply radiators but cannot heat the hot water as this requires the short-term high output
of the boiler for ‘instant’ heating.
How many radiators can an FHT Stove supply?
Around half of the stove output can be sent to the central heating system.
For a nominal 5kW stove (range 3~7kW) typically 2~3kW of heat is transferred
to the heating system when the fan is ‘on’. This is not enough to heat the
whole house, but would provide all the heat for a moderate sized adjacent room.
When used with a central heating system, the heat gets dispersed throughout
the house, so this either gently warms the rooms away from the stove, or reduces
the amount of fuel used by the central heating boiler when operated in parallel.
In terms of radiator sizing, one typical radiator, 600mm tall, 1200mm wide, single
panel, will output around 1,200W at 75°C water temperature, so 2~3 radiators can be supplied.
Is the FHT Stove noisy?
The FHT Stove incorporates a small electric fan to direct air heated by the stove surfaces
towards a heat exchanger. The fan is optimised to be quieter than most refrigerators
and consumes only around 10W of power - about the same as an energy efficient light bulb.
Are there any restrictions to the location of radiators connected to the FHT Stove?
No! The FHT Stove utilises a low power pumped circuit where hot water can be sent to radiators
in any location, even on floors below the room in which the stove is located. There is no need for
wide bore pipes for ‘natural circulation’ as required for most ‘back boiler’ stoves.
When the FHT Stove is connected to an existing central heating system, stove heat is distributed
throughout the home via the heating system, supplying any radiator that is turned on and working
in parallel with the central heating boiler if it is operating.
Do I need big pipes to connect the FHT Stove?
No!   The FHT Stove can be connected in any preferred pipe bore provided sufficient flow
can be achieved. Connection via small bore piping allows neat, hidden pipe-work to be used
so that the appearance of your installation is not affected.
Can the FHT Stove be connected to pressurised central heating systems?
Yes!   FHT Stove components are designed for operation in excess of 3Bar in line with
requirements for pressurised heating systems (with an expansion vessel). The FHT Stove can also
be connected to open vented systems if required. See also 'Combi' answer above.
What happens in the event of a power supply failure?
The FHT Stove simply reverts to ‘off’ mode and all the stove heat is released into the room
in which the stove is located. The design is fail-safe and cannot result in the central heating
water boiling in the stove.
Can I have TRVs on my radiators?
Yes! This is a unique feature of the FHT Stove. Whether the stove is sending heat to the
central heating system or a dedicated radiator loop, the radiators can be turned ‘on’
and ‘off’, or can be controlled by thermostatic valves. The FHT Stove incorporates simple
controls that detect whether there is sufficient heat demand elsewhere to distribute heat,
and if necessary it can turn off if the water becomes too hot.
What happens if the radiators are turned off?
See answer above - if there is not a heat demand the FHT Stove simply reverts to sending
all the heat to the room as hot air.
How does the FHT Stove compare to back boiler systems with safety quench circuits?
A number of stove manufacturers were offering back boiler systems which incorporate a
safety feature which feeds cold water through the back boiler to prevent boiling if the water
overheats. Whereas such technology is clearly an important safety advance over a simple back
boiler system, it only offers emergency protection to the customer. The FHT Stove offers fail-safe
operation which does not rely on additional cold water ‘quench’ circuits (and the plumbing
costs associated), but also offers the considerable benefit of giving the user the ability
to choose whether to transfer heat or to send all the heat to the room.
Following the introduction of EcoDesign regulations in January 2022, it is unlikely that any
manufacturer will be offering the traditional ‘back boiler’ as
explained above. They may be able to offer smaller output connections based on heat exchange with
exhaust gasses above the combustion zone (flue boilers) but the same safety issues will apply
and the other advantages of the FHT Stove will not be available.
Is the FHT Stove a replacement for back boilers?
No - although it does offer considerably lower installed costs for customers who specifically
want a 'back boiler' system. Typically, ‘back boiler’ stoves transfer a higher proportion of
the fire heat to a radiator circuit whenever the stove is lit with no on/off control.
The FHT Stove is aimed at all stove users, primarily to give additional comfort control, improved
efficiency, and a reduced Carbon ‘footprint’. As the FHT Stove can be turned ‘on’
and ‘off’, customers
can choose to have all the heat passing to the room, or if it becomes too warm, to direct around half
of the heat to other locations via the existing central heating system or a dedicated radiator loop.
Can FHT Stoves be used in Smoke Controlled Regions?
Yes! All stoves produced from January 2022 now meet the DEFRA exemption to operate
in smoke controlled regions as they have to meet EcoDesign regulations. Prior to the
EcoDesign Regulations, manufacturers had to make additional tests over and beyond the
EN13240 test requirements to prove that their products met the stricter requirements for
DEFRA exemption. See also answer to
Do EcoDesign regulations affect the FHT Stove?
Not answered your question?
Please email FHT Stoves (firstname.lastname@example.org
) with any further questions or comments.